306 C HA P T E R 1 0 Clinical Technique for Amalgam Retoration

10
Clinical Technique for Amalgam
Restorations
LEE W. BOUSHELL, ALDRIDGE D. WILDER, JR., SUMITHA N. AHMED

D
ental amalgam (silver amalgam or simply amalgam) is a amalgam may result in unnecessary weakening of teeth because
metallic, polycrystalline restorative material originally of the demand for additional removal of tooth structure so as to
composed of a mixture of silver–tin alloy and mercury. accommodate amalgam’s strength and retention requirements.
Current alloys that are amalgamated with mercury are silver–tin– While it is true that preparations for composite resin restorations
copper. he unset silver-colored mixture is pressed (condensed) may allow smaller, more conservative preparations for very early
into a tooth defect (cavitation) that has been speciically prepared caries lesions, treatment of more advanced lesions may result in
to retain the amalgam. he material is then contoured to restore essentially the same amount of tooth structure loss regardless of
the tooth’s form so that, when the material hardens, the tooth is the type of restorative material being used. he choice of a composite
returned to normal function (Fig. 10.1). Amalgam has been the resin material over amalgam may be based on the assumption that
primary direct restorative material in the United States for more both materials will perform equally well over time for all patients.
than 150 years. It has been the subject of intense research and has However, a growing body of evidence suggests that the risk of
been found to be safe and beneicial as a direct restorative material developing secondary caries adjacent to amalgam restorations is
(see Chapter 13).1-3 he cost-efective nature of amalgam restorations at least two times less likely than that of composite resin restorations
has beneited many people. According to the U.S. Public Health in high caries risk patients, and therefore the reduction/phase-out
Service, “hundreds of millions of teeth have been retained that of dental amalgam may have been premature.10,11 he decline of
otherwise would have been sacriiced because restorative alternatives amalgam use is also due to perceived concerns over individual and
would have been too expensive for many people.”4 environmental safety relative to the presence of elemental mercury
In addition to being cost efective, amalgam has the unique in amalgam restorations. Safe, professional handling of mercury
property of being “self-sealing.” Self-sealing occurs when percolation in mixing the amalgam mass, removal of old amalgam restorations,
of oral luids (i.e., microleakage) between the amalgam restoration and amalgam scrap disposal is certainly appropriate and absolutely
and the prepared cavity walls results in corrosion of the amalgam essential. Following best management practices for amalgam waste,
and a subsequent accumulation of corrosion products in the as presented by the American Dental Association, results in
microscopic space. Microleakage between the restoration and appropriate amalgam use.12
the adjacent tooth structure is reduced as corrosion products ill
the space. he self-sealing process is self-limiting and requires several
months. Amalgam is the only restorative material with an interfacial Type of Amalgam Retorative Material
seal that improves over time.5-7 Low-Copper Amalgam
Amalgam was introduced to the United States in the 1830s.
Initially, amalgam restorations were made by dentists iling silver Low-copper amalgams were primarily used before the early 1960s.
coins and mixing the ilings with mercury, creating a puttylike When the setting reaction occurred, the material was subject to
mass that was placed into the defective tooth. As knowledge corrosion because of the formation of a tin–mercury phase
increased and research intensiied, major advancements in the (gamma-2). he corrosion led to the rapid breakdown of amalgam
formulation and use of amalgam occurred. Concerns about mercury restorations. Subsequent research led to the development of high-
toxicity in the use of amalgam were, however, expressed in many copper amalgam materials. Currently low-copper amalgams are
countries; concerns reached major proportions in the early 1990s. rarely used in the United States.
Today, the popularity of amalgam as a direct restorative material
has decreased.8,9 he decline is attributed in part to increased
High-Copper Amalgam
interest in tooth-colored composite resin restorations and the
minimally invasive nature of their preparation steps. Concerns High-copper amalgams are predominantly used today in the United
have been raised that the preparation used when planning for States. In this book, unless otherwise speciied, the term amalgam

306
 CHAPTER 10 Clinical Technique for Amalgam Retoration 307

amalgam restorative materials. Alloys with gallium or indium or

alloys using cold-welding techniques have been presented as
alternatives to mercury-containing amalgams. None of these new
alloys have shown suicient promise to become a universal replace-
ment for current amalgam materials.18-21

Important Amalgam Propertie

he linear coeicient of the thermal expansion of amalgam is 2.5
times greater than that of tooth structure, but it is closer to that of
tooth structure than the linear coeicient of thermal expansion of
composite.22-24 Although the compressive strength of high-copper
amalgam is similar to tooth structure, the tensile strength is lower,
making amalgam restorations prone to fracture during lexure.9,25,26
Usually, high-copper amalgam fracture is a bulk fracture, not a
marginal fracture. All amalgams are brittle and have low edge strength.
As such, the amalgam restoration must have suicient bulk (usually
1.5–2 mm in any occlusally loaded area, depending on the position
within the tooth) and a 90-degree marginal coniguration.
Creep and low relate to the deformation of a material under
load over time. High-copper amalgams exhibit no clinically relevant
• Fig. 10.1 Clinical example of an amalgam restoration. (From Hatrick creep or low.27,28 Because amalgam is metallic in structure, it also
CD, Eakle WS, Bird WF: Dental materials: Clinical applications for dental is a good thermal conductor. At minimum, a dentin desensitizer
assistants and dental hygienists, ed 2, St. Louis, Saunders, 2011.) should be used immediately prior to amalgam placement to limit
sensitivity secondary to rapid luid movement in the dentinal tubules
caused by thermal changes. A liner or base should be placed in
refers to high-copper dental amalgam. he increase in copper areas of deep caries removal prior to amalgam placement to limit
content to 12% or greater designates an amalgam as a high-copper thermal sensitivity.
type. he advantage of the added copper is that it preferentially
reacts with the tin and reduces the formation of the more corrosive
phase (gamma-2) within the amalgam mass. This change in General Conideration for Amalgam
composition reduces the deleterious corrosion efects on the restora-
tion. However, enough corrosion occurs at the amalgam–tooth Retoration
interface to result in the sealing of the restoration, which reduces Retoration With Amalgam
microleakage.13,14 hese materials may provide satisfactory clinical
performance for more than 12 years.15,16 High-copper amalgams Amalgam is efective as a direct restorative material because of its
are available with admixed or spherical alloy structure. easy insertion into a tooth preparation and, when hardened, its
ability to restore the tooth to proper form and function. he tooth
preparation not only must remove the fault in the tooth and
Admixed Amalgam remove weakened tooth structure, but its form must also allow
Admixed amalgam contains irregularly shaped and sized alloy the amalgam material to function properly. he required tooth
particles, sometimes combined with spherical shapes, which are preparation form must allow the amalgam to (1) possess a uniform
mixed to form a mass that is placed into the tooth preparation. speciied minimum thickness for strength (so that it will not lex
he irregular shape of many of the particles results in a mass that and fracture under load), (2) produce a 90-degree amalgam angle
requires greater condensation pressure (which many dentists prefer) (butt-joint form for maximum edge thickness) at the margin, and
and permits the dentist to displace matrix bands to generate proximal (3) be mechanically retained in the tooth (Fig. 10.2A and B).
contacts more easily. Amalgam restorations initially leak and therefore require steps to
protect from pulpal sensitivity until self-sealing is able to occur
(Fig. 10.3A).13 After desensitizing the prepared tooth structure,
Spherical Amalgam mixing, inserting, carving, and inishing the amalgam are relatively
A spherical amalgam contains small, round alloy particles that are fast and easy. he placing and contouring of amalgam restorations
mixed with mercury to form the mass that is placed into the tooth are generally easier than those for composite restorations.29 For
preparation. Because of the shape of the particles, the material is these reasons, it is considered a user-friendly material that is less
condensed into the tooth preparation with little condensation technique (i.e., operator) sensitive as compared with composite.
pressure. his advantage is combined with its high early strength Some practitioners have continued to use bonded amalgam
to provide a material that is well suited for very large amalgam restorations in their practice (see Fig. 10.3B). As noted in Chapter
restorations such as complex amalgams or foundations.17 4, this book does not promote the use of bonded amalgams.30-33
he bonding of amalgam requires use of a dual-cure adhesive system
to form a hybrid layer with the dentin followed by condensation
New Amalgam Alloy of amalgam so that amalgam particles become intermingled with
Because of the concern about mercury toxicity, new compositions the curing adhesive resin. A bonded amalgam restoration, done
of amalgam have been promoted as mercury-free or low-mercury properly, may seal the prepared tooth structure and may temporarily
308 C HA P T E R 1 0 Clinical Technique for Amalgam Retoration

Amalgam

90-degree
cavosurface Desensitizer
margins DEJ

Pulpal floor

A Intertubular
dentin

Dual cured
adhesive Amalgam intermingled
with adhesive

B Axial wall Amalgam

• Fig. 10.2 A and B, Diagrams of Class II amalgam tooth preparations
illustrating uniform pulpal and axial wall depths, 90-degree cavosurface
margins, and occlusal convergence of walls.

Hybrid
layer

strengthen adjacent tooth structure. he strengthening and retention

gained by bonding, however, is minimal and short term. Consequently,
bonded amalgam restorations still require the same tooth preparation
retention and resistance form as do nonbonded amalgam
restorations.34-35 Isolation requirements for a bonded amalgam
restoration are the same as for a composite restoration.
Another amalgam technique uses light-cured adhesive to seal
the dentin under the amalgam material (see Fig. 10.3C). his
procedure, as is true of all procedures that use adhesive technology, B Dentin tubule
requires proper isolation. he prepared tooth structure is etched
(i.e., demineralized), primed, and sealed with adhesive. he adhesive
is polymerized before insertion of the amalgam. his technique
seals the dentinal tubules efectively.36,37 Amalgam

Ue of Amalgam Light-cured

adhesive
Amalgam is used for the restoration of many carious or fractured
posterior teeth and in the replacement of failed restorations. Hybrid
Understanding the physical properties of amalgam and the principles layer
of tooth preparation is necessary to produce amalgam restorations
that provide optimal service. When properly placed, an amalgam
restoration is able to provide many years of service.38-43 Although
improved techniques and materials are available, amalgam failures
do occur. Much clinical time is spent replacing restorations that
fail as a result of recurrent caries lesions, marginal deterioration
(i.e., ditching), fractures, or poor contours.44,45 Attention to detail
throughout the procedure may signiicantly decrease the incidence Peritubular
of failures, however, and extend the life of the restoration.46-48 C dentin
Careful evaluation of existing amalgam restorations is important • Fig. 10.3 Methods to limit initial pulpal sensitivity after amalgam place-
because they have the potential to provide long-term clinical service ment. A, Dentin desensitization. B, Amalgam bonding (amalgam inter-
and should not be removed and replaced unless accurately identiied mingled with adhesive resin). C, Dentin sealing (adhesive resin placed and
to be defective or undermined by a secondary caries lesion.49 cured before amalgam placement).
 CHAPTER 10 Clinical Technique for Amalgam Retoration 309

A B C

D E
• Fig. 10.4 Amalgam restorations. A–C, Class I. D, Complex. E, Class V. (Most practitioners would
restore all of these teeth with composite, except tooth No. 30.)

Because of its strength and ease of use, amalgam provides an may be more appropriate than composite resin when there is little
excellent means for restoring large defects in nonesthetic areas.50 to no natural occlusal tooth structure remaining that requires the
A review of almost 3500 four-surface and ive-surface amalgams restoration to restore most or all of the occlusal contacts.53
revealed successful outcomes at 5 years for 72% of the four-surface
and 65% of the ive-surface amalgams. When considering complex Iolation Factor
amalgam restorations and discussing treatment options with patients,
this result should be compared with the 5-year success rates for Isolation of the operating ield is important for moisture control,
gold and porcelain crowns, which were 84% and 85%, access, and visibility, to protect the patient from aspirating or
respectively.51 ingesting foreign objects, protecting the pulp in the event of pulpal
exposure, and protecting the operator medicolegally. However,
minor moisture contamination of amalgam during the insertion
Indication procedure may not have as adverse an efect on the inal restoration
Amalgam may be used for Class I, II, V, and VI restorations; for as the same contamination would for a composite restoration.
foundations; and for caries-control restorations (Figs. 10.4 and
10.5; see also Chapter 2). Occasionally amalgam may be utilized Operator Ability and Commitment Factor
for Class III areas if isolation problems exist. Likewise, Class V
amalgam restorations may be indicated in anterior areas where he tooth preparation for an amalgam restoration is very exacting.
esthetics is not an important consideration and the patient has It requires a speciic design with depths that allow appropriate
high caries risk. amalgam thickness and a precise marginal form. he failure of
amalgam restorations is often related to inappropriate tooth
preparation. However, the insertion and inishing procedures for
Contraindication amalgam are much easier than for composite.29
Amalgams are contraindicated in patients who are allergic to alloy
components. he use of amalgam in more prominent esthetic areas Advantage
of the mouth may represent a relative contraindication. hese areas
include anterior teeth and, in some patients, premolars and molars. Some of the advantages of amalgam restorations already have been
Amalgam should not be used when composite resin would ofer stated, but the following list presents the primary reasons for the
more conservation of tooth structure and equal clinical performance. successful use of amalgam restorations over many years.
1. Ease of use
2. High compressive strength
Occlual Factor 3. Excellent wear resistance
Amalgam generally has greater wear resistance than does composite 4. Favorable long-term clinical research results
in patients that have heavy occlusal function.2,52,53 Amalgam also 5. Lower cost than for composite restorations
310 C HA P T E R 1 0 Clinical Technique for Amalgam Retoration

Caries

Slot Pin
Fractured cusp

Slot Pin

A B1 B2

Preparation
margin

Amalgam
foundation

Crown
preparation

Preparation
margin
Pin Pin
C D

• Fig. 10.5 Amalgam foundation. A, Defective restoration (defective amalgam, mesiolingual fractured
cusp, distofaciocclusal caries). B, Tooth preparation with secondary retention, using slot (B1) and pin (B2).
C, Amalgam foundation placed. D, Tooth with amalgam foundation prepared for crown. Note that dashed
lines on the occlusal surface in B1 and B2 only indicate the position of the retention grooves on the facial
and lingual walls of the proximal preparation. The grooves do not extend onto the occlusal surface.

Diadvantage he following sections begin with the introduction of general

clinical techniques and associated concepts to be considered when
he primary disadvantages of amalgam restorations relate to esthetics restoring caries lesions or defects with dental amalgam. he general
and increased tooth structure removal during tooth preparation. technique is then followed by speciic discussion addressing the
he following is a list of these and other disadvantages of amalgam creation of Class I, II, III, V, VI, and Complex Amalgam restorations.
restorations.
1. Noninsulating
2. Nonesthetic General Clinical Technique for
3. Less conservative tooth preparation than for composite restora-
tions (more removal of tooth structure during tooth Amalgam Retoration
preparation)
4. More difficult tooth preparation than for composite
Initial Clinical Procedure
restorations Complete examination, diagnosis, and treatment planning must
5. Initial marginal leakage be completed before a patient is scheduled for operative
 CHAPTER 10 Clinical Technique for Amalgam Retoration 311

appointments (except in emergencies). A brief review of patient’s

dental record (including medical factors), treatment plan, and
radiographs should precede each restorative procedure. At the
beginning of each appointment, the dentist should also carefully
examine the operating site to conirm the diagnosis of the tooth
or teeth scheduled for treatment.

Local Anetheia
Local anesthesia is recommended for most operative procedures.
Profound anesthesia contributes to comfortable and uninterrupted
A
operation and usually results in a marked reduction in
salivation.

Iolation of the Operating Site

Complete instructions for the control of moisture are given in
Online Chapter 15. Isolation for amalgam restorations may be
accomplished with a rubber dam, cotton rolls, with or without a
retraction cord.

Other Preoperative Conideration

B
Preoperative assessment of the occlusion should be made. his
step should occur before rubber dam placement. he dentist should
identify not only the occlusal contacts of the tooth to be restored
but also the contacts on the opposing and adjacent teeth. Knowing
the preoperative location of occlusal contacts is important in
planning the restoration outline form and in establishing the proper
occlusal contacts on the restoration. Remembering the location
of the contacts on adjacent teeth provides guidance in determining
when the restoration contacts have been correctly positioned and
adjusted.
A wedge placed preoperatively in the gingival embrasure is
useful when restoring a proximal surface. his step causes slight
separation of the operated tooth from the adjacent tooth and may C
help protect the adjacent proximal surface, the rubber dam, and
the interdental papilla. • Fig. 10.6 Preoperative visualization of tooth preparation extensions
It is important to preoperatively visualize the anticipated exten- when a cavitated caries lesion is present gingival to the proximal contact
sion of the tooth preparation. Because the tooth preparation requires and in the central groove area. A, Rotated tooth (lingual extension owing
speciic depths, extensions, and marginal forms, the connection to faulty central groove). B, Open proximal contact (preparation extended
of the various parts of the tooth preparation should result in minimal wider faciolingually to develop a proximal contact with appropriate physi-
ologic proximal contours). C, Normal relationship.
tooth structure removal (i.e., as little as is necessary), while maintain-
ing the strength of the cuspal and marginal ridge areas of the tooth
as much as possible (Fig. 10.6). he projected facial and lingual
extensions of a proximal box should be visualized before preparing as possible. Tooth preparation that conserves tooth structure is
the occlusal outline form through the marginal ridge of the tooth, strongly recommended because it limits pulpal irritation and
reducing the chance of overextension while maintaining a butt-joint preserves the integrity of both the tooth and the subsequent
form of the facial or lingual proximal margins. restoration.54-60
Discussion in this chapter will include principles, techniques,
and procedures using classic examples of amalgam preparations.
General Concept Guiding Preparation for However, clinically, the outline form of the preparation should
Amalgam Retoration always conform to the level of disease in the tooth and not necessarily
to the examples presented here. Making the tooth preparation form
A solid comprehension of concepts presented in Chapter 4 is appropriate for the use of amalgam as the restorative material is
essential prior to the learning of information presented in the equally important. he physical properties of amalgam require that
following sections. For an amalgam restoration to be successful, it be placed into a tooth preparation that provides for an approximately
numerous steps must be accomplished correctly. After an accurate 90-degree or slightly greater occlusal cavosurface margin and 90-degree
diagnosis is made, the dentist must create a tooth preparation that axial cavosurface margin (because of the amalgam’s limited edge
not only removes the defect (e.g., caries lesion, old restorative strength). he preparation must allow a minimum thickness of 1.5
material, malformed structure) but also leaves remaining tooth to 2 mm so that the amalgam will not lex and fracture when under
structure as strong as possible by leaving as much dentin support occlusal load (most amalgams fail by bulk fracture). he amalgam
312 C HA P T E R 1 0 Clinical Technique for Amalgam Retoration

1.5 mm

3 mm

0.8 mm
A B C
• Fig. 10.7 Pulpal loor depth. A, Pulpal depth measured from central groove. B, No. 245 bur dimen-
sions. C, Guides to proper pulpal loor depth: (1) one half the length of the No. 245 bur, (2) 1.5 mm, or
(3) 0.2 mm inside (internal to) the dentinoenamel junction (DEJ).

must be placed into a prepared undercut form in the tooth so as to Retention

be mechanically retained (amalgam does not bond to tooth structure). groove
After appropriate tooth preparation, the success of the inal restoration
depends on proper insertion, carving, and inishing of the amalgam
material. DEJ
Axial Pulpal
wall floor
Principle
he basic principles of tooth preparation must be followed for
amalgam tooth preparations to ensure clinical success. As presented
in Chapter 4, the preparation for amalgam is discussed in two A B
stages, for academic purposes, to facilitate student understanding • Fig. 10.8 Axial wall depth. A, If no retention grooves needed, axial
of proper extension, form, and caries lesion removal. he initial depth 0.2 mm inside (internal to) the dentinoenamel junction (DEJ). B, If
stage (1) places the tooth preparation extension into sound tooth retention grooves needed (i.e., proximal divergence secondary to wide
structure at the marginal areas (not pulpally or axially); (2) extends faciolingual caries lesion extension), axial depth 0.5 mm inside (internal to)
the depth (pulpally, axially, or both) at the periphery of the prepara- the DEJ. Note that dashed lines on the occlusal surface only indicate the
tion to a prescribed, uniform dimension; (3) provides an initial position of the retention grooves associated with the facial and lingual
walls of the proximal preparation. The grooves do not extend onto the
form consistent with amalgam retention in the tooth; and (4)
occlusal surface.
establishes the preparation external walls in a form that will result
in a 90-degree amalgam margin upon restoration. he inal stage
of tooth preparation removes any remaining defect (caries lesion Initial Tooth Preparation
or old restorative material) and incorporates any additional prepara-
tion features (grooves, coves, slots, or pins) as needed to achieve All initial depths of a tooth preparation for amalgam relate to the
the appropriate retention and resistance forms. dentinoenamel junction (DEJ) except in the following two instances:
In academic institutions, assessing the tooth preparation after (1) when the occlusal enamel has become signiicantly thinner and
the initial preparation stage provides an opportunity to evaluate (2) when the preparation extends onto the root surface. he initial
a student’s knowledge and ability to extend the external walls depth pulpally is 0.2 mm inside (internal to) the DEJ or 1.5 mm
properly and establish proper initial depth. If the student were to as measured from the depth of the central groove (Fig. 10.7), whichever
remove an extensive caries lesion in its entirety before any evaluation, results in the greater thickness of amalgam. he initial depth of the
the attending faculty would not know whether the prepared depths axial wall is 0.2 mm inside the DEJ when retention grooves are not
were obtained because of appropriate caries lesion removal or used and 0.5 mm inside the DEJ when retention grooves are used
inappropriate overcutting of the tooth. (Fig. 10.8). he deeper extension allows placement of the retention
 CHAPTER 10 Clinical Technique for Amalgam Retoration 313

groove without undermining marginal enamel. Axial depths on the requirements for enamel strength must be combined with marginal
root surface should be 0.75 to 1 mm deep so as to provide room requirements for amalgam (90-degree butt joint) when establishing
for placement of retention grooves or coves. the periphery of the tooth preparation (Fig. 10.9).
he preparation extension is dictated primarily by the existing
caries lesion, old restorative material, or defect. Adequate extension
Outline Form to provide access for tooth preparation, caries lesion removal, matrix
he initial extension of the tooth preparation should be visualized placement, and amalgam insertion also must be considered. When
preoperatively by estimating the extent of the defect, the preparation making the preparation extensions, every efort should be made
form requirements of the amalgam, and the need for adequate to preserve the dentinal support (i.e., the strength) of cusps and
access and visibility to place the amalgam into the tooth. Enamel marginal ridges.
cavosurface margins must be left at 90 degrees or greater to limit When viewed from the occlusal, the facial and lingual proximal
the potential for enamel fracture. For enamel strength, the marginal cavosurface margins of a Class II preparation should be 90 degrees
enamel rods should be supported by sound dentin. These (i.e., perpendicular to a tangent drawn through the point of
extension facially and lingually) (see Fig. 10.9). In most instances,
proximal caries lesions severe enough to require surgical intervention
result in facial and lingual proximal walls that must be extended
into the facial or lingual embrasure. his extension provides adequate
access for performing the preparation (with decreased risk of
damaging the adjacent tooth), easier placement of the matrix band,
and easier condensation and carving of the amalgam. Such extension
provides “clearance” between the cavosurface margin and the
adjacent tooth (Fig. 10.10). Clearance also allows the operator to
conirm that no voids exist at the proximal margins of the inished
restoration. Occasionally the level of disease may not require
A extension of the proximal margins beyond the proximal contact.
This is especially helpful in areas that are more esthetically
demanding.

Clearance

90°

B
A Clearance

90°

Amalgam

C B
• Fig. 10.9 Proximal cavosurface margins. A, Facial and lingual proximal
Clearance
cavosurface margins prepared at 90-degree angles to a tangent drawn
through the point on the external tooth surface. B, A 90-degree proximal • Fig. 10.10 Proximal box preparation clearance of adjacent tooth. A,
cavosurface margin produces a 90-degree amalgam margin; C, 90-degree Occlusal view. B, Lingual view of a cross section through the central
amalgam margins. groove.
314 C HA P T E R 1 0 Clinical Technique for Amalgam Retoration

Factors dictating the outline form are presented in greater detail 90-degree enamel walls (representing a strong enamel margin) (see
in Chapter 4. hey include caries lesion, old restorative material, Fig. 10.9) that meet the inserted amalgam at a butt joint (enamel
inclusion of all of the defect, proximal or occlusal contact relation- and amalgam both having 90-degree margins).
ship, and the need for convenience form.
Reitance Form
Cavourface Margin Resistance form preparation features help the tooth and the restora-
Enamel must have a marginal coniguration of approximately 90 tion resist fractures caused by occlusal forces. Resistance features
degrees or greater, and amalgam must have a marginal coniguration that assist in preventing the tooth from fracturing include (1)
of approximately 90 degrees. Marginal wall conigurations with maintaining as much tooth structure as possible (preserving the
angles less than 90 degrees in enamel or amalgam are subject to dentin supporting cusps and marginal ridges); (2) having pulpal
fracture, as both of these materials are brittle. Preparation walls on and gingival walls prepared perpendicular to occlusal forces, when
the occlusal surface usually have obtuse enamel margins (representing possible; (3) having rounded internal preparation angles; (4) removing
the strongest enamel margin) and result in amalgam margins that unsupported or weakened tooth structure; and (5) placing slots
are slightly less than 90 degrees (Figs. 10.11 and 10.12). Rounding and pins into the tooth as part of the inal stage of tooth preparation,
of the central groove area when carving the occlusal amalgam enables when indicated. he placement of slots and pins is considered a
the marginal coniguration to be closer to 90 degrees (see Fig. secondary resistance form feature and is discussed in the section
10.12). Preparation walls on vertical aspect (in the occlusogingival Clinical Technique for Complex Amalgam Restorations. Resistance
axis) of the tooth (facial, lingual, mesial, or distal) should result in form features that assist in preventing the amalgam from fracturing
include (1) adequate thickness of amalgam (at least 1.5–2 mm in
areas of occlusal contact and 0.75 mm in axial areas); (2) amalgam
margin of 90 degrees; (3) boxlike preparation form, which provides
uniform amalgam thickness; and (4) rounded axiopulpal line angles
in Class II tooth preparations. Many of these resistance form features
may be achieved using the No. 330 or No. 245 bur.

Retention Form
Retention form preparation features retain (i.e., “lock”) the
restorative material in the tooth. For composite restorations,
adhesion (bonding) provides most of the needed retention. Amalgam
A
restorations must be mechanically retained in the tooth. Amalgam
retention form (Fig. 10.13) is provided by (1) preparation of the

a
Enamel

b ba
a
b
Dentin
B
• Fig. 10.11 Occlusal cavosurface margins. A, Tooth preparation.
B, Occlusal margin representing the strongest enamel margin. Full-length
enamel rods (a) and shorter enamel rods (b).
A B
a b

Retention
groove

DEJ

A B
• Fig. 10.12 Amalgam form at occlusal cavosurface margins. C
A, Amalgam carved too deep resulting in acute angles a and b and stress
concentrations within the amalgam, increasing the potential for fracture. • Fig. 10.13 Typical amalgam tooth preparation retention form features.
B, Amalgam carved with appropriate anatomy, resulting in an amalgam A and B, Occlusal convergence of prepared walls (primary retention form).
margin close to 90 degrees, although the enamel cavosurface margin is C, Retention grooves in proximal box (secondary retention form) if the
obtuse. proximal preparation is wide faciolingually.
 CHAPTER 10 Clinical Technique for Amalgam Retoration 315

vertical walls (especially facial and lingual walls) that converge

occlusally (i.e., primary retention); (2) retention features such as
grooves, coves, slots, and pins that are placed during the inal stage
of tooth preparation (i.e., secondary retention), and (3) engagement
of the inserted amalgam into any surface irregularities in the
preparation that may exist. Primary retention form features are
achieved by the orientation and type of the preparation instrument b
such as the No. 330 or No. 245 pear-shaped carbide bur or diamond
(see Fig. 10.7B). Secondary retention form features are discussed
in subsequent sections.
A B
Convenience Form
Convenience form includes features that allow adequate access • Fig. 10.14 Liner/Base application. A, Inserting resin-modiied glass
ionomer (RMGI) with periodontal probe. B, In moderately deep caries
and visibility of the operating site to facilitate tooth preparation removal, a base (b) thickness of 0.5 to 0.75 mm is indicated.
and restoration. Convenience form includes extension of the outline
form so that (1) the caries lesion may be accessed for removal, (2)
the matrix may be placed, and (3) amalgam may be inserted,
carved, and inished—all while maintaining resistance form.
RMGI base
Final Tooth Preparation
Removal of Defective Retorative Material and/
or Soft Dentin Calcium hydroxide
liner
Any old restorative material or soft dentin remaining after the initial
preparation will be located in the axial or pulpal walls (the extension
of the peripheral preparation margins should have already been to
sound tooth structure). Chapters 2 and 4 discuss (1) when to leave
or remove old restorative material, (2) how to remove remaining
soft dentin, and (3) what should be done to protect the pulp.
he removal of remaining soft dentin should be accomplished • Fig. 10.15 Placement of calcium hydroxide liner and RMGI base.
using the largest instrument that its the carious area because it is
least likely to penetrate the tooth in an uncontrolled manner. A
hand instrument is more reliable than a rotating bur for judging instrument and the same technique as described for the RMGI
the adequacy of removal of soft dentin. he removal of carious liner. he calcium hydroxide liner should be placed only over the
dentin should be stopped when the tooth structure feels irm unless deepest portion of the caries removal (nearest the pulp). A layer
exposure of the pulp becomes likely (see Chapter 2). his situation of RMGI liner should be used to cover the calcium hydroxide.67
often occurs before all lightly stained or discolored dentin is he entire dentin surface should not be covered (see Figs. 10.14
removed.61 and 10.15). he RMGI liner is recommended to cover the calcium
hydroxide to resist the forces of condensation and to prevent
dissolution over time by sealing the deeply excavated area.64 Pulp
Pulp Protection exposure will require a direct pulp cap with calcium hydroxide or
If the tooth preparation is of ideal or shallow depth, no liner or mineral trioxide aggregate (MTA), or endodontic treatment.68
base is indicated. In deeper caries removal (where the remaining
dentin thickness is judged to be 1–1.5 mm), a layer (i.e., Secondary Reitance and Retention Form
0.5–0.75 mm) of a resin-modiied glass ionomer (RMGI) material
should be placed (Fig. 10.14).62,63 he RMGI insulates the pulp Adequate resistance and retention form may no longer be present
from thermal changes, bonds to dentin, releases luoride, is strong in the tooth preparation after caries lesion removal has resulted in
enough to resist the forces of condensation, and reduces excessive loss of vertical wall height. herefore strategic features
microleakage.63-65 he RMGI is applied only over the deepest (such as the placement of grooves, coves, slots, pins) that enhance
portion of the caries removal. It should be placed in small increments the resistance and retention form are added. Usually, the larger
and should low when it is touched to the dentin surface. he the tooth preparation, the greater the need for secondary resistance
entire dentin surface should not be covered. Dentin peripheral to and retention forms.
the liner should be available for support of the restoration.66
For pulpal protection in very deep caries removal (where the Final Procedure: Debridement and Inpection
remaining dentin thickness is judged to be <0.5 mm and suspicion
of potential microscopic pulpal exposure is increased), a thin layer After the previous steps are performed, the completed tooth
(i.e., 0.5–0.75 mm) of a calcium hydroxide liner may be placed preparation should be cleaned of all debris (debridement) so that
(Fig. 10.15). he calcium hydroxide liner may elicit tertiary dentin a careful inspection may be accomplished. he usual procedure
formation if the original odontoblasts are no longer vital. If the in cleaning is to free the preparation of visible debris using short
calcium hydroxide liner is used, it is placed by using the same bursts of water spray from the air-water syringe followed by short
316 C HA P T E R 1 0 Clinical Technique for Amalgam Retoration

bursts with the air syringe. If debris still clings to the preparation, cross-links tubular luid proteins and, in the presence of HEMA,
it may be necessary to dislodge this material with an explorer, a forms lamellar plugs in the dentinal tubules.72 hese plugs are
small damp cotton pellet, or a commercially available applicator thought to be responsible for reducing the potential for rapid
tip (i.e., a “microbrush”) moistened with water. Excess water should tubular luid movement and, thereby, the sensitivity of dentin.
be removed so as to allow a clear ield for inspection. However, it his step may occur before or after the matrix application.
is important not to desiccate the tooth by overuse of air as this
may damage the odontoblasts associated with the desiccated tubules. Matrix Placement
he preparation should be viewed from all angles. Careful assessment
should be made to ensure that the depths are proper, the external A matrix primarily is used when a proximal surface is to be restored.
walls provide for enamel support and correct orientation for he objectives of a matrix are to provide proper contact, provide
amalgam (i.e., that the preparation is retentive and the resultant proper contour, conine the restorative material, and reduce the
restoration margins will not be prone to fracture), and the caries amount of excess material. For a matrix to be efective, it should
lesion has been removed as indicated. Preparation walls should be be easy to apply and remove, extend below the gingival margin
smooth and transitions should be gently rounded.69 he cavosurface enough that it can be engaged by a wedge, extend above the
margin should be precise and clearly visualized. adjacent marginal ridge height so as to allow for proper condensa-
tion, and resist deformation during material insertion.
In some clinical circumstances, a matrix may be necessary for
Preparation Deign Class I or V amalgam restorations. Matrix application, along with
Typical tooth preparation for amalgam has generally been referred wedging to increase interproximal space, may help protect the
to as conventional tooth preparation. A “box-only” tooth preparation adjacent tooth from being damaged during preparation.
is indicated if no occlusal caries lesion is present (i.e., only a proximal
caries lesion is present). Fig. 10.16 illustrates various preparation Mixing (Triturating) the Amalgam
designs. Appropriate details of speciic tooth preparations are
presented subsequently. Because of its superior clinical performance, high-copper amalgam
is recommended. Preproportioned, disposable capsules are available
in sizes ranging from 400 to 800 mg. Some precapsulated brands
General Concept Guiding Retoration require activation of the capsules before trituration. he speed and
With Amalgam time of trituration are factors that impact the setting reaction of
the material. Alterations in either may cause changes in the proper-
After tooth preparation, the tooth must be readied for the insertion ties of the inserted amalgam. Amalgam should be triturated (i.e.,
of amalgam. Disinfectants may be used, but are not considered mixed) according to the manufacturer’s directions. Correctly mixed
essential.70,71 However, it is highly recommended that a dentin amalgam should not be dry and crumbly; rather, it should retain
desensitizer (current commercial formulations contain 5% glutar- suicient “wetness” so as to aid in achieving a homogeneous and
aldehyde and 35% 2-hydroxyethyl methacrylate [HEMA] and well-adapted restoration.73 It is often necessary to make several
water) be placed on the prepared dentin per manufacturer’s mixes to complete the restoration, particularly for large
instructions (see Fig. 10.3). This type of dentin desensitizer preparations.

Inertion of the Amalgam

An amalgam carrier is used to transfer amalgam to the tooth
preparation. Increments extruded from the carrier should be smaller
(often only 50% or less of a full-carrier tip) for a small preparation,
particularly during the initial insertion. A lat-faced, circular or
elliptic condenser may be used to condense amalgam in the deeper
areas of the preparation. he principal objectives during the insertion
of amalgam are to condense the amalgam mass and to adapt it to
the preparation walls and the matrix (when used). horough
condensation is essential to produce a restoration free of voids,
and helps to reduce marginal leakage.74,75 Optimal condensation
is necessary to minimize the mercury content in the restoration,
which decreases corrosion and enhances restoration strength and
marginal integrity.75 Spherical amalgam is more easily condensed
than admixed (lathe-cut) amalgam, but some practitioners prefer
the handling properties of the admixed type. Condensation of
amalgam that contains spherical particles requires larger condensers
than are commonly used for admixed amalgam. Smaller condensers
tend to penetrate a mass of spherical amalgam, resulting in less
efective force to compact or adapt the amalgam within the prepara-
tion. In contrast, smaller condensers are indicated for the initial
A B increments of admixed amalgam because it is more resistant to
• Fig. 10.16 Types of amalgam tooth preparations. A, Conventional. condensation pressure. his is because the area of a circular con-
B, Box only. denser face (nib) increases by the square of the diameter; doubling
 CHAPTER 10 Clinical Technique for Amalgam Retoration 317

the diameter requires four times more force for the same pressure
per unit area. Each portion must be thoroughly condensed prior
Discoid-cleoid
to placement of the next increment. Each condensed increment
should ill only one third to one half the preparation depth. Each
condensing stroke should overlap the previous condensing stroke
to ensure that the entire mass is well condensed.
Lateral condensation (facially, lingually, and proximally directed
condensation) is important in the proximal box portions of prepara- Amalgam
tions to ensure conluence of the amalgam with the margins, the
elimination of voids, and an adequate proximal contact. Generally,
smaller amalgam condensers are used irst, which allows the amalgam
to be properly condensed into the internal line angles and secondary
retention features. Subsequently, larger condensers are used.
Amalgam preparations should be somewhat overilled to ensure
adequate condensation on the occlusal surface. he condensation
of a mix should be completed within the time speciied by the
manufacturer (usually 2.5 to 3.5 minutes). Otherwise crystallization • Fig. 10.17 Carving the occlusal margins.
of the unused portion will be too advanced to react properly with
the condensed portion. he mix should be discarded if it becomes
dry, and another mix quickly made to continue the insertion.

Precarve Burnihing
To ensure that the marginal amalgam is well condensed before
carving, the overpacked amalgam should be burnished immediately
with a large burnisher, using heavy strokes mesiodistally and facio-
lingually, a procedure referred to as precarve burnishing. Precarve
burnishing is useful to inalize the condensation, remove excess
mercury-rich amalgam, and initiate the carving process. To maximize
its efectiveness, the burnisher head should be large enough that
in the inal strokes it contacts the cusp slopes but not the preparation
margins. Precarve burnishing produces denser amalgam at the
margins of the occlusal preparations restored with high-copper • Fig. 10.18 Deining the marginal ridge and the occlusal embrasure
amalgam alloys and initiates contouring of the restoration.76,77 with an explorer.

Carving the Amalgam the primary grooves, fossae, and cuspal inclines. he Hollenback
he following discussion of carving (and shaping) of amalgam carver is also useful for carving these areas.
assumes the use of sharp carving instruments. All carving instruments he reproduction of grooves and fossae is necessary to provide
dull with repeated use and sterilization cycles and, as a result, lose appropriate mastication and sluiceways for the escape of food from
their eiciency. Carving a freshly condensed amalgam, which is the occlusal table. he mesial and distal fossae are carved to be
setting and steadily getting harder, with a dull instrument requires inferior to the marginal ridge height, helping limit the potential
the use of ever-increasing pressure on the instrument and increases for food to be wedged into the occlusal embrasure. Having rounded
the likelihood of losing control (slipping) and/or increasing the and relatively shallow occlusal anatomy also helps achieve a 90-degree
amount of time required to complete the carving. Always use sharp amalgam margin on the occlusal surface and to ensure adequate
carving instruments! occlusogingival dimension of the inal amalgam restoration for
he amalgam material selected for the restoration has a speciic strength (see Fig. 10.12B).
setting time. After precarve burnishing has been accomplished, For multiple surface restorations (which require use of a matrix),
the remainder of the accessible restoration must be contoured to the initial carving of the occlusal surface should be rapid, concentrat-
achieve proper form and, as a result, function. he insertion ing primarily on the marginal ridge height and occlusal embrasure
(condensation) and carving of the material must occur before the areas. Occlusal embrasure areas are developed with a thin explorer
material has hardened so much that it becomes uncarvable. tip or carving instrument by mirroring the contours of the adjacent
tooth. he explorer tip is pulled along the inside of the matrix
band, creating the occlusal embrasure form. When viewed from
Occlual Area the facial or lingual direction, the embrasure form created should
A discoid–cleoid instrument may be used to carve the occlusal be identical to that of the adjacent tooth, assuming that the adjacent
surface of an amalgam restoration. he rounded end (discoid) is tooth has appropriate contour. Likewise, the height of the amalgam
positioned on the unprepared enamel adjacent to the amalgam marginal ridge should generally be the same as that of the adjacent
margin and pulled parallel to the margin (Fig. 10.17). his removes tooth (Figs. 10.18 and 10.19). If both these areas are developed
any excess at the margin while not allowing the marginal amalgam properly, the potential for fracture of the marginal ridge area of
to be carved below the preparation margins (i.e., “submarginated”). the restoration while checking the occlusion is signiicantly reduced.
he pointed end (cleoid) of the instrument may be used to deine Placing the initial carving emphasis on the occlusal areas for a
318 C HA P T E R 1 0 Clinical Technique for Amalgam Retoration

A B C
• Fig. 10.19 Proximal contour. A, Correct proximal contour. B, Incorrect marginal ridge height and
occlusal embrasure form. C, The occlusogingival proximal contour is too straight, the contact is too high,
and the occlusal embrasure form is incorrect.

Blade

Excess
• Fig. 10.20 Positioning of the carving instrument to prevent overcarving
amalgam and to develop the desired gingival contours.

• Fig. 10.21 Gingival excess may be removed with amalgam knives.

large restoration permits the operator to remove the matrix more
quickly so as to carve any extensive axial surfaces of the restoration,
especially the proximal areas. Some of these areas may be relatively 10.22). he knife is positioned below the gingival margin and
inaccessible and must be carved while the amalgam material is drawn occlusally to carefully shave of excess, to reine the proximal
still not fully set. Remaining necessary carving or contouring on contour (below the contact) and the gingival embrasure form. he
the occlusal surface may be done later, and if the amalgam is too sharp tip of the knife also is beneicial in developing the facial and
hard to carve, the use of rotary instruments in the handpiece may lingual embrasure forms. Care must be exercised in not carving
be required. away any of the contour necessary to create the desired proximal
contact.
Development of proper proximal contour and contact is
Facial and Lingual Area important for the physiologic health of interproximal soft tissue.
Most facial and lingual areas are accessible and may be carved Likewise, ensuring a smooth junction between the tooth and the
directly. he side of an explorer tine may be very efective in creating amalgam is important. An amalgam overhang (excess of amalgam)
correct contours when the amalgam is early in its setting reaction. may result in compromised gingival health. Voids at the cavosurface
A Hollenbeck carver or base of the amalgam knife (scaler 34/35) margins may result in recurrent caries lesion formation.
is also useful for carving these areas. With regard to the cervical he proximal portion of the carved amalgam is evaluated by
areas, it is important to remove any excess and develop the proper visual assessment (relecting light into the contact area from the
contour of the restoration, which is usually convex. he convexity lingual and occlusal perspectives to conirm the dimensions and
is developed by using the occlusal and gingival unprepared tooth location of the proximal contact) and placement of very thin dental
structure as guides for initiating the carving (Fig. 10.20). he loss through the contact area. If dental loss is used, it must be
marginal areas are blended together, resulting in the desired convexity used judiciously, ensuring that amalgam in the contact area is not
and providing a physiologic contour that promotes the health of inadvertently removed. A piece of loss may be inserted through
adjacent gingival tissue. the contact and into the gingival embrasure area by initially wrapping
the loss around the adjacent tooth and exerting pressure on that
tooth rather than the restored tooth while moving the loss through
Proximal Embraure Area the contact area. When the loss is into the gingival embrasure
he initial development of the occlusal embrasure of the proximal area, it is wrapped around the restored tooth and moved occlusally
surface while the matrix is still in place has already been described. and gingivally to determine whether excess exists and to smooth
After removal of the matrix, the amalgam knife (or scaler 34/35) the proximal amalgam material. If excess material is detected along
is an excellent instrument for removing proximal excess and the gingival margin, the amalgam knife should again be used until
developing proximal contours and embrasures (Figs. 10.21 and a smooth margin is created.
 CHAPTER 10 Clinical Technique for Amalgam Retoration 319

A B C
• Fig. 10.22 Removal of gingival excess of amalgam. A, Excess of amalgam (arrowhead) at the gingival
corner of the restoration. B, Use of the amalgam knife for removal of gingival excess. C, Gingival corner
of restoration with excess removed.

(by visual estimation), the high spot(s) should be reduced by

Postcarve Burnishing approximately that amount. his observation may expedite the
Some operators prefer to postcarve burnish the amalgam surface occlusal adjustment compared with making an insuicient adjust-
by using a small burnisher. Postcarve burnishing is done by lightly ment and having to repeat closure-and-carving numerous times.
rubbing the carved surface with a burnisher of suitable size and he sequence of closure, observation, and carving is repeated until
shape to improve smoothness and produce a satin (not shiny) the appropriate surfaces of opposing teeth are touching.
appearance. he surface should not be rubbed hard enough to Occlusal contacts on a cuspal incline or ridge slope are undesir-
produce grooves in the amalgam. Postcarve burnishing may improve able because they cause a delective lateral force on the tooth.
the marginal integrity of low- and high-copper amalgams and may hese should be adjusted until the resulting contact is stable (i.e.,
improve the smoothness of the restoration.78-80 Postcarve burnishing the occlusal contact should be perpendicular to the occlusal load
in conjunction with precarve burnishing may serve as a substitute where possible in maximum intercuspation, or, in other words,
for conventional polishing.80 the occlusal force should be parallel to the long axis of the tooth).
To this point in the procedure, the patient has been instructed
Evaluation of Occlual Contact Area on to close vertically into maximum intercuspation (i.e., “bite together
on your back teeth”). After replacing the articulating paper over
the Retoration the tooth, the patient is asked to occlude lightly and to slide the
After completion of the carving and the removal of the rubber teeth lightly from “side to side” to identify excursive interferences
dam, the occlusal contacts on the restoration must be evaluated. and “front to back” to identify protrusive interferences (see Chapter
Even if the carving has been carefully accomplished, the restoration 1). Any additional occlusal marks are evaluated, and undesirable
occasionally is “high,” indicating premature occlusal contact. A contact areas (interferences) are eliminated. Note that amalgam
piece of articulating paper is placed over the restoration and adjacent restorations carved completely out of occlusion (i.e., that are “over-
teeth, and the patient is instructed to close gently into occlusion. carved”) may allow supraeruptive tooth movement resulting in
It is essential that the teeth be completely dry for proper marking with undesirable tooth contacts and this, too, should be avoided. Finally,
articulating paper. he patient is advised not to bite irmly because the patient should be cautioned to protect the newly condensed
of the danger of fracturing the restoration, which is weak at this restoration by not using it to chew irm food for 24 hours.
stage. he operator should visually assess the contact potential of
the restored tooth and the extent of closure. If local anesthesia is Finihing and Polihing of the Amalgam
still present, it may be diicult for the patient to tell when the
teeth are in contact. After the patient has reopened the mouth Most amalgams do not require further inishing and polishing.
and the articulating paper is removed, the following two features hese procedures are occasionally necessary, however, to (1) reine
of the occlusal relationship suggest that the restoration is high: (1) the anatomy, contours, and marginal integrity; and (2) reine the
Cusp tips of adjacent teeth are not in occlusal contact when it is surface texture of the restoration. Additional inishing and polishing
known from the preoperative occlusal assessment that they should procedures for amalgam restorations are not attempted within 24
be touching, and (2) an opposing cusp prematurely occludes with hours of insertion because crystallization of the restoration is
the new restoration. incomplete.73 If used, these procedures are often delayed until all
Contact areas on the amalgam should be assessed by the color of the patient’s amalgam restorations have been placed, rather than
imparted by the articulating paper. Deeply colored areas (heavy inishing and polishing periodically during the course of treatment.
contacts) and those with light-colored centers (even heavier contacts) An amalgam restoration is less prone to tarnish and corrosion if
are reduced until all markings are uniformly of a light hue, and a smooth, homogeneous surface is achieved.81-83 Polishing of high-
contacts are noted on adjacent teeth (Fig. 10.23). Heavy occlusal copper amalgams is less important than it is for low-copper
contacts are commonly referred to as “prematurities” or “high amalgams because high-copper amalgams are less susceptible to
spots.” Observing the bite opening between nearby teeth when tarnishing and marginal breakdown.56,82-87
the restoration is in contact indicates how much occlusal adjustment he inishing procedure may be initiated by use of a green
is indicated. For example, if the adjacent teeth are 0.5 mm apart carborundum or white alumina stone. (Fig. 10.24A). he green
320 C HA P T E R 1 0 Clinical Technique for Amalgam Retoration

A B
• Fig. 10.23 Occluding the restoration. A, Heavy occlusal contacts on new amalgam should be
adjusted. Articulating paper marks heavy contacts as dark areas, and it marks very heavy contacts as
dark areas with light-colored, potentially shiny, centers. B, Amalgam should not be carved out of occlu-
sion. Rather, it should have light occlusal contact or contacts, as indicated by faint markings.

stone is more abrasive than the white stone; the tip of either stone disintegration (which may occur at high rotational speeds) and
may be blunted on a diamond wheel before use. his helps prevent the danger of frictional temperature elevation of the restoration
marring the center of the restoration while the margins are being and the tooth. Temperature above 140°F [>60°C] is able to cause
adjusted. During the surfacing of amalgam, the stone’s long axis is irreparable damage to the pulp, the restoration, or both. When
held at a 90-degree angle to the margins. Reduction of any occlusal overheated, the amalgam surface appears cloudy, even though it
contact should be avoided. After the stone is used, the margins may have a high polish. his cloudy appearance indicates that
should be reevaluated with the tine of an explorer and any additional mercury has been brought to the surface, which results in increased
discrepancies removed. he surface may be smoothed further using corrosion of the amalgam and loss of strength.73
light pressure with an appropriate inishing bur (see Fig. 10.24B). Polishing with the coarse abrasive rubber point will result in a
A large, round inishing bur is generally used for this inishing step. moderately polished surface. No deep scratches should remain on
If the groove and fossa features are not suiciently deined, a small the amalgam surface. After the area is washed free of abrasive
round inishing bur also may accentuate them without eliminating particles and dried, a high polish may be imparted to the restoration
the occlusal contact areas. he long axis of the bur or stone should with a series of medium grit and ine-grit abrasive points (see Fig.
be at a ~45-degree angle to the margin to allow the unprepared 10.24F). As with the more abrasive points, the iner abrasive points
tooth structure to guide the bur and prevent unnecessary removal must be used at a low speed. If a high luster does not appear
of amalgam (see Fig. 10.24C). A smooth surface should be achieved within a few seconds, the restoration requires additional polishing
before the polishing procedure is initiated. he inishing bur should with the more abrasive points. he system illustrated in Fig. 10.24
remove the minor scratches that resulted from use of the green or includes coarse-grit, medium-grit, and ine-grit rubber abrasive
white stone. Often, however, these scratches can be removed only points. Using these points in sequence, from coarse to ine, produces
with the use of rubber abrasive points. an amalgam surface with a brilliant luster (see Fig. 10.24G). As
he polishing procedure is initiated by using a coarse, rubber an alternative to rubber abrasive points, inal polishing may be
abrasive point at low speed and air-water spray to produce an accomplished using a rubber cup with lour of pumice followed
amalgam surface with a smooth, satin appearance (see Fig. 10.24D by a high-luster agent such as precipitated chalk. Finishing and
and E). If the amalgam surface does not exhibit this appearance polishing of older, existing restorations may be performed to improve
after only a few seconds of polishing, the surface was too rough their contour, margins, surface, or anatomy, when indicated (Fig.
at the start. In this instance, resurfacing with a inishing bur is 10.25).
necessary, followed by the coarse, rubber abrasive point to develop hese procedures should not leave the restoration undercontoured
the satiny appearance. It is important that the rubber points be and should not alter the carefully designed occlusal contacts. he
used at low speed (≤6000 revolutions per minute [rpm]) or just tip of an explorer should pass from the tooth surface to the restora-
above “stall out” speed so as to limit the danger of point tion surface (and vice versa), without jumping or catching, thus
A B

C D

F G
• Fig. 10.24 Polishing the amalgam. A, When necessary, a carborundum or ine-grit alumina stone is
used to develop continuity of surface from the tooth to the restoration. B, The restoration is surfaced with
a round inishing bur. C, The stone’s long axis or the bur’s long axis is held at a right angle to the margin.
D, Polishing is initiated with a coarse rubber abrasive point at low speed. E, The point should produce a
smooth, satin appearance. F, A high polish is obtained with medium-grit and ine-grit abrasive points.
G, Polished restoration. (Courtesy Aldridge D. Wilder, DDS.)
322 C HA P T E R 1 0 Clinical Technique for Amalgam Retoration

A B
• Fig. 10.25 A, Existing amalgam restoration exhibiting marginal deterioration and surface roughness.
B, Same restoration after inishing and polishing.

A B

C
• Fig. 10.26 Clinical examples of Class I, II, and VI amalgam restorations. A, Class I amalgam in the
occlusal surface of the irst molar. B, Class II amalgams in a premolar and molar. C, Class VI amalgams
in premolars.

verifying continuity of contour across the margin. Every efort to entirely within the existing amalgam restoration. If necessary, another
avoid removal of adjacent tooth structure should be made. matrix must be placed. A new mix of amalgam may be condensed
directly into the defect.
Repairing an Amalgam Retoration
If an amalgam restoration fractures during insertion, generally all Clinical Technique for Cla I
of the inserted amalgam must be removed and new amalgam Amalgam Retoration
condensed. If a small portion of amalgam fractures during insertion
and the amalgam is still carvable, it may be possible to apply and his section describes the use of amalgam for Class I restorations.
condense newly triturated amalgam to repair the afected area. If Class I restorations restore defects on the occlusal surfaces of
a small void in the amalgam is discovered after the matrix is removed, posterior teeth, the occlusal thirds of the facial and lingual surfaces
for example, and if the amalgam is still carvable and the area is of molars, and the lingual surfaces of maxillary anterior teeth
accessible, any poorly condensed amalgam in the void should be (Fig. 10.26).
removed with an explorer or other instrument, and the void repaired he procedural description for a small (i.e., “conservative”) Class
with newly triturated amalgam. In cases where a new mix of I amalgam restoration simply and clearly presents the basic informa-
amalgam is added to carvable existing amalgam, the “new” amalgam tion relating to the entire amalgam restoration technique, including
will adhere to the “old.” tooth preparation and placement and contouring of the restoration.
If a repair needs to be made to set, uncarvable amalgam, the his basic procedural information may be expanded to describe
defective area may be re-prepared as if it were a small restoration. Class I amalgam restoration of lesions/defects of all sizes. he maxillary
Appropriate depth and retention form must be generated, sometimes irst premolar is used for illustration in this section.
 CHAPTER 10 Clinical Technique for Amalgam Retoration 323

3 mm

330 245

A B 0.8 mm C
• Fig. 10.27 Class I preparation outline. A, Ideal outline includes all carious occlusal pits and issures.
B, Dimensions of head of a No. 245 bur. C, No. 330 and No. 245 burs compared.

Initial Clinical Procedures form principles that are basic to all amalgam tooth preparations
A preoperative assessment of the occlusal relationship of the involved of occlusal surfaces (Fig. 10.27A). hese principles allow margins
and adjacent teeth is necessary. After administration of local to be positioned in areas that are sound and subject to minimal
anesthetic, isolation of the operating ield with the rubber dam is occlusal loading while maintaining the strength and health of the
recommended.73,88 he rubber dam may be applied in the few tooth by conserving uncompromised tooth structure. he resistance
minutes necessary for onset of profound anesthesia before initiating principles are as follows:
the tooth preparation. Rubber dam isolation is especially indicated 1. Extending around the cusps to conserve tooth structure and
when removing deep caries (judged to be <1 mm from the pulp), prevent the internal line angles from approaching the pulp horns
during amalgam condensation, and for mercury hygiene. he rubber 2. Keeping the facial and lingual margin extensions as minimal
dam should be used for isolation of the operating site when a as possible between the central carious issure and the cusp tips
caries lesion is extensive. If caries removal exposes the pulp, pulp 3. Extending the outline to include issures, placing the margins
capping may be more successful if the site is isolated with a properly on relatively smooth, sound tooth structure
applied rubber dam. In addition, the dam prevents moisture 4. Minimally extending into the marginal ridges (only enough to
contamination of the amalgam mix during insertion.60 For a single include the defect) without removing dentinal support
maxillary tooth, where caries is not extensive, adequate control of 5. Eliminating a weak wall of enamel by joining two outlines that
the operating ield may also be achieved with cotton rolls and come close together (i.e., <0.5 mm apart)
high-volume evacuation. 6. Extending the outline form to include enamel undermined by
the caries lesion
Tooth Preparation for Cla I Amalgam 7. Using enameloplasty on the terminal ends of shallow issures
to conserve tooth structure
Retoration 8. Establishing an optimal, conservative depth of the pulpal wall
his section describes the speciic technique for preparing the A No. 245 bur, with a head length of 3 mm and a tip diameter
tooth for a Class I amalgam restoration. It is divided into initial of 0.8 mm, or a smaller No. 330 bur is recommended to prepare
and inal stages. the Class I tooth preparation (see Fig. 10.27B and C). he silhouette
of the No. 245 bur reveals sides slightly convergent toward the
Initial Tooth Preparation shank. his produces an occlusal convergence of the facial and
Initial tooth preparation is deined as establishing the outline form lingual preparation walls, providing adequate retention form for
by extension of the external walls to sound tooth structure while the tooth preparation. he slightly rounded corners of the end of
maintaining a speciied, limited depth (usually just inside the DEJ) the No. 245 bur produce slightly rounded internal line angles that
and providing resistance and retention forms. he outline form render the tooth more resistant to fracture from occlusal force.89
for the Class I occlusal amalgam tooth preparation should include he No. 330 bur is a smaller and pear-shaped version of the
only the defective occlusal pits and issures (in a way that sharp, No. 245 bur and is also indicated for amalgam preparations (see
angular, abrupt transitions in the marginal outline are avoided). Fig. 10.27C).
Commonly, but not always, the marginal outline for maxillary Class I occlusal tooth preparation is begun by entering the
premolars is butterly shaped because of extension to include the deepest or most carious pit with a “punch cut” using the No. 245
developmental issures facially and lingually. he ideal outline form carbide bur at high speed with air-water spray. A punch cut is
for an amalgam restoration incorporates the following resistance performed by orienting the bur such that its long axis parallels
324 C HA P T E R 1 0 Clinical Technique for Amalgam Retoration

A B

245

245

Facial
cavosurface
margin

Bur blade depth in

relation to central fissure
(1.5 mm, or 1/2 length
of bur head); in relation
to cavosurface margin
Facial (may be 2 mm, or 2/3
wall length of bur head)

Excised central groove

D E
C
• Fig. 10.28 A, No. 245 bur oriented parallel to long axis of tooth crown for entry as viewed from lingual
aspect. B, The bur positioned for entry as viewed from the distal aspect. C, The bur is positioned over
the most carious pit (distal) for entry. The distal aspect of the bur is positioned over the distal pit.
D, Mesiodistal longitudinal section. Relationship of head of No. 245 bur to excised central issure and
cavosurface margin at ideal pulpal loor depth, which is just inside the DEJ. E, Faciolingual longitudinal
section. Dotted line indicates the long axis of tooth crown and the direction of the bur.

the long axis of the tooth crown (Fig. 10.28A and B). he bur is central issure (see Fig. 10.28D and E). he depth of the preparation
inserted directly into the defective pit. When the pits are equally is modiied as needed so that the pulpal wall is established 0.1 to
defective, the distal pit should be entered as illustrated. Entering 0.2 mm into dentin. In other words, the depth of the prepared
the distal pit irst provides increased visibility for the mesial exten- external walls should be 1.5 to 2 mm (“just inside the DEJ”) (see
sion. he bur should be positioned such that its distal aspect is Fig. 10.28D and E), depending on the cuspal incline. he length
directly over the distal pit, minimizing extension into the marginal of the blades of an unfamiliar bur should be measured before it
ridge (see Fig. 10.28C). he bur should be rotating when it is is used as a depth gauge.
applied to the tooth and should not stop rotating until it is removed Distal extension into the distal marginal ridge to include a
from the tooth. On posterior teeth, the approximate depth of the issure or caries occasionally requires a slight tilting of the bur
DEJ is located at 1.5 to 2 mm from the occlusal surface. As the distally (≤10 degrees). his creates a slight occlusal divergence to
bur enters the pit, an initial target depth of 1.5 mm should be the distal wall to prevent undermining the marginal ridge of its
established. his is one half the length of the cutting portion of dentin support (Fig. 10.29A–C). Because the facial and lingual
the No. 245 bur. he 1.5-mm pulpal depth is measured at the prepared walls converge, this slight divergence does not compromise
 CHAPTER 10 Clinical Technique for Amalgam Retoration 325

1.6 mm

A B

C D
E
• Fig. 10.29 A, Enter the pit with a punch cut to just inside the DEJ (depth of 1.5–2 mm or one half
to two thirds the head length of the No. 245 bur). The 1.5-mm depth is measured at central issure; the
measurement of same entry cut at the prepared external wall is 2 mm. B, Incline the bur distally to
establish proper occlusal divergence to distal wall to prevent removal of the dentin supporting the marginal
ridge enamel when the pulpal loor is in dentin, and distal extension is necessary to include a issure or
caries lesion. For such an extension on premolars, the distance from the margin to the proximal surface
(i.e., imaginary projection) must not be less than 1.6 mm (i.e., two diameters of bur end). C, Occlusal
view of the initial tooth preparation that has mesial and distal walls that diverge occlusally. D, Distofacial
and distolingual issures that radiate from the pit are included before extending along the central issure.
E, Mesiodistal longitudinal section. The pulpal loors are generally lat but may follow the rise and fall of
the occlusal surface.

the overall retention form. For premolars, the distance from the however, consideration should be given to changing to a bur of
margin of such an extension to the proximal surface usually should smaller diameter or to using enameloplasty. Both of these approaches
not be less than ~1.6 mm, or two diameters of the end of the No. conserve the tooth structure and therefore minimize weakening
245 bur (see Fig. 10.29B) measured from a tangent to the proximal of the tooth.
surface (i.e., the proximal surface height of contour). For molars, he bur’s orientation and depth are maintained while extending
this minimal distance is ~2 mm. along the central issure toward the mesial pit, following the DEJ
Minimal distal (or mesial) extension often does not require (see Fig. 10.29D and E). When the central issure has minimal
changing the orientation of the bur’s axis from being parallel to caries, one pass through the issure at the prescribed depth provides
the long axis of the tooth crown. In this case, the mesial and distal the desired minimal width to the isthmus. Ideally the width of
walls are parallel to the long axis of the tooth crown (or slightly the isthmus should be just wider than the diameter of the bur. It
convergent occlusally) (see Fig. 10.29D and E). is well established that a tooth preparation with a narrow occlusal
While maintaining the bur’s orientation and depth, the prepara- isthmus is less prone to fracture.90,91 As previously described for
tion is extended distofacially or distolingually to include any issures the distal margin, the orientation of the bur should not change
that radiate from the pit (see Fig. 10.29D). When these issures as it approaches the mesial pit if the mesial extension is minimal.
require extensions of more than a few tenths of a millimeter, If the issure extends farther onto the marginal ridge, the long axis
326 C HA P T E R 1 0 Clinical Technique for Amalgam Retoration

No. 245 bur

b a

1.6
1.6 mm
mm Correct Correct Incorrect

Contact
area

A B C
• Fig. 10.30 The direction of the mesial and distal walls is inluenced by the remaining thickness of the
marginal ridge as measured from the mesial or distal margin (a) to the proximal surface (i.e., imaginary
projection of proximal surface) (b). A, Mesial and distal walls should converge occlusally when the distance
from a to b is greater than 1.6 mm. B, When the operator judges that the extension will leave only 1.6-mm
thickness (two diameters of No. 245 bur) of marginal ridge (i.e., premolars), the mesial and distal walls
must diverge occlusally to conserve ridge-supporting dentin. C, Extending the mesial or distal walls to a
two-diameter limit without diverging the wall occlusally undermines the marginal ridge enamel.

a
Enamel

Dentin
A B
• Fig. 10.31 A and B, The ideal and strongest enamel margin is formed
by full-length enamel rods (a) resting on sound dentin supported on the
preparation side by shorter rods, also resting on sound dentin (b).

of the bur should be changed to establish a slight occlusal divergence

to the mesial wall if the marginal ridge would be otherwise
undermined of its dentinal support. Fig. 10.30 illustrates the correct
and incorrect preparation of the mesial and distal walls. he • Fig. 10.32 Mesiodistal longitudinal section showing example of the
remainder of any occlusal enamel defects is included in the outline, pulpal loor in dentin and the caries lesion that is exposed after the initial
and the facial and lingual walls are extended, if necessary, to remove tooth preparation. The caries lesion is surrounded by sound dentin on the
enamel undermined by the caries lesion.92 he strongest and ideal pulpal loor for the resistance form.
enamel margin should be composed of full-length enamel rods
attached to sound dentin, supported on the preparation side by
shorter rods that are also attached to sound dentin (Fig. 10.31). his completes the initial amalgam preparation for a Class I
he Class I tooth preparation should have an outline form with caries lesion. he initial preparation should ensure that all the
gently lowing curves and distinct cavosurface margins. A faciolingual caries lesion is removed from the DEJ, resulting in a very narrow
width of no more than 1 to 1.5 mm and a depth of 1.5 to 2 mm peripheral seat of healthy dentin on the pulpal wall surrounding
are considered ideal, but this goal is subject to the extension of any remaining caries located in the center of the pulpal wall. For
the caries lesion. he pulpal loor, depending on the enamel thick- the initial tooth preparation, the pulpal wall should remain at the
ness, is almost always in dentin (see Fig. 10.29C and E). Although initial ideal depth, even if any restorative material or soft caries
conservation of the tooth structure is important, the convenience lesion remains in the pulpal wall (Fig. 10.32). Remaining caries
form requires that the extent of the preparation be adjusted to (and, if present, old restorative material) is removed during the
provide adequate access and visibility. inal tooth preparation.
 CHAPTER 10 Clinical Technique for Amalgam Retoration 327

80° 100°

A B C D
• Fig. 10.33 Enameloplasty. A, Developmental defect at terminal end of issure. B, Fine-grit diamond
inishing instrument in position to remove the defect. C, Smooth surface after enameloplasty. D, The
cavosurface angle should not exceed 100 degrees, and the margin–amalgam angle should not be less
than 80 degrees. Enamel external surface (e) before enameloplasty.

Primary resistance form is provided by the following:

1. Suicient area of relatively lat pulpal loor in sound tooth
structure (i.e., the “peripheral seat”) to resist forces directed in
the long axis of the tooth and to provide a horizontal area for
the restoration
2. Minimal extension of external walls (to conserve tooth strength)
3. Strong, ideal enamel margins
4. Suicient depth (i.e., 1.5 mm) for adequate thickness of the
restoration, providing resistance to fracture
he slight occlusal convergence of two or more opposing, external
walls provides the primary retention form.
Usually, the No. 245 bur is used for extensions into the mesial
and distal issures. During such extensions, the remaining depth
of the issure may be viewed in cross section by looking at the
wall being extended. When the remaining issure is no deeper than
• Fig. 10.34 Mesial issure that cannot be eliminated by enameloplasty
one quarter to one third the thickness of enamel, enameloplasty may be included in the preparation if the margins are able to be lingual of
is indicated. Enameloplasty refers to eliminating the developmental the occlusal contact.
fault by removing it with the side of an appropriately shaped rotary
inishing instrument, leaving a smooth surface (Fig. 10.33A–C).
his procedure frequently reduces the need for further extension. A tooth may be found to have a large or “extensive” Class I caries
he extent to which enameloplasty should be used cannot be lesion. A lesion is considered extensive if the distance between soft
determined exactly until the process of extending into the issured dentin and the pulp is judged to be less than 1 mm or when the
area occurs, at which time the depth of the issure into enamel faciolingual extent of the defect has involved much of the cuspal
may be observed. he surface left by enameloplasty should meet inclines. In this case, selective removal of soft dentin and insertion
the tooth preparation wall, preferably with a cavosurface angle no of a liner, if needed, may precede the establishment of outline,
greater than approximately 100 degrees; this would produce a resistance, and retention forms. his approach protects the pulp as
distinct margin for amalgam of no less than 80 degrees (see Fig. early as possible from any additional insult that may occur during
10.33D). If enameloplasty is unsuccessful in eliminating a mesial tooth preparation. Normally, however, the outline, primary resistance,
(or distal) issure that extends to the crest of a marginal ridge or and primary retention forms are established through proper orientation
beyond, three alternatives exist: of the No. 245 bur and appropriate extension of the preparation.
1. Make no further change in the outline form. As is the case for smaller caries lesions, an initial depth to reach the
2. Extend through the marginal ridge when margins would be DEJ (measured approximately 1.5 mm at any pit or issure and
lingual to the contact (Fig. 10.34). 2 mm on the prepared external walls) should still be established and
3. Include the fissure in a conservative Class II tooth maintained. he preparation is extended laterally at the DEJ to
preparation. remove all enamel undermined by the caries lesion by alternately
he irst alternative usually should be strongly considered except cutting and examining the lateral extension of the lesion. For a caries
in patients at high risk for caries. Enameloplasty is not indicated lesion extending up the cuspal inclines, it may be necessary to alter
if an area of occlusal contact is involved. In this case, the choices the bur’s long axis to prepare a 90- to 100-degree cavosurface angle
are either to consider the preparation completed (an option for while maintaining the initial depth (Fig. 10.35). If not, an obtuse
patients at low risk for caries) or to extend the preparation to cavosurface angle may remain (resulting in an acute, or weak, amalgam
include the issure as previously described. margin), or the pulpal loor (over the pulp horns) may be prepared
328 C HA P T E R 1 0 Clinical Technique for Amalgam Retoration

too deeply. Primary resistance form is obtained by extending the retention form may result from undercut areas that are occasionally
outline of the tooth preparation to include only undermined and left in dentin (and that are not illed in by a liner or base) after
defective tooth structure while preparing strong enamel walls and peripheral removal of soft dentin. When extending the outline form,
allowing strong cuspal areas to remain. Primary retention form is enameloplasty should be used in any indicated area (as described
obtained by the occlusal convergence of the enamel walls. Secondary previously and in detail in Chapter 4).
When the defect extends to more than one half the distance
between the primary groove and a cusp tip, reducing the cuspal
tooth structure and restoring it with amalgam (also referred to as
“capping the cusp”) may be indicated as discussed in Clinical
Technique for Complex Amalgam Restorations. When the distance
is two thirds, cusp reduction and coverage is usually required because
of the risk of cusp fracture during subsequent functional occlusal
loading. Fig. 10.36 illustrates examples of large (extensive) Class
80° I amalgam preparation outlines.

Final Tooth Preparation

he inal tooth preparation includes (1) removal of remaining
defective enamel and soft dentin on the pulpal loor as indicated;
(2) pulp protection, where indicated; (3) procedures for inishing
the external walls; and (4) inal procedures of debridement (cleaning)
and inspecting the preparation.
If several enamel pit-and-issure remnants remain in the loor,
or if a central issure remnant extends over most of the loor, the
loor should be deepened with the No. 245 bur to eliminate the
• Fig. 10.35 Initial tooth preparation with an extensive caries lesion. defect or to uncover the caries lesion to a maximum preparation
When extending laterally to remove enamel undermined by the caries depth of 2 mm (Fig. 10.37). If these remnants are few and small,
lesion, the bur’s long axis is altered to prepare a 90- to 100-degree cavo- they may be removed with an appropriate carbide bur (Fig. 10.38).
surface angle. A 100-degree cavosurface angle on the cuspal incline Removal of the remaining lesion (i.e., caries lesion that extends
results in an 80-degree marginal amalgam angle. pulpally from the established pulpal loor) is best accomplished

A B C
• Fig. 10.36 Examples of more extensive Class I amalgam tooth preparation outline forms. A, Occlusal
outline form in the mandibular second premolar. B, Occlusolingual outline form in the maxillary irst molar.
C, Occlusofacial outline form in the mandibular irst molar.

A B
C
• Fig. 10.37 Removal of enamel issure extending over most of the pulpal loor. A, Full-length occlusal
issure remnant remaining on the pulpal loor after the initial tooth preparation. B and C, The pulpal loor
is deepened to a maximum depth of 2 mm to eliminate the issure or uncover dentin caries lesion.
 CHAPTER 10 Clinical Technique for Amalgam Retoration 329

A B
• Fig. 10.38 Removal of enamel pit and issure and dentin caries lesion that is limited to a few small
pit-and-issure remnants. A, Two pit remnants remain on the pulpal loor after the initial tooth preparation.
B, Carious enamel and dentin caries lesion have been removed.

13-7
-14

Peripheral
seat

Section of
peripheral
seat
A B C D
• Fig. 10.39 A and B, Removal of dentin caries lesion is accomplished with round burs (A) or spoon
excavators (B). C and D, The resistance form may be improved with a lat loor peripheral to the excavated
area(s).

using a discoid-type spoon excavator or a slowly revolving round for both. Amalgam is a brittle material with low edge strength
carbide bur of appropriate size (Fig. 10.39A and B). and tends to chip under occlusal stress if its angle at the margins
he removal of carious dentin will not afect the resistance form is less than 80 degrees. he transition between the external and
of the tooth because the periphery would not need further extension. internal walls should be gently rounded.93 he preparation should
In addition, it will not afect the resistance form of the restoration then be cleaned, carefully inspected as indicated previously in
as it will rest on the pulpal wall peripheral to the excavated area General Concepts Guiding Preparation for Amalgam Restorations,
or areas. he peripheral pulpal loor should be at the previously and any inal modiications completed.
described initial pulpal loor depth just inside the DEJ (see Fig.
10.39C and D). Usually, no secondary resistance or retention form Other Class I Amalgam Preparations
features are necessary Class I amalgam preparations. Class I preparations, especially those in esthetically important areas,
External walls may already have been inished during initial may be restored with composite because of their small size and
preparation steps; however, operator assessment of the external the maximal thickness of enamel available for bonding. However,
walls of the preparation is accomplished at this point, and any the following preparations may also be restored with
additional inish is accomplished as described previously and in amalgam:
Chapter 4. An occlusal cavosurface bevel is contraindicated in the 1. Facial pit of the mandibular molar.
tooth preparation for an amalgam restoration.92 It is important to 2. Lingual pit of the maxillary lateral incisor.
provide an approximate 90- to 100-degree cavosurface angle, which 3. Occlusal pits of the mandibular irst premolar.
should result in 80- to 90-degree amalgam at the margins.92 his 4. Occlusal pits and issures of the maxillary irst molar.
butt-joint marginal area (which approximates 90-degree cavosurface 5. Occlusal pits and fissures of the mandibular second
marginal angles for both enamel and amalgam) allows strength premolar.
330 C HA P T E R 1 0 Clinical Technique for Amalgam Retoration

A B C
• Fig. 10.40 Mandibular molar. A, Facial pit with a caries lesion. B, The bur positioned perpendicular
to the tooth surface for entry. C, Outline of restoration.

the cavosurface margins are completely covered with well-condensed

amalgam. Final condensation over cavosurface margins should be
done perpendicular to the external enamel surface adjacent to the
margins. The overpacked amalgam should then be precarve
burnished.

Finishing and Polishing of the Amalgam

With care, carving may begin immediately after condensation.
Sharp discoid-cleoid carvers of suitable sizes are useful for this.
he larger end of the discoid-cleoid instrument (No. 3/6) is used
irst, followed by the smaller instrument (No. 4/5) in regions not
accessible to the larger instrument. Alternatively, the Hollenback
• Fig. 10.41 Carious lingual pit and issure and restoration on the maxil-
carver may be used, with care not to overcarve the groove or fossa
lary lateral incisor.
areas. All carving should be done with the edge of the blade
perpendicular to the margins as the instrument is moved parallel
Examples of some of these types of preparations and restorations to the margins. Part of the edge of the carving blade should rest
are provided in Figs. 10.40, 10.41, 10.42, 10.43, 10.44, and 10.45. on the unprepared tooth surface adjacent to the preparation margin
(see Fig. 10.47F). Using this surface as a guide helps prevent
Retorative Technique for Cla I Amalgam overcarving amalgam at the margins and produces a continuity of
surface contour across the preparation margins. During carving,
Preparation thin amalgam should be removed from areas of enameloplasty.
Desensitizer Placement hin amalgam left in these areas may fracture because of its low
edge strength. Deep occlusal anatomy should not be carved into
A dentin desensitizer is placed in the preparation according to the restoration because these may thin the amalgam at the margins
manufacturer recommendations before amalgam condensation and weaken the restoration (see Fig. 10.47G). Undercarving leaves
(Fig. 10.46).72 thin portions of amalgam (subject to fracture) on the unprepared
tooth surface. he thin portion of amalgam extending beyond the
Matrix Placement margin is referred to as lash. he mesial and distal fossae should
Generally matrices are unnecessary for a conservative Class I be carved slightly deeper than the proximal marginal ridges (see
amalgam restoration except as speciied in later sections. Fig. 10.47H).
After carving is completed, the outline of the amalgam margin
Insertion and Carving of the Amalgam should relect the contour and location of the prepared cavosurface
he triturated amalgam (Fig. 10.47A) is placed into an amalgam margin, revealing a regular (i.e., not ragged) outline with gentle
well. he outline of the tooth preparation should be reviewed curves. An amalgam outline that is larger or irregular is undercarved
before inserting amalgam to establish a mental image that will and requires further carving or inishing (Fig. 10.48). An amalgam
later aid in carving amalgam to the cavosurface margin. Preoperative restoration that is more than minimally overcarved (i.e., a sub-
occlusal contact locations should be recalled (see Fig. 10.47B). marginal defect >0.2 mm) should be replaced.94 If the total carving
Amalgam should be carefully condensed into the pulpal line angles time is short enough, the smoothness of the carved surface may
(see Fig. 10.47C). he preparation should be overpacked 1 mm be improved by wiping with a small, damp ball of cotton held
or more using heavy pressure (see Fig. 10.47D). his ensures that with the cotton pliers. Alternatively, postcarve burnishing may be
 CHAPTER 10 Clinical Technique for Amalgam Retoration 331

A B
• Fig. 10.42 Maxillary lateral incisor. A, Preoperative radiograph of dens in dente. B, Radiograph of
restoration after 13 years. (Courtesy Dr. Ludwig Scott.)

L
B
D
A

90
E
C

C B A I

• Fig. 10.43 A, Preparation design and restoration of carious occlusal pits on the mandibular irst
premolar. B, Bur tilt for entry. The cutting instrument is held such that its long axis (broken line, CI) is
parallel with the bisector (B) of the angle formed by the long axis of the tooth (LA) and the line (P) that
is perpendicular to the plane (DE) drawn through the facial and lingual cusp points. This dotted line
(CI) is the bur position for entry. C, Conventional outline, including occlusal pits and central issure.

A B C
• Fig. 10.44 Maxillary irst molar. A, Outline necessary to include the carious mesial and central pits
connected by the issure. B, Preparation outline extended from outline in A to include distal pit and con-
necting deep issure in oblique ridge. C, Preparation outline extended from outline in B to include distal
oblique and lingual issures.
332 C HA P T E R 1 0 Clinical Technique for Amalgam Retoration

issure and distal pit on the occlusal surface (Fig. 10.49). Composite
may also be used as the restorative material in smaller lesions.
After local anesthesia and evaluation of the occlusal contacts,
the use of a rubber dam is generally recommended for isolation
of the operating ield. Alternatively, typical Class I preparations
may be adequately isolated with cotton rolls.

Tooth Preparation
he initial tooth preparation involves the establishment of the
A B outline, primary resistance, and primary retention forms, as well
as initial preparation depth. he accepted principles of the outline
• Fig. 10.45 Mandibular second premolar. A, Typical occlusal outline. form (previously presented) should be observed with special attention
B, Extension through the lingual ridge enamel is necessary when enamelo- to the following:
plasty does not eliminate the lingual issure. 1. he tooth preparation should be no wider than necessary; ideally,
the mesiodistal width of the lingual extension should not exceed
1 mm except for extension necessary to remove carious or
undermined enamel or to include unusual issuring.
2. When indicated, the tooth preparation should be more at the
expense of the oblique ridge, rather than centering over the
issure (weakening the small distolingual cusp).
3. Especially on smaller teeth, the occlusal portion may have a
slight distal tilt to conserve the dentin support of the distal
marginal ridge (Fig. 10.50).
4. he margins should extend as little as possible onto the oblique
ridge, distolingual cusp, and distal marginal ridge.
hese objectives help conserve the dentinal support (i.e., strength
of the tooth) and aid in establishing an enamel cavosurface angle
as close to 90 degrees as possible (Fig. 10.51). hey also help to
minimize deterioration of the restoration margins by locating the
margins away from enamel eminences where occlusal forces may
be concentrated.
he distal pit is identiied with indirect vision and entered with
• Fig. 10.46 Use of microbrush to apply the dentin desensitizer in the the end of the No. 245 bur (Fig. 10.52A). he long axis of the
tooth preparation. (Courtesy Aldridge D. Wilder, DDS.) bur usually should be parallel to the long axis of the tooth crown.
he dentinal support and strength of the distal marginal ridge and
the distolingual cusp should be conserved by positioning the bur
utilized to reine the anatomy and leave a smooth, satin inish. All such that it cuts more of the tooth structure mesial to the pit
shavings from the carving procedure should be removed from the rather than distal to the pit (e.g., 70 : 30 rather than 50 : 50), if
mouth with the aid of the oral evacuator. needed. he initial cut is to the level of the DEJ (a depth of
he occlusion on the restoration is then evaluated and adjusted 1.5–2 mm) (see Fig. 10.52B). At this depth, the pulpal loor is
so that all markings on the restoration and adjacent teeth are usually in dentin. When the entry cut is made (see Fig. 10.52C),
uniform (see Fig. 10.23). the bur (maintaining the initial established depth) is moved to
Extensive caries lesions require a more extensive restoration include any remaining issures facial to the point of entry (see Fig.
(which is a clear indication for amalgam as compared with composite 10.52D). he bur is then moved along the issure toward the
resin). Use of amalgam in large Class I restorations provides good lingual surface (see Fig. 10.52E). As with Class I occlusal prepara-
wear resistance and stable occlusal contact relationships. For very tions, a slight distal inclination of the bur is indicated occasionally
large Class I restorations, a bonding system may be used, although (particularly in smaller teeth) to conserve the dentinal support
this book does not promote such use. he perceived beneits of and strength of the marginal ridge and the distolingual cusp. To
bonded amalgams have not been substantiated. 85,95-99 Bonded ensure adequate strength for the marginal ridge, the distopulpal
amalgams have no advantage as compared with the conventional line angle should not approach the distal surface of the tooth closer
technique described above. Carving the extensive Class I restoration than 2 mm. On large molars, the bur position should remain
is often more complex because more cuspal inclines are included parallel to the long axis of the tooth, particularly if the bur is ofset
in the preparation. Appropriate contours, occlusal contacts, and slightly mesial to the center of the issure. Keeping the bur parallel
groove/fossa anatomy must be provided. Finishing and polishing to the long axis of the tooth creates a distal wall with slight occlusal
indications and techniques are as described previously. convergence, providing favorable enamel and amalgam angles. he
bur is moved lingually along the issure, maintaining a uniform
depth until the preparation is extended onto the lingual surface
Tooth Preparation for Cla I Occluolingual and (see Fig. 10.52F). he pulpal loor should follow the contour of
Occluofacial Amalgam Retoration the occlusal surface and the DEJ, which usually rises occlusally as
the bur moves lingually.
Occlusolingual amalgam restorations may be used on maxillary he mesial and distal walls of the occlusal portion of the
molars when a lingual issure connects with the distal oblique preparation should converge occlusally because of the shape of the
 CHAPTER 10 Clinical Technique for Amalgam Retoration 333

A B

D E F

G H
• Fig. 10.47 Restoration of occlusal tooth preparation. A, Properly triturated amalgam is a homoge-
neous mass with slightly relective surface. A properly mixed mass will latten slightly if dropped on a
tabletop. B, The operator should have a mental image of the outline form of the preparation before
condensing amalgam to aid in locating the cavosurface margins during the carving procedure.
C, Amalgam should be inserted incrementally and condensed with overlapping strokes. D and E, The
tooth preparation should be overpacked to ensure well-condensed marginal amalgam that is not mercury
rich. F, The carver should rest partially on the external tooth surface adjacent to the margins to prevent
overcarving. G, Deep occlusal grooves invite chipping of amalgam at the margins. Thin portions of
amalgam left on the external surfaces soon break away, giving the appearance that amalgam has grown
out of the preparation. H, Carve fossae slightly deeper than the proximal marginal ridges. (A, From Darby
ML, Walsh MM: Dental hygiene: theory and practice, ed 3, St. Louis, Saunders, 2010. B, D, and E,
Courtesy Aldridge D. Wilder, DDS.)

bur. If the slight distal bur tilt was required, the mesial and distal he lingual portion is prepared at this point by using one of
walls still should converge relative to each other (although the two techniques. In one technique, the lingual surface is prepared
distal wall may be divergent occlusally, relative to the tooth’s long with the bur’s long axis parallel with the lingual surface (Fig. 10.53A
axis). Convergence of the mesial and distal walls ensures occlusal and B). he tip of the bur should be located at the gingival extent
retention form is adequate. of the lingual issure. he bur should be controlled so that it does
334 C HA P T E R 1 0 Clinical Technique for Amalgam Retoration

A B
• Fig. 10.48 A, Undercarved amalgam with lash beyond the margins. The restoration outline is irregular
and larger than the preparation outline in Fig. 10.36B. B, Correctly carved amalgam restoration. (Courtesy
Aldridge D. Wilder, DDS.)

100°
90°

• Fig. 10.51 Enamel cavosurface angles of 90 to 100 degrees are ideal.

afecting the lingual surface is wide mesiodistally, the resultant

• Fig. 10.49 Outline of margins for occlusolingual tooth preparation. mesial and distal external walls may diverge to the lingual. In this
case the amalgam will require retention grooves to prevent lingual
displacement. An axial depth of 0.5 mm inside the DEJ is indicated
if retentive grooves are required. A second, alternate approach to
preparing the lingual aspect of the preparation may also be con-
sidered. In this case, the No. 245 bur is held perpendicular to the
cusp ridge and then the lingual surface, as it extends the preparation
from the occlusal surface gingivally (to include the entire defect).
his technique also results in opposing preparation walls that
converge lingually.
he No. 245 bur may be used with its long axis perpendicular
to the axial wall to accentuate (i.e., reine) the mesioaxial and
distoaxial line angles; this also results in the mesial and distal walls
converging lingually because of the shape of the bur (see Fig.
10.53D and E). During this step, the axial wall depth is not altered
(see Fig. 10.53F). he occlusal and lingual convergences usually
• Fig. 10.50 Small distal inclination of the bur on smaller teeth may be
indicated to conserve the dentinal support and the strength of the marginal
provide a suicient preparation retention form, and retention
ridge. grooves are not needed.
he axiopulpal line angle must be rounded to limit the areas
of stress concentration and ensure adequate preparation depth and
not “roll out” onto the lingual surface, which may “round over” amalgam thickness (Fig. 10.54). Initial tooth preparation of the
or damage the cavosurface margin. he facial inclination of the occlusolingual preparation is now complete. As mentioned previ-
bur must be altered as the cutting progresses to establish the axial ously, enameloplasty may be performed to conserve the tooth
wall of the lingual portion at a uniform depth of 0.5 mm inside structure and limit extension.
the DEJ (see Fig. 10.53C). he axial wall should follow the contour Additional retention in the lingual extension may be required
of the lingual surface of the tooth with an axial depth of 0.2 mm if the extension is wide mesiodistally or if it was prepared without
inside the DEJ at the preparation periphery. When the caries lesion a lingual convergence. If additional retention is required, the No.
A B C

D E F
• Fig. 10.52 Occlusolingual tooth preparation. A, No. 245 bur positioned for entry. B, Penetration to a
minimal depth of 1.5 to 2 mm. C, Entry cut. D, The remaining issures facial to the point of entry are
removed with the same bur. E and F, A cut lingually along the issure until the bur has extended the
preparation onto the lingual surface.

245

A B C

D E F
• Fig. 10.53 Occlusolingual tooth preparation. A, Position of bur to cut the lingual portion. B, Initial entry
of the bur for cutting the lingual portion. C, The inclination of the bur is altered to establish the correct
axial wall depth. D and E, The bur is directed perpendicular to the axial wall to accentuate the mesioaxial
and distoaxial line angles. F, The axial wall depth should be 0.2 to 0.5 mm inside the DEJ.

A B
• Fig. 10.54 A, Bur position for rounding the axiopulpal line angle. B, Axiopulpal line angle rounded.
336 C HA P T E R 1 0 Clinical Technique for Amalgam Retoration

A B

C D
• Fig. 10.55 Secondary retention form. A, Bur position for preparing groove in mesioaxial line angle.
B, Completed groove is internal to the DEJ. C, Bur position for the retention cove in the faciopulpal line
angle. D, Completed cove is internal to the DEJ.

A B
• Fig. 10.56 A, Any remaining pit and issure in enamel and soft dentin on established pulpal and axial
walls are removed. B, Completed tooth preparation.

4 or No. 169 bur may be used to prepare grooves into the mesioaxial prepare this cove. Care should be taken so as not to undermine
1

and distoaxial line angles (Fig. 10.55A). If these angles are in enamel, the occlusal enamel. his retentive cove is recommended only if
the axial wall must be deepened to 0.5 mm axially of the DEJ to occlusal convergence of the mesial and distal walls of the occlusal
allow the grooves to be prepared in dentin and to not undermine portion is absent or inadequate.
enamel. he depth of the grooves at the gingival loor is one half he inal tooth preparation is accomplished by removal of the
the diameter of the No. 1 4 bur. he cutting direction for each groove remaining caries lesion on the pulpal and axial walls (Fig. 10.56)
is the bisector of the respective line angle. he grooves are prepared with an appropriate round bur, a discoid-type spoon excavator, or
in the mesioaxial and distoaxial line angles of the ideally positioned both. A RMGI is placed in areas of deep caries removal for pulpal
axial wall and 0.2 mm axial to the DEJ. he grooves should diminish protection. he external walls are inished. Any irregularities at
in depth toward the occlusal surface, terminating midway along the margins may indicate weak enamel that may be removed by
the axial wall (see Fig. 10.55B). he adequacy of the groove should the side of the No. 245 bur rotating at low speed. he preparation
be tested by inserting the tine of an explorer into the groove and should then be cleaned, carefully inspected as indicated in General
detecting resistance to lingual movement. he depth of the groove Concepts Guiding Preparation for Amalgam Restorations, and
should prevent the explorer from being withdrawn lingually. (See any inal modiications completed.
Secondary Resistance and Retention Forms for a description of
placing retentive grooves in the proximal boxes of Class II amalgam
preparations; the techniques are similar.) Retorative Technique for Cla I Occluolingual
Extension of a facial occlusal issure may have required a slight or Occluofacial Amalgam Preparation
divergence occlusally to the facial wall to conserve support of the
facial ridge. If so, and if deemed necessary, the No. 1 4 round bur Desensitizer Placement
may be used to prepare a retention cove in the faciopulpal line A dentin desensitizer is placed over the prepared tooth structure
angle (see Fig. 10.55C and D). he tip of the No. 245 bur held and rinsed per manufacturer instructions. Excess moisture is removed
parallel to the long axis of the tooth crown also might be used to using air stream without desiccating the dentin.
 CHAPTER 10 Clinical Technique for Amalgam Retoration 337

lingual portion of the tooth preparation. If so, a piece of stainless

Matrix Placement (If Necessary) steel matrix material (0.05 mm thick and 8 mm wide) is cut to
Using a matrix to support the lingual portion of the restoration it between the lingual surface of the tooth and the band already
during condensation is occasionally necessary. A matrix is helpful in place (see Fig. 10.57B). he gingival edge of this segment of
to prevent “land sliding” during condensation and to ensure marginal matrix material is placed slightly gingival to the gingival edge of
adaptation and strength of the restoration. he Tolemire matrix the band to help secure the band segment. A quick-setting, rigid
retainer is used to secure a matrix band to the tooth (as described polyvinyl siloxane (PVS)–based material may be used between the
later). Because this type of matrix band does not intimately adapt sectional matrix and the Tolemire matrix band, to prevent lingual
to the lingual groove area of the tooth (Fig. 10.57A), an additional displacement of the sectional matrix during condensation of the
step may be necessary to provide a matrix that is rigid on the amalgam. Alternatively, green stick compound may be used. In

A B C

Matrix strip
Tofflemire
retainer

Tooth
preparation Wedge
D E F

G H
• Fig. 10.57 Matrix for occlusolingual tooth preparation. A, Matrix band secured to the tooth with
Toflemire retainer. B, Positioning a small strip of stainless steel matrix material between the tooth and the
band already in place. C, Inserting the wedge and the rigid supporting material. D, Compressing the rigid
supporting material gingivally (or holding the steel strip in correct position while the material sets), which
adapts the steel strip to the lingual surface. E, Cross section of the tooth preparation and the matrix
construction. F, Using the explorer to remove excess amalgam adjacent to the lingual matrix. G, Carving
completed. H, Polished restoration.
338 C HA P T E R 1 0 Clinical Technique for Amalgam Retoration

this case, the end of a toothpick wedge is covered with softened

(heated) compound. he compound-coated wedge is then imme- Clinical Technique for Cla II
diately inserted between the Tolemire band and the cut piece of Amalgam Retoration
matrix material (see Fig. 10.57C). While the compound is still
soft, a suitable burnisher is used to press the compound gingivally, Class II restorations restore defects that afect one or both of the
securing the matrix tightly against the gingival cavosurface margin proximal surfaces of posterior teeth (see Fig. 10.26B). Amalgam
and the lingual surface of the tooth to provide a rigid, lingual restorations that restore one or both of the proximal surfaces of
matrix (see Fig. 10.57D and E). his matrix for the occlusolingual the tooth may provide years of service to the patient when (1) the
amalgam restoration is referred to as the Barton matrix. Occasionally operating ield is isolated, (2) the tooth preparation is correct, (3)
the piece of strip matrix may be positioned appropriately by using the matrix is suitable, and (4) the restorative material is manipulated
only the wedge (without the rigid PVS or compound properly. Application of the principles discussed here will result
support). in high-quality, durable Class II amalgam restorations.

Insertion of the Amalgam Initial Clinical Procedures

Insertion of amalgam is accomplished as previously described Occlusal contacts should be marked with articulating paper before
in General Concepts Guiding Restoration with Amalgam and tooth preparation. A mental image of these contacts will serve as
for the Class I occlusal tooth preparation. Condensation is begun a guide in tooth preparation and restoration. Any opposing “plung-
at the gingival wall at the lingual component of the preparation. ing cusp” (that is not aligned well with the occlusal plane) or other
If a matrix is not used, care must be taken to ensure that “land sharply pointed cusp may need to be recontoured to reduce the
sliding” of the amalgam does not occur because two adjoining risk of fracture of the new restoration. Before tooth preparation
surfaces of the tooth are being restored. For this technique, the for amalgam, the placement of a rubber dam is generally recom-
last increments of amalgam may be condensed on the lingual mended. It is especially beneicial when the caries lesion is extensive.
surface with the side of a large condenser. Its long, broadly If an existing defective restoration has rough proximal contacts,
rounded contour approximates the rectangular shape of the the restoration may be removed before rubber dam application.
lingual groove preparation. Appropriate care should be taken Soft dentin should be removed with the rubber dam in place,
(when condensing the occlusal surface) to prevent fracturing the especially if pulpal exposure is a possibility. Insertion of an inter-
lingual amalgam. Another technique is to have the assistant secure proximal wedge or wedges is useful to depress and protect the
the condensed lingual surface with a broad condenser nib, while rubber dam and underlying soft tissue, separate teeth slightly, and
the operator completes the condensation of the occlusal surface. may serve as a guide to prevent gingival overextension of the
Regardless of the technique used, the amalgam must be well proximal boxes.
condensed.

Contouring and Finishing of the Amalgam Restoration Tooth Preparation for Cla II Amalgam
When the preparation is suiciently overilled, carving of the Retoration That Involve Only One Proximal
occlusal surface may begin immediately with a sharp discoid-cleoid
instrument or a Hollenback carver. All carving should be done
Surface
with the edge of the blade perpendicular to the margin and the his section introduces the principles and techniques of a Class
blade moving parallel to the margin. To prevent overcarving, the II tooth preparation for an amalgam restoration involving a caries
blade edge should be guided by the unprepared tooth surface lesion on one proximal surface. A small, conservative mesiocclusal
adjacent to the margin. An explorer is used to remove excess tooth preparation on the mandibular second premolar is presented
amalgam adjacent to the lingual matrix before matrix removal to illustrate basic concepts. Composite may also be an acceptable
(see Fig. 10.57F). After the occlusal carving is complete, the restorative material for this preparation. Preoperative placement
Tolemire retainer is loosened from the band, and the band is of a wedge (“pre-wedging”) in the space adjacent to the proximal
removed with No. 110 pliers. The free ends of the band are surface with the caries lesion will create space between the teeth.
pushed one at a time, lingually and occlusally, through the proximal his lowers the risk of iatrogenic damage to the adjacent tooth
contacts. After the lingual carving is complete (see Fig. 10.57G), during preparation.
the rubber dam is removed and the restoration is adjusted to
ensure proper occlusion. Most amalgams do not require inishing Initial Tooth Preparation
and polishing. Fig. 10.57H illustrates a polished occlusolingual
restoration. Occlusal Outline Form (Occlusal Step)
he occlusal outline form of a Class II tooth preparation for
Class I Occlusofacial Amalgam Restorations amalgam is similar to that for a Class I tooth preparation. Using
Occasionally, mandibular molars exhibit issures that extend from high speed with air-water spray, the operator enters the pit nearest
the occlusal surface through the facial cusp ridge and onto the the involved proximal surface with a punch cut using a No. 245
facial surface. he preparation and restoration of these defects bur oriented as illustrated in Fig. 10.59A and B. he bur should
are very similar to those described for Class I occlusolingual be rotating when it is applied to the tooth and should not stop
amalgam restorations. Although these may be restored with rotating until removed. Viewed from the proximal and lingual
composite, an illustration of preparation and restoration with (facial) aspects, the long axis of the bur and the long axis of the
amalgam is provided in Fig. 10.58. he amalgam restoration tooth crown should remain parallel during the cutting procedures.
may be polished after it is completely set. he shape of abrasive he dentin caries lesion initially spreads at the DEJ; therefore the
points may need to be modiied to allow optimal polishing (see goal of the initial cut is to reach the DEJ. he DEJ location in
Fig. 10.58I and J). posterior teeth is approximately 1.5 to 2.0 mm from the occlusal
 CHAPTER 10 Clinical Technique for Amalgam Retoration 339

A B C

D E F

G H

I J

• Fig. 10.58 Fissure extension. A, Facial occlusal issure continuous with the issure on the facial
surface. B, Extension through the facial ridge onto the facial surface. C, Appearance of the tooth prepara-
tion after extension through the ridge. D, The facial surface portion of the extension is cut with the side
of the bur. E, The line angles are sharpened by directing the bur from the facial aspect. F, Sharpening the
line angles from the occlusal direction with a No. 169 L bur. G, Ensuring the retention form by preparing
retention grooves with a No. 14 round bur. H, Completed tooth preparation. I, The rubber polishing point
may be reshaped (blunted as indicated) on a coarse diamond wheel. J, Proper orientation of the rubber
point when polishing the facial surface groove area.

surface. As the bur enters the pit, a target depth of 0.1 to 0.2 mm opposite carious pit (see Fig. 10.59C and D). he isthmus width
into dentin (i.e., just into dentin) should be established. his depth should be as narrow as possible, preferably no wider than one
is one half to two thirds the length of the cutting portion of a No. quarter the intercuspal distance.54,55,100,101 Ideally the preparation
245 bur, or approximately 1.5 mm as measured from the central should be the width of the No. 245 bur. Narrow restorations
fissure and 2 mm from the preparation external wall. While provide a greater length of clinical service.57,60 Generally the amount
maintaining the same depth and bur orientation, the bur is moved of remaining tooth structure is more important to restoration
to extend the outline to include the carious central issure and the longevity than is the restorative material used.102 Ultimately, the
340 C HA P T E R 1 0 Clinical Technique for Amalgam Retoration

245

A B C

D E
• Fig. 10.59 Entry and occlusal step. A, Bur position for entry, as viewed proximally. Note the slight
lingual tilt of the bur. B, Bur position as viewed lingually. C, The tooth is entered with a punch cut, and
extension is done distally along central issure at a uniform depth of 1.5 to 2 mm (1.5 mm at issure;
because of the inclination of the unprepared tooth surface, the corresponding measurement on the pre-
pared wall is greater). D, Occlusal view of C. E, Completed occlusal step.

extension of the caries lesion at the DEJ will determine the amount extension of the central issure preparation that is not in a straight
of preparation extension and resultant width. he pulpal loor of direction from pit to pit (see Fig. 10.59E). A dovetail outline form
the preparation should follow the slight rise and fall of the DEJ in the distal pit is not required if radiating fissures are not
along the central issure in teeth with prominent triangular ridges. present.103,104 Enameloplasty should be performed, where indicated,
Maintaining the bur parallel to the long axis of the tooth crown to conserve the tooth structure.
creates facial, lingual, and distal walls with a slight occlusal con- Before extending into the involved proximal marginal ridge
vergence as well as external wall orientation favorable for amalgam (the mesial ridge, in this example), the inal locations of the facial
use. he facial, lingual, and distal walls should be extended until and lingual walls of the proximal box are estimated visually. Visual
a sound DEJ is reached. Proper extension will result in the formation assessment prevents overextension of the occlusal outline form
of the peripheral seat, which aids in the primary resistance form. (i.e., occlusal step) where it joins the proximal outline form (i.e.,
It may be necessary to tilt the bur to diverge occlusally at the distal proximal box). Fig. 10.60 illustrates visualization of the inal location
wall if further distal extension would undermine the marginal of the proximoocclusal margins before preparing the proximal box.
ridge of its dentinal support. During development of the distal Showing the view from the occlusal aspect, Fig. 10.61 illustrates
pit area of the preparation, extension to include any distofacial a reverse curve in the occlusal outline of a Class II preparation,
and distolingual developmental issures radiating from the pit may which often results when developing the mesiofacial wall perpen-
be indicated. he distal pit area (in this example) provides a dovetail dicular to the enamel rod direction while, at the same time, conserv-
retention form, which will prevent mesial displacement of the ing as much of the facial cusp structure as possible.101 he extension
completed Class II restoration. However, the dovetail feature is into the mesiofacial cusp is limited to that amount required to
not required in the occlusal step of a single proximal surface permit a 90-degree mesiofacial margin. Lingually, the reverse curve
preparation unless a issure emanating from an occlusal pit indicates usually is minimal (if necessary at all) because of the relationship
it. his type of retention form (i.e., form that provides resistance of the central issure relative to the faciolingual position of the
to mesial displacement of the restoration) also is provided by any proximal contact.
 CHAPTER 10 Clinical Technique for Amalgam Retoration 341

10.62A). he end of the bur is allowed to cut a ditch gingivally

along the exposed proximal DEJ, two thirds at the expense of
enamel and one third at the expense of dentin. he 0.8-mm-diameter
bur end cuts approximately 0.5 to 0.6 mm into enamel and 0.2
to 0.3 mm into dentin. Pressure is directed gingivally and lightly
toward the mesial surface to keep the bur against the proximal
enamel, while the bur is moved facially and lingually along the
DEJ. he ditch is extended gingivally just beyond the caries lesion
or the proximal contact, whichever is greater (see Fig. 10.62B).
• Fig. 10.60 Visualize inal location of proximoocclusal margins (dotted Axial wall dentinal depths will vary based on the gingival extension
lines) before preparing the proximal box. of the preparation (see Fig. 10.62C). he axial wall follows the
faciolingual contour of the proximal surface and the DEJ (see Fig.
10.62D).
It is necessary to visualize the completed mesiofacial and
mesiolingual margins as right-angle projections of the facial and
lingual limits of the ditch to establish the proper faciolingual ditch
extension (see Fig. 10.62E). When preparing a tooth with a small
lesion, these margins may clear the adjacent tooth by only 0.2 to
0.3 mm.101 A guide for the gingival extension is the visualization
that the inished gingival margin will be only slightly gingival to
the gingival limit of the ditch. his gingival margin will likely
90° clear the adjacent tooth by only 0.5 mm when treating an early
cavitated proximal lesion (see Fig. 10.62F).103 Recall that the caries
lesion develops immediately gingival to the proximal contact and
therefore the preparation will always result in gingival clearance,
and that the amount of clearance will depend on the size of the
caries lesion. Clearance of the proximal margins (i.e., mesiofacial,
mesiolingual, gingival) greater than 0.5 mm is excessive, unless
indicated to include the caries lesion, undermined enamel, or
• Fig. 10.61 The reverse curve in the occlusal outline usually is created
existing restorative material. he location of the inal proximal
when the mesiofacial enamel wall is parallel to the enamel rod direction.
Lingually, the reverse curve is very slight, often unnecessary.
margins (i.e., facial, lingual, gingival) should be established with
hand instruments (i.e., chisels, hatchets, trimmers) and not the
No. 245 bur, so as to prevent unnecessary overextension (see Fig.
While maintaining the established pulpal depth and with the 10.62E). Extending gingival margins into the gingival sulcus should
bur parallel to the long axis of the tooth crown, the preparation be avoided, where possible, because subgingival margins are more
is extended mesially, stopping approximately 0.8 mm short of diicult to restore and may be a contributing factor to periodontal
cutting through the marginal ridge into the contact area. he disease.105-107
occlusal step in this region is made slightly wider faciolingually he depth of the axial dentinal wall should be adjusted to
than in the Class I preparation because additional width is necessary approximately 0.5 mm if retention grooves are deemed necessary
for the proximal box. he proper depth of the occlusal portion of (i.e., if caries lesion removal requires placement/orientation of
the preparation increases the strength of the restoration however, facial and lingual walls that are very divergent). his will allow
more than does faciolingual width (see Fig. 10.59C and E). Although the grooves to be prepared into the axiolingual and axiofacial line
this extension includes part of the mesial marginal ridge, it also angles without undermining the proximal wall enamel. If the
exposes the marginal ridge DEJ. he location of the DEJ is an proximal ditch cut is entirely in dentin, the initial axial wall is too
important guide in the development of the proximal deep. Because the proximal enamel becomes thinner from the
preparation. occlusal to the gingival aspect, the end of the bur comes closer to
the external tooth surface as the cutting progresses gingivally (see
Proximal Outline Form (the Proximal “Box”) Fig. 10.62B, C, and I). Premolars may have proximal boxes that
Before initiating the proximal outline form (i.e., the proximal are shallower pulpally than are molars because premolars typically
“box”), the operator should visualize the desired inal location of have thinner enamel. In the tooth crown, the ideal dentinal depth
the facial and lingual walls relative to the contact. he objectives of the axial wall of the proximal boxes of premolars and molars
for the extension of the proximal margins are to (1) include all should be the same (two thirds to three fourths the diameter of
caries lesion, defects, or existing restorative material; (2) create the No. 245 bur [or 0.5–0.6 mm]).101 When the extension places
approximately 90-degree cavosurface margins (i.e., butt-joint the gingival margin in cementum, the initial pulpal depth of the
margins); and (3) establish (ideally) not more than 0.5-mm clearance axiogingival line angle should be 0.7 to 0.8 mm (the diameter of
with the adjacent proximal surface facially, lingually, and the tip end of the No. 245 bur is 0.8 mm). he bur may shave
gingivally. the side of the wedge that is protecting the rubber dam and the
he initial procedure in preparing the outline form of the underlying gingiva (see Fig. 10.62C).
proximal box is the isolation of the proximal (i.e., in this case, he gingival extension of the proximal ditch may be measured
mesial) enamel by the proximal ditch cut. While maintaining the by irst noting the depth of the nonrotating bur in the ditch. he
same orientation of the bur, it is positioned over the DEJ in the dentist removes the bur from the preparation and holds it in the
pulpal loor next to the remaining mesial marginal ridge (Fig. facial embrasure at the same level to observe the relationship of
342 C HA P T E R 1 0 Clinical Technique for Amalgam Retoration

Axial wall
dentinal depths:
crown, 0.5-0.6 mm
root, 0.75-0.8 mm a
b

c
0.5 mm
A B
C
Facial

Bur

Remaining 1/ "
4
spurs of
enamel

Bur

D E Lingual F

G H I
• Fig. 10.62 Isolation of proximal enamel. A, Bur position to begin the proximal ditch cut. B, The proxi-
mal ditch is extended gingivally to the desired level of the gingival wall (i.e., loor). C, Variance in the pulpal
depth of the axiogingival line angle as the extension of the gingival wall varies: (a) at minimal gingival
extension; (b) at moderate extension; (c) at extension that places gingival margin in cementum, whereupon
the pulpal depth is 0.75 to 0.8 mm and the bur may shave the side of wedge. D, The proximal ditch cut
results in the axial wall that follows the outside contour of the proximal surface. E, The position of the
proximal walls (i.e., facial, lingual, gingival) should not be overextended with the No. 245 bur, considering
additional extension will occur when the remaining spurs of enamel are removed. F, When a small lesion
is prepared, the gingival margin should clear the adjacent tooth by only 0.5 mm. This clearance may be
measured with the side of the explorer. The diameter of the tine of a No. 23 explorer is ~0.5 mm at 6 mm
from its tip. G, The faciolingual dimension of the proximal ditch is greater at the gingival level than at the
occlusal level to provide occlusal convergence of the facial and lingual proximal box walls. H, To isolate
and weaken the proximal enamel further, the bur is moved toward and perpendicular to the proximal
surface. I, The side of the bur may emerge slightly through the proximal surface at the level of the gingival
loor (arrow).
 CHAPTER 10 Clinical Technique for Amalgam Retoration 343

A B C
• Fig. 10.63 Removing isolated enamel. A, Using a spoon excavator to fracture the weakened proximal
enamel. B, Occlusal view with the proximal enamel removed. C, Proximal view with the proximal enamel
removed.

the end of the bur to the proximal contact. A periodontal probe

also may be used.
he proximal ditch cut may diverge gingivally (i.e., converge
occlusally) to ensure that the faciolingual dimension at the gingival
aspect is greater than at the occlusal aspect (see Fig. 10.62G). he
shape of the No. 245 bur will provide this divergence. he gingival
divergence contributes to the retention form and provides for the
desirable extension of the facial and lingual proximal margins to
include defective tooth structure or old restorative material at the
gingival level, while conserving the marginal ridge and providing
for 90-degree amalgam at the margins on this ridge.55
Occasionally it is permissible not to extend the outline of the A B
proximal box facially or lingually beyond the proximal contact to
conserve the tooth structure.103 An example of this modiication • Fig. 10.64 Wedging. A, A round toothpick wedge placed in the gin-
is a narrow proximal lesion where broad proximal contact is present gival embrasure protects the gingiva and the rubber dam during prepara-
in a patient with low risk for caries. If it is necessary to extend tion of the proximal box. B, A triangular wedge is indicated when a deep
1 mm or more just to arbitrarily create clearance (i.e., to “break gingival extension of the proximal box is anticipated because the wedge’s
the contact”), the proximal margin is left in contact with the greatest cross-sectional dimension is at its base. Consequently it more
adjacent proximal surface. It is usually the facial margins that readily engages the remaining clinical tooth surface. Wedging increases
remain in contact as proximal caries lesions tend to develop slightly the interproximal space and limits the potential for iatrogenic damage of
adjacent tooth (or restoration) surfaces.
more toward the lingual.
he proximal extensions are completed when two cuts, one
starting at the facial limit of the proximal ditch and the other
starting at the lingual limit, extending toward and perpendicular will rapidly cut through any matrix material and damage the adjacent
to the proximal surface (until the bur is nearly through enamel at proximal surface. he isolated enamel, if still in place, may be
the contact level), are made (see Fig. 10.62H). he side of the bur fractured with a spoon excavator (Fig. 10.63) or by mesial movement
may emerge slightly through the surface at the level of the gingival with the side of the nonrotating bur.
loor (see Fig. 10.62I); this weakens the remaining enamel by To protect the gingiva and the rubber dam when extending
which the isolated portion is held. If this level is judged to be the gingival wall apically, a wooden wedge should already be in
insuiciently gingival, additional gingival extension should be place in the gingival embrasure to depress soft tissue and the rubber
accomplished using the isolated proximal enamel, that is still in dam.55 A round toothpick wedge is preferred unless a deep gingival
place, as a mental barrier to help the operator guide the bur. extension is anticipated (Fig. 10.64A). A triangular (i.e., anatomic)
Ensuring the presence of the proximal enamel surface helps to wedge is more appropriate for deep gingival extensions because
limit the likelihood of iatrogenically damaging the proximal surface the greatest cross-sectional dimension of the wedge is at its base;
of the adjacent tooth. At this stage, however, the remaining wall as the gingival wall is cut, the bur’s end corner may shave the
of enamel often breaks away during cutting, especially when high wedge slightly (see Fig. 10.64B). With a sharp enamel hatchet
speed is used. At such times, if additional use of the bur is indicated, (10-7-14), bin-angle chisel (12-7-8), or both, the dentist cleaves
a matrix band may be used around the adjacent tooth to limit away any remaining undermined proximal enamel (Fig. 10.65),
potential marring of its proximal surface; however, the relative establishing the proper orientation of the mesiolingual and mesio-
amount of protection aforded by the metal matrix material is very facial walls. Proximal walls that result in cavosurface angles of 90
limited and serves more as a visual guide than an actual physical degrees are desired.55 Cavosurface angles of 90 degrees ensure that
barrier. A No. 245 bur, rotating between 200,000 and 400,000 rpm, no undermined enamel rods remain on the proximal margins and
344 C HA P T E R 1 0 Clinical Technique for Amalgam Retoration

A B C
• Fig. 10.65 Removing the remaining undermined proximal enamel with an enamel hatchet on the facial
proximal wall (A), the lingual proximal wall (B), and the gingival wall (C).

A B C
• Fig. 10.66 Direction of mesiofacial and mesiolingual walls. A, Failure caused by a weak enamel margin.
B, Failure caused by a weak amalgam margin. C, Proper direction to the proximal walls results in full-
length enamel rods and 90-degree amalgam at the preparation margin. Retention grooves have been cut
0.2 mm inside the DEJ, and their direction of depth is parallel to the DEJ.

that the maximal edge strength of amalgam is maintained. he by using a rotary instrument, intermittent application of the bur
cutting edge of the instrument should not be aggressively forced along with air coolant alone (i.e., no water spray) is used to improve
against the gingival wall because this may cause a craze line (i.e., visualization and precision.
fracture) that extends gingivally in enamel, perhaps to the cervical he primary resistance form is provided by (1) the pulpal and
line. Fig. 10.66 shows the importance of the correct direction of gingival walls being relatively level (i.e., perpendicular to forces
the mesiofacial and mesiolingual walls, dictated by enamel rod directed along the long axis of the tooth); (2) restricting the exten-
direction and the physical properties of amalgam. If hand instru- sion of the walls to allow suicient dentin support to remain (and
ments were not used to remove the remaining spurs of enamel, therefore strong cusps and ridge areas) while at the same time
the proximal margins would have undermined enamel. To create establishing the peripheral seat; (3) restricting the occlusal outline
90-degree facial and lingual proximal margins with the No. 245 form (where possible) to areas receiving minimal occlusal contact;57
bur, the proximal margins would have to be signiicantly overex- (4) use of a reverse curve to optimize the strength of the amalgam
tended for an otherwise conservative preparation. he weakened and tooth structure at the junction of the occlusal step and proximal
enamel along the gingival wall is removed by using the enamel box; (5) slight rounding of the internal line angles to reduce stress
hatchet in a scraping motion (see Fig. 10.65C). concentration in the tooth structure (automatically created by bur
When the isolation of the proximal enamel has been executed design except for the axiopulpal line angle); and (6) providing
properly, the proximal box may be completed easily with hand- enough thickness of the restorative material to prevent its lexure
cutting instruments. Otherwise more cutting with rotary instruments and resultant fracture from the forces of mastication. he primary
is indicated. When a rotary instrument is used in a proximal box retention form is provided by the occlusal convergence of the facial
after the proximal enamel is removed, there is increased risk that and lingual walls and by the dovetail design of the occlusal step,
the instrument may either mar the adjacent proximal surface or if present.
“crawl out” of the box into the gingiva or across the proximal After completing the initial tooth preparation, the adjacent
margins. he latter mishap produces a rounded cavosurface angle, proximal surface should be evaluated. An adjacent proximal restora-
which results in a weak amalgam margin of less than 90 degrees tion may require recontouring to reestablish the normal anatomic
if not corrected. he risk of this occurring is markedly reduced convex shape; this may be done with abrasive inishing strips,
when high-speed operation is used. When inishing enamel margins disks, inishing burs, or a combination of these. Any iatrogenic
 CHAPTER 10 Clinical Technique for Amalgam Retoration 345

damage that compromises the convex adjacent proximal surface should be taken as indicated in General Concepts Guiding Prepara-
should be corrected by recontouring or restoration. tion for Amalgam Restorations.
After completion of the minimal gingival extension (i.e., the
Final Tooth Preparation gingivoaxial line angle is in sound dentin), a remnant of the enamel
portion of a caries lesion may remain on the gingival loor (wall),
Removing enamel pit-and-issure remnants and soft dentin on the seen in the form of a decalciied (i.e., white, chalky) or faulty area
pulpal wall in Class II preparations is accomplished in the same bordering the margin (Fig. 10.69). his situation dictates further
manner as in the Class I preparation. Soft dentin is removed with extension of a part or all of the gingival loor to place it in sound
a slowly revolving round bur of appropriate size, a discoid-type tooth structure. Extension of the entire gingival wall to include a
spoon excavator, or both. In general, the caries lesion removal large caries lesion may place the gingival margin so deep that
should stop when a hard or irm feel, with an explorer or small proper matrix application and wedging become extremely diicult.
spoon excavator, is achieved; this often occurs before all of the Fig. 10.70A illustrates an outline form that extends gingivally in
stained or discolored dentin is removed. he exception to this is the central portion of the gingival wall to include a caries lesion
when using the selective caries removal protocol (see Chapter 2). that is deep gingivally, although leaving the facial and lingual
Removing enamel pit-and-issure remnants and carious dentin gingival corners at a more occlusal position. his partial extension
should not afect the resistance form. To achieve an enhanced of the gingival wall permits wedging of the matrix band where
resistance form, the occlusal step should have pulpal seats at the otherwise it may be diicult and damaging to soft tissue. In this
initial preparation depth, perpendicular to the long axis of the instance, the gingival wedge may not tightly support a small portion
tooth in sound tooth structure and peripheral to the excavated of the band. Special care must be exercised by placing small amounts
area (Fig. 10.67). Carious dentin in the axial wall is removed with of amalgam in this area irst and thoroughly condensing with light
appropriate round burs, spoon excavators, or both so as to conserve pressure. In addition, care is exercised in carving the restoration
as much tooth structure as possible (Fig. 10.68). in this area to remove any excess that may have extruded gingivally
Any remaining old restorative material (including base and during condensation.
liner) may be left if no evidence of a recurrent caries lesion exists, Fig. 10.70B illustrates removal of a caries lesion facially and
if its periphery is intact, and if the tooth has been asymptomatic gingivally beyond the conventional margin position. Such minor
(assuming the pulp is vital). his concept is particularly important variations from the ideal preparation form permit conservation of
if removal of all remaining restorative material may increase the healthy tooth structure. A partial extension of a facial or lingual
risk of pulpal exposure. Appropriate steps to protect the pulp wall is permissible if (1) the entire wall is not weakened, (2) the

A B C

• Fig. 10.67 Management of small- to moderate-sized caries lesion on the pulpal wall. A, Soft dentin
extending beyond the ideal pulpal wall position. B, Incorrect lowering of the pulpal wall to include soft
dentin. C, Correct extension facially and lingually beyond the soft dentin. Note the caries removal below
the ideal pulpal wall level and the facial and lingual seats at the ideal pulpal wall level.

A B C
• Fig. 10.68 Management of a moderate to extensive caries lesion. A and B, Soft dentin on the axial
wall does not call for the preparation of the whole axial wall toward the pulp (dotted lines). C, Soft dentin
extending pulpally from the ideal axial wall position is conservatively removed with a round bur.
346 C HA P T E R 1 0 Clinical Technique for Amalgam Retoration

extension remains accessible and visible, (3) suicient gingival seats

remain to support the restoration, and (4) a butt-joint it at the Proximal Retention Grooves
amalgam–enamel margin (90-degree amalgam angle and 90-degree To enhance the retention form of the proximal portion, proximal
cavosurface angle) is possible. grooves may be indicated to counter proximal displacement of the
Conserving as much tooth structure as possible by limiting the amalgam restoration.55,108-110 he use of retention grooves in proximal
extensions of external walls helps to provide secondary resistance boxes is controversial. It has been reported that proximal retention
by limiting the risk of future tooth fracture from oblique forces. grooves in the axiofacial and axiolingual line angles may increase
Ensuring that all internal line angles are rounded is necessary to the fracture resistance and signiicantly strengthen the isthmus of
limit areas of stress concentration in the remaining tooth structure a Class II amalgam restoration and that these grooves are signiicantly
and in the new restoration and improves secondary resistance of superior to the axiogingival grooves in increasing the restoration’s
both. Use of the gingival margin trimmer or a bur to round the fracture strength.111-114 Other investigators have suggested, however,
axiopulpal line angle (Fig. 10.71) helps to increase the bulk of that retention grooves located occlusal to the axiopulpal line angle
restorative material and decrease the stress concentration within provide more resistance than do conventional grooves.108 It also
the restorative material. has been reported that proximal retention grooves are unnecessary
he secondary retention forms for the occlusal and proximal in preparations that include dovetails, as part of the occlusal
portions of the preparation should be independent of each other. preparation, when high-copper amalgam is used.109,115 Evidence
he occlusal convergence of the facial and lingual walls provide a suggests that retentive grooves may not be needed in conservative,
suicient retention form to the occlusal portion of the tooth narrow proximal boxes.110 he use of retention grooves is recom-
preparation. mended in tooth preparations with extensive proximal boxes.
Generally the depth of the grooves should be approximately half
of the diameter of the tip of the No. 169 or No. 1 4 round bur
(i.e., ~0.25–0.5 mm). he depth of retention grooves in extensively
wide proximal boxes may need to be 0.5 mm or greater at the
gingival aspect.

• Fig. 10.69 Remnant of caries lesion bordering the enamel margin after
insuficient gingival extension. Such a lesion indicates extending part or all
of the gingival loor to place it in sound tooth structure. (Courtesy Dr.
C. L. Sockwell.) • Fig. 10.71 Rounding the axiopulpal line angle.

A B
• Fig. 10.70 A, Outline form that permits extension of the center portion of the gingival wall to facilitate
proper matrix construction and wedging in situations where the caries lesion extends deep gingivally.
B, Outline form that permits partial wall extension facially and gingivally to conserve the tooth structure.
 CHAPTER 10 Clinical Technique for Amalgam Retoration 347

Retention grooves are prepared with a No. 169 L or No. 1 4 the bur. he tilt dictates the occlusal height of the groove, given
round bur with air coolant only (to improve visualization) and a constant depth. When using the No. 1 4 bur to prepare the
reduced speed (to improve tactile “feel” and control). he bur is proximal groove, the rotating bur is carried into the axiolinguo-
placed in the properly positioned axiolingual line angle and directed gingival (or axiofaciogingival) point angle, then moved parallel to
(i.e., translated) to bisect the angle (Fig. 10.72) approximately the DEJ to the depth of ~0.25 to 0.5 mm. It is then drawn occlusally
parallel to the DEJ (Fig. 10.73). his positions the retention groove along the axiolingual (or axiofacial) line angle, allowing the groove
0.2 mm inside the DEJ, maintaining the enamel support. he bur to become shallower and to terminate at the axiolinguopulpal (or
is tilted to allow cutting to the depth of the diameter of the end axiofaciopulpal) point angle (or more occlusally if the line angles
of the bur (which is initially positioned at the axiolinguogingival are <2 mm in length) (see Fig. 10.72D and E).
point angle) and to permit the groove to diminish in depth occlus- Regardless of the method used in placing the grooves, extreme
ally. he facial groove in the axiofacial line angle is prepared in a care is necessary to prevent the removal of dentin that immediately
similar manner. When the axiofacial and axiolingual line angles supports the proximal enamel. In addition, it is essential that the
are less than 2 mm in length, the tilt of the bur is reduced slightly grooves are not prepared entirely in the axial wall (i.e., incorrect
so that the proximal grooves are extended occlusally to disappear translation [moving the bur only in an axial direction]) because
midway between the DEJ and the enamel margin (see Fig. 10.72B groove placement in this area will not afect any resistance to
and C). proximal displacement of the amalgam (i.e., will not increase
he four characteristics or determinants of proximal grooves retention) and will increase the risk of iatrogenic pulpal
are (1) position, (2) translation, (3) depth, and (4) occlusogingival involvement.
orientation (see Fig. 10.73). Position refers to the axiofacial and An improperly positioned axiofacial or axiolingual line angle
axiolingual line angles of initial tooth preparation (0.5 mm axial must not be used as a positional guide for the proximal groove.
to the DEJ). Translation refers to the direction of movement of If the axial line angle is too shallow, the groove may remove the
the axis of the bur. Depth refers to the extent of translation (i.e., necessary dentinal support of enamel. If the line angle is too deep,
depth of the retention groove). Occlusogingival orientation is preparation of the groove may result in exposure of the pulp.
considered when using the No. 169 L bur and refers to the tilt of Retention grooves, when used, always should be placed 0.2 mm inside

A B C

D E
• Fig. 10.72 Proximal retention grooves. A, Position of the No. 169 L bur to prepare the retention groove
as the bur is moved lingually and pulpally. B, Lingual groove. Note the dentin support of the proximal
enamel. C, Completed grooves. D, Grooves prepared with a No. 14 round bur. E, Completed grooves.
348 C HA P T E R 1 0 Clinical Technique for Amalgam Retoration

DEJ C
View

A B 169L

0.5 mm depth of translation of c

tip of 169L bur (0.5 mm diam.)
at gingival floor level

Groove is
0.2 mm
from DEJ
If groove is to fade out at
Translation E occlusal DEJ, (c), bur is tilted
DEJ
at start of cutting to clear
D direction (c) 0.5 mm
F
• Fig. 10.73 Four characteristics of retentive grooves. A, Occlusal view of the mesioocclusal preparation
before placement of the retention grooves. B, Proximal view of the mesioocclusal preparation. C and D,
Position, translation, and depth. E and F, Occlusogingival orientation.

the DEJ of the facial and lingual proximal walls regardless of the root), the gingival cavosurface coniguration is 90 degrees to the
depth of the axial wall and associated line angles. external surface of the root.55 A sharp distal gingival margin trimmer
(13-95-10-14, R and L) is similarly used for distal proximal
Proximal Walls preparations. Alternatively, the side of an explorer tine may be
he preparation walls and margins should not have unsupported used to remove any friable enamel at the gingival margin. he tine
enamel and marginal irregularities.116 No occlusal cavosurface bevel is placed in the gingival embrasure apical to the gingival margin.
is indicated in the tooth preparation for amalgam. Ideally, a With some pressure against the prepared tooth, the tine is moved
90-degree cavosurface angle (maximum of 100 degrees) should be occlusally across the gingival margin to “trim” the margin of friable,
present at the proximal margin. he occlusal line angle may be unsupported enamel.
90 to 100 degrees. his angle aids in obtaining a marginal amalgam
angle of 90 degrees (≥80 degrees). Clinical experience has established Variation of Proximal Surface Tooth
that this “butt-joint” relationship of enamel and amalgam creates
the strongest margin.55 Amalgam is a brittle material and may Preparation
fracture under occlusal load if its angle at the margin is less than
80 degrees. his section describes variations in tooth preparation for some
A sharp mesial gingival margin trimmer (13-85-10-14, R and small Class II amalgam restorations. In most clinical situations,
L) is used to remove unsupported gingival enamel by the establish- the restoration of these preparations would likely be with composite
ment of a 90-degree gingival cavosurface angle at the gingival unless the patient has high caries risk. If amalgam is used, the
margin (Fig. 10.74). he resulting enamel gingival margin has a features presented should be considered in the tooth preparation
6-centigrade (20-degree) gingival declination. he marginal con- portion of the procedure.
iguration is angled no more than necessary to ensure that full-length
enamel rods form the gingival margin and is no wider than the Mandibular First Premolar
enamel (see Fig. 10.74). When the gingival margin is positioned he technique of the Class II tooth preparation for amalgam for
gingival to the cementoenamel junction (CEJ) (i.e., on the tooth the mandibular irst premolar must be modiied because the
 CHAPTER 10 Clinical Technique for Amalgam Retoration 349

Approximately 20°
to the internal 20°
C
A dentin wall B
• Fig. 10.74 A, The marginal coniguration of the enamel portion of the gingival wall is established with
a gingival margin trimmer to ensure full-length enamel rods forming the gingival margin. B and C, The
sharp angles at the linguogingival and faciogingival corners are rounded by rotational sweeping with a
gingival margin trimmer.

the involved proximal surface is entered with the No. 245 bur.
Immediately after the entry, the bur is directed into the proximal
marginal ridge and then gingivally until the proximal DEJ is visible.
he bur axis for the proximal ditch cut should be parallel to the
tooth crown, which is tilted slightly lingually for mandibular
posterior teeth (see Fig. 10.76C). he proximal enamel is isolated
and the proximal box completed as previously described for the
mandibular second premolar. he bur is then returned to the area
of entry, and the occlusal step is prepared with a dovetail, if needed.
When preparing the occlusal portion, the bur is tilted slightly
• Fig. 10.75 The mandibular irst and second premolars are compared.
lingual to establish the correct pulpal wall direction (which maintains
Note differences in the sizes of the pulp chambers, lingual cusps, and
direction of pulpal walls.
the dentin support for the small lingual cusp and prevents encroach-
ment on the facial pulp horn). he primary diference in tooth
preparation on this tooth, compared with the preparation on other
morphologic structure of this tooth is diferent from other posterior posterior teeth, is the facial inclination of the pulpal wall. he
teeth. he relationship of the pulp chamber to the DEJ and the isthmus is broadened as necessary, but maintains the dovetail
relatively small size of the lingual cusp are illustrated in Fig. 10.75. retention form. Fig. 10.76B illustrates the correct occlusal outline
(his igure also illustrates the correct position of the pulpal wall form. Removing any remaining caries lesion (if present) and inserting
and how it difers in position and orientation compared with the necessary liners, bases, or both precede the placement of proximal
second premolar.) Incorrect preparation of the central groove area grooves and the inishing of the enamel margins (see Fig. 10.76C).
may weaken the lingual cusp, and excessive extension in a facial
direction may approach or expose the facial pulp horn. When Maxillary First Molar
preparing the occlusal portion, the bur is tilted slightly lingually When mesial and distal proximal surface amalgam restorations are
to establish the correct pulpal wall direction (see Fig. 10.43B). indicated on the maxillary irst molar that has an unafected oblique
he mandibular irst premolar presents with unique occlusal ridge, separate two-surface tooth preparations are indicated (rather
morphology, most notably the presence of a large transverse ridge than a mesioocclusodistal preparation). he use of two preparations
of enamel. Most often the coalescence of the enamel lobes is is preferred because the strength of the tooth crown is signiicantly
complete and no caries-prone central issure results. herefore a greater when the oblique ridge is intact.55 he mesioocclusal tooth
caries lesion in the mesial pit or distal pit may be included as part preparation is generally uncomplicated (Fig. 10.77A). Occasionally,
of the Class II preparation, but with an outline form that does extension through the oblique ridge and into the distal pit is
not extend to or across the transverse ridge (Fig. 10.76A). he necessary because of the extent of the caries lesion. he outline of
level of divergence of the facial and lingual proximal walls (see the occlusolingual pit-and-issure portion is similar to that of the
Fig. 10.76B) is such that secondary retention grooves are indicated Class I occlusolingual preparation. Fig. 10.77B and C illustrates
(see Fig. 10.76C). If the opposite pit or proximal surface is faulty, a mesioocclusal preparation extended to include the distal pit and
it is restored with a separate restoration so as to not compromise the outline form that includes the distal oblique and lingual
the resistance form of the tooth. issures.
For a preparation that does not cross the transverse ridge, the When the occlusal issure extends into the facial cusp ridge and
proximal box is prepared before the occlusal portion to prevent cannot be removed by enameloplasty, the defect should be eliminated
removing the tooth structure that will form the isthmus between by extension of the tooth preparation. Occasionally this may be
the occlusal dovetail and the proximal box. he pit adjacent to accomplished by tilting the bur to create an occlusal divergence
350 C HA P T E R 1 0 Clinical Technique for Amalgam Retoration

A B C
• Fig. 10.76 The mandibular irst premolar with a sound transverse ridge. A, A two-surface tooth
preparation that does not include the opposite pit. B, Occlusal outline form. C, Proximal view of the
completed preparation.

he distoocclusal tooth preparation may take one of several

outlines, depending on the occlusal anatomy. he occlusal outline
is determined by the pit-and-issure pattern and by the amount
and extension of the caries lesion. An extension onto the lingual
surface to include a lingual issure should be prepared only after
the distolingual proximal margin is established. his approach may
allow conservation of more tooth structure between the distolingual
wall and the lingual issure extension, resulting in more strength
of the distolingual cusp. It is accomplished by preparing the lingual
issure extension more at the expense of the mesiolingual cusp
than the distolingual cusp. Nevertheless, the distolingual cusp on
A B many maxillary molars may be weakened during the distoocclu-
solingual tooth preparation because of the small cuspal portion
remaining between the lingual issure preparation and the disto-
lingual proximal wall. In addition, removal of the caries lesion
may reveal a weakened distolingual cusp. Reduction of the disto-
lingual cusp and coverage with amalgam is often necessary to
provide the proper resistance form (see the mesioocclusodistolingual
[MODL] example in Clinical Technique for Complex Amalgam
Restorations).

Maxillary First Premolar

D A Class II amalgam tooth preparation involving the mesial surface
C
of a maxillary irst premolar requires special attention because the
• Fig. 10.77 Maxillary irst molar. A, Conventional mesioocclusal prepa- mesiofacial embrasure is esthetically prominent. he occlusogingival
ration. B, Mesioocclusal preparation extended to include the distal pit. preparation of the facial wall of the mesial box should be parallel
C, Mesioocclusolingual preparation, including the distal pit and the distal
to the long axis of the tooth instead of converging occlusally to
oblique and lingual issures. D, Mesioocclusal preparation with facial
issure extension.
minimize an unesthetic display of amalgam in the faciogingival
corner of the restoration. In addition, the facial extension of the
mesiofacial proximal wall should be minimal so that the mesiofacial
of the facial wall while maintaining the dentin support of the proximal margin of the preparation only minimally clears the
ridge. If it is not possible to eliminate this fault without extending contact as the margin is inished with an appropriate enamel hatchet
the margin to the height of the cusp ridge or undermining the or chisel (Fig. 10.78).
enamel margin, the preparation should be extended facially through If the mesial proximal involvement (1) is limited to a issure
the ridge (see Fig. 10.77D). he pulpal wall of this facial extension in the marginal ridge that is at risk for caries, (2) is not treatable
may have remaining enamel, but a depth of 1.5 to 2 mm is necessary by enameloplasty, and (3) does not involve the proximal contact,
to provide suicient bulk of amalgam material for adequate strength then the proximal portion of the tooth preparation is prepared by
(adequate resistance to lexure under load). For the best esthetic extending through the fault with the No. 245 bur so that the
results, minimal extension of the proximal mesiofacial margin is margins are lingual to the contact. Often this means that the
indicated. proximal box is the faciolingual width of the bur, and the gingival
 CHAPTER 10 Clinical Technique for Amalgam Retoration 351

A B
• Fig. 10.78 To produce an inconspicuous margin on the maxillary irst premolar, the mesiofacial wall
does not diverge gingivally, and facial extension with a No. 245 bur should be minimal so that the mesio-
facial proximal margin of the preparation minimally clears the contact as the margin is inished. A, Occlusal
view. B, Facial view.

Tooth Preparation for Cla II Amalgam

Retoration Involving Both Proximal Surface
Perhaps the best indications for the use of amalgam restorations
are moderate and large Class II defects that include both proximal
surfaces and much of the occlusal surface. his section describes
factors to consider when amalgam is used for moderate and large
Class II restorations. he tooth preparation techniques presented
for a two-surface Class II restoration apply to larger Class II restora-
tions as well. When the defect is large, however, certain modiications
in tooth preparation may be necessary.
• Fig. 10.79 A simple box restoration without the occlusal step is per- Occlusal Extensions
missible when restoring a small proximal lesion in the tooth without either Larger Class II defects may require greater extension of the occlusal
occlusal issures or previously inserted occlusal restoration and when the
surface outline form. his may require extending into grooves that
involved marginal ridge does not support occlusal contact. The proximal
grooves extend to the occlusal surface.
are issured, extending the outline form up the cuspal inclines, or
reducing and covering the cusps that have inadequate dentin
support. hese alterations may be accomplished easily by following
the principles presented previously. he depth and extension of
loor may be at the same depth as the pulpal loor. he retention the initial preparation of issures occur at the same initial pulpal
form for this extension is provided by the slight occlusal convergence loor depth (i.e., at the level of the DEJ) and follow the DEJ as
of the facial and lingual walls (see Fig. 10.34). the preparation is extended in a facial or lingual direction.
If the proximal caries lesion is limited to the mesiolingual If an occlusal outline form extends up a cuspal incline, the
embrasure, the mesial proximal contact should not be included extension also should maintain the pulpal loor at the level of the
in the tooth preparation. If only the lingual aspect of the mesial DEJ. his extension usually requires some alteration in the orienta-
proximal contact is carious, the mesiofacial wall may be left in tion of the No. 245 bur—a slight lingual tilt when extending in
contact with the adjacent tooth (reducing the display of amalgam). a facial direction and a slight facial tilt when extending in a lingual
A Class II tooth preparation involving the distal surface of the direction (see Fig. 10.35). Maintaining the correct pulpal loor
maxillary irst premolar is similar to the preparation of the man- depth preserves tooth structure and reduces the potential for pulpal
dibular second premolar described earlier. encroachment. he prepared facial (or lingual) cavosurface margin
still should result in a 90-degree amalgam margin. If it is necessary
Box-Only Preparation to extend through the cusp ridge onto the facial or lingual surface,
When restoring a small, cavitated proximal lesion in a tooth with the preparation is accomplished as described for the occlusolingual
neither occlusal issures nor a previously inserted occlusal restoration, Class I restoration.
a proximal box preparation without an occlusal step has been When the occlusal outline form extends from a primary issure
recommended.54,55 his preparation should be limited to a proximal to within two thirds of the distance to a cusp tip, that cusp is
surface with a narrow proximal contact (allowing minimal facial usually suiciently weakened so as to require reduction and coverage
and lingual extensions) and a marginal ridge with no occlusal with the restoration. Leaving the cusp in a weakened state may
contact. To maximize retention, preparations with facial and lingual be acceptable if the cusp is very large. Routine preparations in
walls that almost oppose each other are recommended. As in the some teeth may predispose some cusps for reduction and coverage
typical preparation, the facial and lingual proximal walls converge with amalgam. he small distal cusp of the mandibular irst molars,
occlusally. Retention grooves are mandatory in box-only prepara- the distolingual cusp of maxillary molars, and the lingual cusp of
tions.117 he proximal retention grooves should have a 0.5-mm some mandibular premolars (especially irst premolars) may be
depth at the gingival point angle and extend occlusally to be visible weakened when normal preparations of surrounding areas of the
in the occlusal outline form (Fig. 10.79). tooth are included. See the section Clinical Technique for Complex
352 C HA P T E R 1 0 Clinical Technique for Amalgam Retoration

Amalgam Restorations for information on when and how to reduce

and cover cusps with amalgam.

Proximal Extensions
Larger Class II caries lesions often require larger proximal box
preparations. hese may include not only increased faciolingual
or gingival extensions but also extension around a facial or lingual
line angle. Large proximal box preparations may also need sec-
ondary retention features (i.e., retention grooves) for adequate
retention form because the proximal external walls are excessively
divergent. Extensive proximal boxes are usually prepared in the • Fig. 10.80 Mesioocclusodistal (MOD) preparation on the mandibular
same fashion as more conservative proximal boxes but may second premolar that had a moderately sized MOD caries lesion.
require modiications. For increased faciolingual extensions, it
may be necessary to tilt the No. 245 bur to include extensive
proximal faults that are gingival to the contact area. Tilting the
bur lingually when extending a facial proximal wall, or facially
when extending a lingual proximal wall, conserves more of the
marginal ridge and cuspal tooth structure. Although this action
enhances preservation of some tooth structure strength, it results
in a more occlusally convergent wall, which increases the dif-
iculty of amalgam condensation in the gingival corners of the
preparation.
When proximal extension around a line angle is necessary, it • Fig. 10.81 Typical three- and four-surface restorations for the maxillary
usually is associated with a reduction of the involved cusp (see irst molar. (See Fig. 10.167 for preparation of the distolingual cusp for
Clinical Technique for Complex Amalgam Restorations). Such coverage with amalgam.)
proximal extension is necessary because of a severely defective (or
fractured) cusp or a cervical lesion that extends from the facial
(or lingual) surface into the proximal area. Often these areas are Mandibular First Premolar
included in the preparation by extending the gingival loor of the When a mesioocclusodistal amalgam tooth preparation is needed
proximal box around the line angle, using the same criteria for for the mandibular irst premolar, the support of the small lingual
preparation as the typical proximal box: (1) Facial (or lingual) cusp may be conserved by preparing the occlusal step more at the
extension results in an occlusogingival wall that has a 90-degree expense of tooth structure facial to the central groove than lingual.
cavosurface margin, and (2) the axial depth is 0.5 mm inside In addition, the bur is tilted slightly lingually to establish the
the DEJ. correct pulpal wall direction. Despite these precautions, the lingual
When the proximal defect is extensive gingivally, isolation of cusp may need to be reduced for coverage with amalgam if the
the area, tooth preparation, matrix placement, and condensation lingual margin of the occlusal step extends more than two thirds
and carving of amalgam are more diicult. If the proximal box is the distance from the central issure to the cuspal eminence (see
extended onto the root surface, the axial wall depth is no longer Clinical Technique for Complex Amalgam Restorations).
dictated by the DEJ. Any root-surface preparation for amalgam
should result in an initial axial wall depth of approximately 0.8 mm. Maxillary First Molar
his axial depth provides appropriate strength for amalgam, limits he mesioocclusodistal tooth preparation of the maxillary irst
any potential pulp compromise, and creates enough dimension molar may require extending through the oblique ridge to unite
for the placement of ~0.25 to 0.5 mm deep retention grooves the proximal preparations with the occlusal step. Extending the
while preserving the strength of the adjacent, remaining marginal preparation through the oblique ridge is indicated only if (1) the
dentin and cementum. he extent of the preparation onto the ridge is undermined by a caries lesion, (2) it is crossed by a deep
root surface, the contour of the tooth, or both may require that issure, or (3) occlusal portions of the separate mesioocclusal and
the bur be tilted toward the adjacent tooth when preparing the distoocclusal outline forms leave less than 0.5 mm of the tooth
gingival loor of the proximal box. his tilting may result in an structure between them. he remainder of the outline form is
axial wall that has two planes, the more gingival plane angled similar to the two-surface outline forms described previously in
slightly internally. It also may cause more diiculty in retention this chapter. Fig. 10.81 illustrates typical three-surface and four-
groove placement. he more occlusal part of the axial wall may surface restorations for this tooth.
be overreduced if the bur is not tilted.
Maxillary Second Molar With a Caries Lesion on the
Distal Portion of the Facial Surface
Example of Moderate Cla II Amalgam Tooth Close examination of the distal portion of the facial surface of the
Preparation That Involve Both Proximal maxillary second molar may reveal decalciication, cavitation, or
Surface both. When enamel is only slightly demineralized (i.e., softened
and rough), polishing with sandpaper disks may eliminate the
Mandibular Second Premolar supericial fault. Careful brushing technique, daily use of luoride
A moderate mesioocclusodistal tooth preparation in a mandibular (i.e., rinses, toothpaste), and periodic applications of a luoride
second premolar is illustrated in Fig. 10.80. Note the similarity varnish may prevent further mineral loss. When decalciication is
with the two-surface mesioocclusal preparation. as deep as the DEJ and a distal proximal caries lesion is also present,
 CHAPTER 10 Clinical Technique for Amalgam Retoration 353

however, the entire distofacial cusp may need to be reduced and distofacial groove. Fig. 10.83 illustrates the ideal distofacial extension
included in a mesioocclusodistofacial tooth preparation. he facial and a preparation design that includes the distal cusp.
lesion may be restored separately if it is judged that the distofacial
cusp would not be signiicantly weakened if left unrestored by
amalgam. In that case the mesioocclusodistal preparation would Modiications in Tooth Preparation for
be restored irst, followed by preparation and restoration of the Proximal Surfaces
facial lesion. When such sequential preparations are contraindicated,
the preparation outline is extended gingivally to include the Slot Preparation for Root Caries
distofacial cusp (just beyond the caries lesion) and mesially to Older patients who have gingival recession that exposes cementum
include the facial groove (Fig. 10.82). he No. 245 bur should be (or dentin) may experience caries lesion development on the
used to create a gingival loor (i.e., shoulder) perpendicular to the proximal root surface that is appreciably gingival to the proximal
occlusal force when extending the distal gingival loor to include contact (Fig. 10.84A). Assuming that the contact does not need
the afected facial surface. Inclusion of distofacial caries often restoring, the tooth preparation usually is approached from the
indicates a gingival margin that follows the gingival tissue level. facial direction and has the form of a slot (see Fig. 10.84B and
he width of the shoulder should be approximately 1 mm (or E). A lingual approach is used when the caries is limited to the
0.5 mm inside the DEJ), whichever is greater. Some resistance linguoproximal surface. Amalgam is particularly indicated for slot
form is provided by the shoulder. A retention groove should be preparations if isolation is diicult.5
placed in the axiofacial line angle of this distofacial extension, he initial outline form is prepared from a facial approach with
similar to the grooves placed in the proximal boxes. For additional a No. 2 or No. 4 bur using high speed and air-water spray. Outline
retention a slot may be placed, as discussed in the section on form extension to sound tooth structure is at a limited depth
Clinical Technique for Complex Amalgam Restorations. axially (i.e., 0.75–1 mm at the gingival aspect [if no enamel is
present], increasing to 1–1.25 mm at the occlusal wall [if the
Mandibular First Molar margin is in enamel]) (see Fig. 10.84B). If the occlusal margin is
he distal cusp on the mandibular irst molar may be weakened in enamel, the axial depth should be 0.5 mm inside the DEJ.
when positioning the distofacial wall and margin. Facial extension During this extension, the bur should not remove any soft dentin
of the distofacial margin to clear the distal contact often places the from the axial wall deeper than the outline form initial depth. he
occlusal outline in the center of the cusp; this dictates relocation remaining soft dentin (if any) is removed during inal tooth
of the margin to provide a sound enamel wall and 90-degree amalgam preparation (see Fig. 10.84C). he external walls should form a
that is not on a cuspal eminence. When the distal cusp is small or 90-degree cavosurface angle. With a facial approach, the lingual
weakened or both, extension of the distal gingival loor and distofacial wall should face facially as much as possible; this aids condensation
wall to include the distal cusp places the margin just mesial to the of amalgam during insertion. he facial wall must be extended to
provide access and visibility (convenience form) (see Fig. 10.84D).
In the inal tooth preparation, the No. 2 or No. 4 bur should be
used to remove any remaining soft dentin on the axial wall. A
liner or base (or both) is applied, as indicated.
A No. 1 4 bur is used to create retention grooves in the occlu-
soaxial and gingivoaxial line angles, 0.2 mm inside the DEJ or
0.3 to 0.5 mm inside the cemental cavosurface margin (see Fig.
10.84D and E). he depth of these grooves is ~0.25 to 0.5 mm
and the bur is directed to bisect the angle formed by the junction
of the occlusal (or gingival) and axial walls. Ideally, the direction
of the occlusal groove is slightly more occlusal than axial, and the
direction of the gingival groove would be slightly more gingival
than axial. A dentin desensitizer may be placed before or after
application of the matrix. he matrix for the slot preparation is
illustrated in Fig. 10.84F.
• Fig. 10.82 Mesioocclusodistofacial preparation of the maxillary Rotated Teeth
second molar showing extension to include moderate to extensive caries
Tooth preparation for rotated teeth follows the same principles as
lesion in the distal half of the facial surface. The outline includes the disto-
facial cusp and the facial groove. The dotted line represents the soft tissue
for normally aligned teeth. he outline form for a mesioocclusal
level. tooth preparation on the rotated mandibular second premolar

A B
• Fig. 10.83 Mandibular irst molar. A, Ideal distofacial extension. B, Entire distal cusp included in
preparation outline form.
354 C HA P T E R 1 0 Clinical Technique for Amalgam Retoration

1-1.25 mm

c d

0.75-0.8 mm
A B C D
Lingual

Cementoenamel
a junction
Rubber dam b
x
y

Optional Facial
wrap-around matrix

Insert wedge from facial to c

lingual if facial embrasure is
larger; and vice versa

E
F Rigid supporting material

• Fig. 10.84 Slot preparation. A, Mesiodistal longitudinal section illustrating a caries lesion. The proximal
contact is not involved. B, Initial tooth preparation. C, Tooth preparation with soft carious dentin removed.
D, The retention grooves are shown in longitudinal section, and the transverse section through plane cd
illustrates the contour of the axial wall and the direction of the facial and lingual walls. E, Preparing the
retention form to complete the tooth preparation. F, Matrix for slot preparation: (a) facial view of wedged
matrix; (b) wedged matrix as viewed in transverse cross section (x), gingival to gingival loor; (c) wedged
matrix as viewed in transverse cross section (y), occlusal to gingival loor.

(Fig. 10.85A) difers from normal in that its proximal box is separated by approximately 0.5 mm or more of sound tooth
displaced facially because the proximal caries lesion involves the structure (Fig. 10.86).54,104
mesiofacial line angle of the tooth crown. When the tooth is rotated
90 degrees and the “proximal” lesion is on the facial or lingual Adjoining Restorations
surface, and orthodontic correction is declined or ruled out, the It is permissible to repair or replace a defective portion of an
preparation may require an isthmus that includes the cuspal existing amalgam restoration if the remaining portion of the original
eminence (see Fig. 10.85B). If the lesion is small, consideration restoration has adequate resistance and retention forms. Adjoining
should be given to slot preparation. In this instance, the occlusal restorations on the occlusal surface occur more often in molars
margin may be in the contact area or slightly occlusal to it (see because the dovetail of the new restoration usually may be prepared
Fig. 10.85C). without eliminating the dovetail of the existing restoration. Where
the two restorations adjoin, care should be taken to ensure that
Unusual Outline Forms the outline of the second restoration does not weaken the amalgam
Outline forms should conform to the restoration requirements of margin of the irst (Fig. 10.87A). he intersecting margins of the
the tooth and not to the classic example of a Class II tooth prepara- two restorations should be at a 90-degree angle as much as possible.
tion. As mentioned earlier, a dovetail feature is not required in he decision to join two restorations is based on the assumption
the occlusal step of a single proximal surface preparation unless a that the irst restoration, or a part of it, does not need to be replaced
issure emanating from the occlusal step is involved in the prepara- and that the procedure for the single proximal restoration (compared
tion. Another example is an occlusal issure that is segmented by with a mesioocclusodistal restoration) is less complicated and
coalesced enamel (as illustrated previously for mandibular premolars conserves tooth structure.
and the maxillary irst molars). his condition should be treated Occasionally, preparing an amalgam restoration in two or more
with individual amalgam restorations if the preparations are phases is indicated, such as for a Class II lesion that is contiguous
 CHAPTER 10 Clinical Technique for Amalgam Retoration 355

A B C
• Fig. 10.85 Restoration outlines for rotated teeth. A, Mesioocclusal outline for the mandibular premolar
with 45-degree rotation. B, Mesioocclusal outline for the mandibular premolar with 90-degree rotation.
C, Slot preparation outline for the restoration of a small mesial lesion involving the proximal contact of
the mandibular premolar with 90-degree rotation.

in General Concepts Guiding Preparation for Amalgam Restorations,

and any inal modiications completed.

Retorative Technique for Cla II Amalgam

Preparation
Desensitizer Placement
A dentin desensitizer is placed on the prepared tooth structure per
manufacturer instructions. Excess moisture is removed without
desiccating the dentin.
• Fig. 10.86 Restoration of the mesioocclusal tooth preparation, with
the central issure segmented by coalesced enamel.
Matrix Placement
he primary function of the matrix is to enable proper restoration
of anatomic contours and contact areas. he qualities of a good
with a Class V lesion. Preparing both lesions before placing amalgam matrix include (1) rigidity, (2) establishment of proper anatomic
introduces condensation problems that may be eliminated by contour, (3) restoration of correct proximal contact relationships,
preparing and restoring the Class II lesion before preparing and (4) prevention of gingival excess, (5) convenient application, and
restoring the Class V lesion (see Fig. 10.87B). It is better to condense (6) ease of removal. The following information presents the
amalgam against a carious wall of the irst preparation than to technique of placement for the universal (Tolemire) and precon-
attempt condensation where no wall exists. toured matrix systems.

Abutment Teeth for a Removable Partial Denture Universal Matrix

When the tooth is an abutment for a removable partial denture he universal matrix system (designed by B.R. Tolemire) is ideally
(RPD), the occlusoproximal outline form adjacent to the edentulous indicated when three surfaces (i.e., mesial, occlusal, distal) of a
region may need additional extension if a rest seat is planned. posterior tooth have been prepared (Fig. 10.89). his system is
Additional extension must be suicient facially, lingually, and axially also commonly used for the two-surface Class II restoration. A
to allow for the rest seat to be in the proximoocclusal restoration deinite advantage of the Tolemire matrix retainer is that it may
without jeopardizing its strength. he facial and lingual proximal be positioned on the facial or lingual aspect of the tooth. However,
walls and the respective occlusal margins must be extended so that lingual positioning requires the contra-angled design of the retainer
the entire rest seat may be prepared in the amalgam without (which may be used on the facial aspect as well) (Fig. 10.90; also
encroaching on the restoration margins. If the rest seat is to be see Fig. 10.89). he retainer and the band are generally stable
within the amalgam, it is recommended that a minimum of 0.5 mm when in place. he retainer is separated easily from the band to
of amalgam be present between the rest seat and the margins (Fig. expedite removal of the matrix system from the tooth. Matrix
10.88A). he portion of the pulpal wall apical to the planned rest bands of various occlusogingival widths are available (see Fig. 10.89).
seat is deepened 0.5 mm so that the total depth of the axiopulpal A small Tolemire retainer is available for use with the primary
line angle measured on the faciolingual wall is 2.5 mm (see Fig. dentition.
10.88B). A rest seat used for a tissue-borne (i.e., distal extension) he universal matrix band itself does not meet all the require-
partial denture may involve amalgam and enamel (see Fig. 10.88C). ments of an ideal matrix band. he conventional, lat universal
In this case, no modiication of the outline form of the tooth matrix band must be shaped (i.e., burnished) to reproduce natural
preparation is indicated (see Fig. 10.88C). Note Fig. 10.88D anatomic contour and resultant proximal contact. Uncontoured
illustrates the relationship of the tissue-borne RPD with the abut- bands are available in two thicknesses, 0.05 mm and 0.038 mm.
ment tooth (see Fig. 10.88C). Burnishing the thinner band to create contour is more diicult,
All aspects of the Class II preparation, regardless of various and the band is less likely to retain its contour when tightened
levels of complexity, should be accomplished with precision. he around the tooth. he uncontoured band must be burnished before
preparation should then be cleaned, carefully inspected as indicated assembling the matrix band and the retainer. Burnishing must
356 C HA P T E R 1 0 Clinical Technique for Amalgam Retoration

A B
• Fig. 10.87 Adjoining restorations. A, Adjoining mesioocclusal tooth preparation with distoocclusal
restoration so that the new preparation does not weaken the amalgam margin of the existing restoration.
B, Preparing and restoring a Class II lesion before preparing and restoring a Class V lesion contiguous
with it eliminates condensation problems that occur when both lesions are prepared before either is
restored.

rs gp

rs

Pontic
gp

A B
RPD framework Tooth-borne RPD

gp

mrs
C D
RPD framework RPD distal extension
• Fig. 10.88 Abutment teeth with Class II restorations designed for a removable partial denture (RPD).
A, Occlusal view showing the location of the rest seat (rs) and the guide plane (gp) for a tooth-borne
RPD. B, Cross-sectional view illustrating deepened pulpal wall in the area of the rest seat (rs) to provide
adequate thickness of amalgam. Note the relationship of the guide planes (gp) to the tooth-borne RPD.
C, Occlusal view showing the mesial rest seat (mrs) for the tissue-borne (i.e., distal extension) RPD pre-
pared partly in a previous MOD amalgam restoration and partly in natural tooth structure. D, Lingual view
of a distal extension RPD showing the relationship of the RPD to the Class II restoration and the guide
plan (gp). Note that the igure shows a M-D cross section through the MOD amalgam and the occlusal
portion of the facial aspect of the distal marginal ridge is visible.
 CHAPTER 10 Clinical Technique for Amalgam Retoration 357

A B
• Fig. 10.89 Straight (A) and contra-angled (B) universal (Toflemire) retainers. Bands with varying
occlusogingival widths are available.

may be justiied as less chair time is required during the restorative

phase. When cotton roll isolation is used, the Tolemire retainer
helps hold the cotton roll in place (Fig. 10.92).
“Burnishing the matrix band” means that the metal band is
intentionally deformed occlusogingivally with a suitable hand
instrument to produce a rounded or convex surface that (when
in place around the tooth) produces a restoration that is symmetric
in contour with the adjacent proximal surface (Fig. 10.93). he
No. 26-28 burnisher is generally recommended for burnishing the
band. he band should be placed on a resilient paper pad because
distortion of the metal matrix will not occur on a hard, nonresilient
• Fig. 10.90 Lingual positioning requires a contra-angled universal
retainer.
surface. he smaller round burnisher tip should irst be used with
irm pressure in back-and-forth, overlapping strokes along the
length of the band until the band is deformed occlusogingivally
occur in the areas corresponding to the proximal surface to be in the appropriate areas. When the band is deformed, the larger
restored after the band is positioned around the tooth. egg-shaped end may be used to smooth the distorted band. If a
Precontoured bands for the universal retainer are commercially convex surface is not obvious in the burnished areas when the
available and need little or no adjustment before being placed in band is removed from the pad, it has not been adequately burnished.
the retainer or after being positioned around the tooth (Fig. 10.91). he band may be burnished with the larger egg-shaped burnisher
Although precontoured bands are more expensive, they generally only, but more work is required to do so. It is not necessary to
are preferred over the uncontoured bands. he diference in cost burnish the entire length of the band; focus efort only on distorting
358 C HA P T E R 1 0 Clinical Technique for Amalgam Retoration

• Fig. 10.92 Toflemire retainer maintaining a cotton roll in the maxillary

vestibule during condensation.

• Fig. 10.91 Precontoured bands for a universal retainer. Pictured:

Waterpik Getz Contour Matrix Bands. (Courtesy Water Pik Inc., Fort
Collins, CO.)

A B

C
• Fig. 10.93 Burnishing the matrix band. A, With the band on the pad, a small burnisher is used to
deform the band. B, A large burnisher used to smooth the band contour. C, Burnished matrix band for
mesioocclusodistal tooth preparation. (Courtesy Aldridge D. Wilder, DDS.)
 CHAPTER 10 Clinical Technique for Amalgam Retoration 359

the matrix where the proximal contact areas are planned avoided. Care should be taken not to trap the rubber dam between
to occur. the band and the gingival margin. If the dam material is trapped
To prepare the retainer to receive the band, the larger of the between the band and the tooth, the septum of the dam should
knurled nuts is turned counterclockwise until the locking vise is be stretched and depressed gingivally to reposition the dam material.
positioned adjacent to the guide channel on the end of the retainer Once the matrix band is in place, the larger knurled nut is rotated
(Fig. 10.94A). Next, while holding the large nut, the dentist turns clockwise to tighten the band slightly. he explorer should be used
the smaller knurled nut counterclockwise until the pointed spindle along the gingival margin to determine that the gingival edge of
is free of the slot in the locking vise (see Fig. 10.94B). he matrix the band extends beyond the preparation margins. When the band
band is folded end to end, forming a loop (see Fig. 10.94C). When is correctly positioned, the band is securely tightened around the
the band is folded, the gingival edge has a smaller circumference tooth.
as compared with the occlusal edge so as to accommodate the When one of the proximal margins is deeper gingivally, the
diference in tooth circumferences at the gingival and, the more Tolemire mesioocclusodistal band may be modiied to prevent
occlusal, contact levels. he band is positioned in the retainer so damage to the gingival tissue or attachment on the more shallow
that the slotted side of the retainer is directed gingivally to permit side. he band may be trimmed for the shallow gingival margin,
easy subsequent separation (in an occlusal direction) of the retainer permitting the matrix to extend farther gingivally for the deeper
from the band after the restoration has been inserted. his is gingival margin (Fig. 10.95).
accomplished by placing the occlusal edge of the band in the he mouth mirror is positioned lingually to observe the proximal
correct guide channel (i.e., right, left, or parallel to the long axis contours of the matrix through the interproximal space (Fig. 10.96).
of the retainer), depending on the location of the tooth. he two he occlusogingival contour should be convex, with the height of
ends of the band are placed in the slot of the locking vise so that contour at proper contact level such that the metal band is touching
the ends are aligned with the edge of the vice, and the smaller of the adjacent proximal surface in the precise location where the
the knurled nuts is turned clockwise to tighten the pointed spindle contact should occur. he matrix is also observed from an occlusal
against the band within the locking vice (see Fig. 10.94D). If aspect allowing evaluation of the position of the contact area in a
proximal wedges were used during tooth preparation, the wedges faciolingual direction. If proper proximal contour and contact is
are removed at this point and the matrix band is itted around the not observed, it may be necessary to remove the retainer and
tooth (allowing the gingival edge of the band to be positioned at reburnish the band. Minor alterations in contour and contact may
least 1 mm apical to the gingival margin). Damaging the gingival be accomplished without removal from the tooth. he backside
attachment with the sharp edge of the matrix band should be of the blade of the 15-8-14 spoon excavator (i.e., Black spoon) is

Guide channel

A B

C D
• Fig. 10.94 Positioning the band in a universal retainer. A, Explorer pointing to the locking vise located
immediately adjacent to the guide channel. B, The pointed spindle is released from the locking vise when
the small knurled nut is turned counterclockwise. C, The band is folded to form a loop and to be posi-
tioned in the retainer (occlusal edge of band irst). The gingival aspect of the vise is shown in this view.
D, The spindle is tightened against the band in the locking vise. (From Daniel SJ, Harfst SA, Wilder RS:
Mosby’s dental hygiene: Concepts, cases, and competencies, ed 2, St. Louis, Mosby, 2008.)
360 C HA P T E R 1 0 Clinical Technique for Amalgam Retoration

excellent for improving contour in the area where the proximal After the matrix contour and extension are evaluated, a wedge
contact is to occur. If a smaller burnishing instrument is used, the is placed in the gingival embrasure(s) using the following technique:
dentist should use care not to create a grooved or bumpy surface (1) Break of approximately 1.2 cm of a round toothpick; (2) grasp
that would result in a restoration with an irregular proximal surface. the broken end of the wedge with the No. 110 pliers; (3) insert
Ideally the band should be positioned 1 mm apical to the gingival the pointed tip from the lingual or facial embrasure (whichever is
margin or deep enough to be engaged by the wedge (whichever larger), slightly gingival to the gingival margin; and (4) wedge the
is less) and 1 to 2 mm above the adjacent marginal ridge(s) to band tightly against the tooth and margin (Fig. 10.97A). he
allow for adequate condensation of the amalgam in the marginal wedge may be lightly moistened with water or a water-soluble
ridge areas. A minor modiication of the matrix may be indicated lubricant to facilitate its placement. If the wedge is placed occlusal
for restoring the proximal surface that is planned for a guide plane to the gingival margin, the band is pressed into the preparation,
for a RPD. which will result in an abnormal concavity in the proximal surface
of the restoration (see Fig. 10.97B). he wedge should not be so
far apical to the gingival margin that the band will not be held
tightly against the gingival margin. his improper wedge placement
results in gingival excess of amalgam (i.e., amalgam “overhang”)
caused by the band moving slightly away from the margin during
condensation of the amalgam. Such an overhang often goes
undetected and may result in irritation of the gingiva or an area
of plaque accumulation, which may increase the risk of secondary
caries. If the wedge is signiicantly apical of the gingival margin,
a second (usually smaller) wedge may be placed on top of the irst
to wedge adequately the matrix against the margin (Fig. 10.98).
his type of wedging is particularly useful for patients whose
interproximal tissue level has receded.
he gingival wedge should be tight enough to prevent any
possibility of an overhang of amalgam in at least the middle two
thirds of the gingival margin (see Fig. 10.98A and B). Occasionally,
double wedging is permitted (if access allows), securing the matrix
• Fig. 10.95 The band may be trimmed for the shallower gingival when the proximal box is wide faciolingually. Double wedging refers
margin, permitting the matrix to extend farther gingivally for the deeper
gingival margin on the other proximal surface.
to using two wedges: one from the lingual embrasure and one
from the facial embrasure (see Fig. 10.98E and F). Two wedges
help ensure that the gingival corners of a wide proximal box may
be properly condensed; they also help minimize gingival excess.
Double wedging should be used only if the middle two thirds of
the proximal margins are not able to be adequately wedged. Any
amalgam excess that forms in the facial and lingual corners is
accessible to carving, and therefore proper wedging to prevent
gingival excess of amalgam in the middle two thirds of the proximal
box (see Fig. 10.98B) is the primary objective.
Occasionally a concavity may be present on the proximal surface
that is adjacent to the gingival margin. his may occur on a surface
with a luted root, such as the mesial surface of the maxillary irst
premolar (see Fig. 10.98G1). A gingival margin located in this
area may be concave (see Fig. 10.98G2). To wedge a matrix band
tightly against such a margin, a second pointed wedge may be
• Fig. 10.96 Using a mirror from the facial or lingual position to evaluate
inserted between the irst wedge and the band (see Fig. 10.98G3
the proximal contour of the matrix band. and G4).

Incorrect
A B
• Fig. 10.97 A, Correct wedge position. B, Incorrect wedge positions.
 CHAPTER 10 Clinical Technique for Amalgam Retoration 361

Triangular or round wedge

for moderately extended
A gingival margin C
B

Double-wedging

D
E
Rigid supporting material:
most wedges should
G1 Fluting Fluting results in
be anchored by rigid
opening between
supporting material
matrix and gingival
to forestall any loosening
margin
F of wedges during amalgam
condensation
G2

G4
G3

Wedge-wedging Testing with explorer

a matrix, ready for rigid supporting material; in a press-scape motion for
wedges inserted from lingual or soundness of enamel margin
G facial embrasure, whichever is larger and tightness of matrix to margin

• Fig. 10.98 Various double-wedging techniques. A and B, Proper wedging for the matrix for a typical
mesioocclusodistal preparation. C and D, Technique to allow wedging near the gingival margin of the
preparation when the proximal box is shallow gingivally, the interproximal tissue level has receded, or
both. E and F, Double wedging may be used with faciolingually wide proximal boxes to provide maximal
closure of the band along the gingival margin. G, Another technique may be used on the mesial aspect
of the maxillary irst premolars to adapt the matrix to the luted (i.e., concave) area of the gingival margin
(G1, G2); a second wedge inserted from the lingual embrasure (G3); testing the adaptation of the band
after insertion of the wedges from the facial aspect (G4).
362 C HA P T E R 1 0 Clinical Technique for Amalgam Retoration

he wedging action between teeth should provide enough separa- attempts to remove the wedge (using the explorer with moderate
tion of adjacent teeth to compensate for the thickness of the matrix pressure) after irst having set the explorer tip into the wood near
band. his ensures a positive contact relationship after the matrix the broken end. Moderate pulling should not cause dislodgment.
is removed (after the condensation and initial carving of amalgam). Often the rubber dam has a tendency to loosen the wedge through
If a Tolemire retainer is used to restore a two-surface Class II rebounding of the dam stretched during wedge placement. Lubrication
preparation, the single wedge must provide enough separation to of the wedge and stretching the interproximal dam septa, in the
compensate for two thicknesses of band material. he tightness of direction opposite to the direction of wedge placement, before and
the wedge is tested by pressing the tip of an explorer irmly at several during wedge placement may prevent rebound dislodgment. he
points along the middle two thirds of the gingival margin (against stretched dam is released after the wedge is inserted.
the matrix band) to verify that it cannot be moved away from the Some situations may require a triangular wedge that is modiied
gingival margin (Fig. 10.99). As an additional test, the dentist (by knife or scalpel blade) to conform to the approximating tooth
contours (Fig. 10.100). he round toothpick wedge is usually the
wedge of choice with conservative proximal boxes, however, because
its wedging action is more occlusal (i.e., nearer the gingival margin)
than with the triangular wedge (Fig. 10.101A and B).
he triangular (i.e., anatomic) wedge is recommended for a
preparation with a deep gingival margin. he triangular wedge is
positioned similarly to the round wedge, and the goal is the same.
When the gingival margin is deep (cervically), the base of the
triangular wedge more readily engages the tooth gingival to
the margin without causing excessive soft tissue displacement. he
anatomic wedge is preferred for deeply extended gingival margins
because its greatest cross-sectional dimension is at its base (see Fig.
10.101C and D).
To maintain gingival isolation attained by an anatomic wedge
• Fig. 10.99 Use of the explorer tip (with pressure) to ensure proper
placed before the preparation of a deeply extended gingival margin,
adaptation of the band to the gingival margin.

Tall triangular wedge

incorrect for minimally
A extended gingival margin
B

Corrective
trimming
of wedge

C D

• Fig. 10.100 Modiied triangular (i.e., anatomic) wedge. A, Depending on the proximal convexity, a
triangular wedge may distort the matrix contour. B, A sharp-bladed instrument may be used to modify
the triangular steepness of the wedge. C, Modiied and unmodiied wedges are compared. D, Properly
modiied triangular wedge prevents distortion of the matrix contour.
 CHAPTER 10 Clinical Technique for Amalgam Retoration 363

A Incorrect B Correct

C Incorrect D Correct
• Fig. 10.101 Indications for the use of a round toothpick wedge versus a triangular (i.e., anatomic)
wedge. A, As a rule, the triangular wedge does not irmly support the matrix band against the gingival
margin in conservative Class II preparations (arrowhead). B, The round toothpick wedge is preferred for
these preparations because its wedging action is nearer the gingival margin. C, In Class II preparations
with deep gingival margins, the round toothpick wedge crimps the matrix band contour if it is placed
occlusal to the gingival margin. D, The triangular wedge is preferred with these preparations because its
greatest width is at its base.

it may be appropriate to withdraw the wedge a small distance to Hollenback carver blade
allow passage of the band between the loosened wedge and the
gingival margin. Tilting (i.e., canting) the matrix into place helps
the gingival edge of the band slide between the loosened wedge
and the gingival margin. he band is tightened, and the same
wedge is irmly reinserted.
Supporting the matrix material with the blade of a Hollenback
carver during the insertion of the wedge for the diicult deep
gingival restoration may be helpful.55 he tip of the blade is placed
between the matrix and the gingival margin, and then the “heel”
of the blade is leaned against the matrix and adjacent tooth (Fig.
10.102). In this position, the blade supports the matrix to help
in positioning the wedge suiciently gingivally and preventing the
wedge from pushing the matrix into the preparation. After the
wedge is properly inserted, the blade is gently removed. • Fig. 10.102 Supporting the matrix with the blade of a Hollenback
All aspects of the band and wedge are assessed, and any desired carver during wedge insertion.
inal corrections are made. he matrix band and wedge must provide
appropriate proximal contact and contour (see Fig. 10.96). After
wedging, relaxing the tension of the band by turning the larger burnishes for appropriate occlusogingival contour (in the contact
knurled nut of the Tolemire retainer a quarter turn counterclock- areas), and inserts the band into the Tolemire retainer.
wise will help to ensure proximal contact. If loosening the Tolemire Occasionally the interdental spacing is so large that a suitably
band still does not allow for contact with an adjacent tooth, a trimmed tongue blade is required to wedge the matrix (Fig. 10.104).
custom-made band with a smaller angle may be used. Reducing Occasionally it is impossible to use a wedge to secure the matrix
the angle of the band increases the diference in length (i.e., cir- band. In this case the band must be suiciently tight to minimize
cumferences) of the gingival and occlusal edges. To reduce the the gingival amalgam excess. Because the band is not wedged,
angle of the band, the operator folds it as shown in Fig. 10.103, special care must be exercised to place small amounts of amalgam
364 C HA P T E R 1 0 Clinical Technique for Amalgam Retoration

Occlusal edge

Gingival edge
a

• Fig. 10.103 The custom-made matrix strip is folded, as indicated by

arrows. The smaller angle (a) compared with the angle of the commercial
strip increases the difference between the lengths of the gingival and
occlusal edges.
• Fig. 10.104 A custom-made tongue blade wedge may be used when
excessive space exists between adjacent teeth.

C
B
A

D E

F
• Fig. 10.105 Rigid material–supported sectional matrix. A, The shape of the stainless steel strip after
trimming. B, The strip contoured to the circumferential contour of the tooth (ingers can be used).
C, Burnishing the strip to produce occlusogingival contact contour (left and right arrows indicate the short,
back-and-forth motion of the burnisher). D, Contoured strip in position. E, Matrix strip properly wedged.
F, Completed rigid material–supported sectional matrix.

in the gingival loor and condense the irst 1 mm of amalgam Rigid-Material Supported Sectional Matrix
lightly but thoroughly in a gingival and lateral direction. he An alternative to the universal matrix band is the use of a properly
condensation of additional increments is then carefully continued contoured sectional matrix that is wedged and supported by a
in a gingival direction using a larger condenser with irm pressure. material that is rigid enough to resist condensation pressure. he
Condensation against an unwedged matrix may cause a gross supporting material selected must be easy to place and to remove.
extrusion of amalgam beyond the gingival margin. he excess Examples include light-cured, thermoplastic, and quick-setting
amalgam must be removed with a suitable carver immediately rigid polyvinyl siloxane (PVS) materials (Fig. 10.105). he gingival
after matrix removal. wedge is positioned interproximally to secure the band tightly at
 CHAPTER 10 Clinical Technique for Amalgam Retoration 365

the gingival margin to prevent any excess of amalgam (i.e., over- he matrix should be tight against the facial and lingual margins
hang). he wedge also separates teeth slightly to compensate for on the proximal surface so that the amalgam may be well condensed
the thickness of the section of matrix material. he wedge is placed at the preparation margins. In addition, when the matrix is tight
before the application of rigid supporting material. against the tooth, minimal carving is necessary on the proximal
he proximal surface contour of the matrix should allow the margins after the matrix is removed.
normal slight convexity between the occlusal and middle thirds
of the proximal surface when viewed from the lingual (and facial) Precontoured Sectional Matrix Strips
aspect. Proximal surface restorations often display an occlusogingival Commercially available sectional metal strips (e.g., Palodent System;
proximal contour that is too straight, thereby causing the contact DENTSPLY Caulk, Milford, DE) are precontoured and ready for
relationship to be located too far occlusally (with little or no occlusal application to the tooth (Fig. 10.108). hese strips have limited
embrasure). his condition allows food impaction between teeth, application when used for amalgam because of their rounded
with resultant injury to the interproximal gingiva and supporting contour. hey usually are most suitable for mandibular irst pre-
tissues, and invites conditions leading to demineralization of the molars and the distal surface of maxillary canines. he contact
adjacent proximal surfaces. he proximal surface contour of the area of the adjacent tooth occasionally is too close to allow placement
matrix should also provide the correct form to the proximal line of the contoured Palodent strip without causing a dent in the
angles, both facially and lingually. If these contours are not present, strip’s contact area, making it unusable.
the facial and lingual embrasures of the restoration are too open,
inviting food impaction and injury to underlying supporting tissues. Condensation and Carving of the Amalgam
Correct and incorrect contours and matrix correction steps are Proper condensation of amalgam results in close material adaptation
illustrated in Figs. 10.106 and 10.107. to the preparation walls (limiting marginal voids) and minimal
inclusion of internal voids. In addition, careful overstepping
condensation technique eliminates excess mercury and results in
a stronger restoration that is less prone to corrosion. Care should
be taken to choose condensers that are best suited for use in each
part of the tooth preparation and that may be used without binding
in the preparation or between the preparation and the matrix
Wrong
band.
Condensation should occur in the proximal box(es) irst by
transfer of enough amalgam with the amalgam carrier to ill the
gingival portion by about 1 mm. his irst increment is condensed
in a gingival and lateral direction with suicient force to adapt
the amalgam to the gingival loor. Additional amalgam is carefully
condensed against the proximal margins of the preparation and
into the proximal retention grooves (if present). Firm, facially and
• Fig. 10.106 Alteration of the sectional matrix contour to provide the
lingually directed condensation (i.e., lateral condensation) with
correct form to the proximofacial line angle region.
the side of the condenser should be accomplished along with the
application of gingivally directed force (Fig. 10.109).118 Condensa-
tion strokes in a gingival and lateral direction help to ensure that
no voids occur internally or at the faciogingival or linguogingival
line angles. Mesial (or distal) condensation of the amalgam in the
proximal box is accomplished to ensure proper contour and proximal
contact with the adjacent tooth.

Correct

Embrasure

Too closed Too open

Precontoured
metal strips

Incorrect
• Fig. 10.107 Correct or incorrect facial and lingual embrasure form is • Fig. 10.108 Precontoured metal strips. (The Palodent System; cour-
determined by the shape of the sectional matrix strip. tesy of DENTSPLY Caulk, Milford, DE.)
366 C HA P T E R 1 0 Clinical Technique for Amalgam Retoration

• Fig. 10.110 Precarve burnishing with a large burnisher. (Courtesy

• Fig. 10.109 Lateral and occlusogingival force is necessary to con- Aldridge D. Wilder, DDS.)
dense amalgam properly into the proximal grooves and into the angles at
the junction of the matrix band and the margins of the preparation.

The procedure of adding and condensing continues until

amalgam reaches the level of the pulpal wall. he size of the
condenser is changed (usually to a larger one), if indicated, and
amalgam is condensed in the remaining proximal portion of the
preparation concurrently with the occlusal portion. It may be
necessary to return to a smaller condenser when condensing in a
narrow extension of the preparation or near the proximal margins.
A smaller condenser face is more efective at condensing, provided
it does not signiicantly penetrate the amalgam already in place.
he occlusal margins are covered and overpacked by at least 1 mm
using a large condenser, ensuring that the margins are well con-
densed, especially in the area of the marginal ridge. 119 Proper
condensation of the amalgam in the marginal ridge area(s) reduces
the risk of marginal ridge fracture during matrix removal. he • Fig. 10.111 Using No. 110 pliers, the matrix band should be removed
plasticity and wetness of the amalgam mass should be monitored in a linguoocclusal (arrow) or facioocclusal direction (not just in an occlusal
during condensation. Proper condensation requires that the mix direction).
should be neither wet (i.e., mercury rich) nor dry and crumbly
(i.e., mercury poor). Amalgam that is beginning to set should be
discarded and a new mix obtained to complete the condensation. embrasure. If the restoration has extensive proximal involvement
Before carving procedures are initiated, precarve burnishing of the of the tooth, the occlusal carving should be accomplished quickly.
occlusal portion with a large egg-shaped or ball burnisher should
be accomplished (Fig. 10.110).79 As mentioned previously, precarve Removal of the Matrix Band and Completion of Carving
burnishing is a form of condensation. At the appropriate time, the matrix retainer irst is removed from
the band by turning the small knurled nut counterclockwise to
Carving the Occlusal Portion retract the pointed spindle from the vice. he end of an index
Carving of the occlusal portion (including the occlusal embrasure inger may be placed on the occlusal surface of the tooth and
or embrasures) may be accomplished with the matrix assembly in matrix band to provide stabilization while the retainer is removed.
place while the amalgam is reaching its initial set. Early removal Next, any rigid supporting material, if used, is removed. he matrix
of the band increases the risk of marginal ridge fracture. Careful band is removed next. he No. 110 pliers are used to tease the
carving of the occlusal portion should begin immediately after band free, from one contact area at a time, by pushing or pulling
condensation and burnishing. Sharp discoid instruments of suitable the band in a linguoocclusal (or facioocclusal) direction and, if
size as well as the Hollenback carver may be efective at reestablishing possible, in the direction of wedge insertion (Fig. 10.111). he
the occlusal anatomy. he marginal ridge is carved conluent with wedge may be left in place to provide separation of teeth while
the tooth’s anatomy such that it duplicates the height and shape the matrix band is removed, and then subsequently removed. By
of the adjacent marginal ridge (see Fig. 10.18). An explorer or maintaining slight interdental separation, the wedge reduces the
small Hollenback carver may be used to carefully deine the occlusal risk of fracturing the newly condensed marginal ridge(s). Band
embrasure. Remembering the pattern of occlusal contacts (that removal in a straight occlusal direction should be avoided so as to
were evaluated before tooth preparation), observing the height of limit the risk of marginal ridge fracture.
the adjacent marginal ridge, and knowing where the preparation Matrix band removal allows access to carve the proximal portions
cavosurface margins are located all aid in completing the carving of the restoration. Eicient use of time is required so as to gain
of the occlusal surface, including the marginal ridge and occlusal access to the proximal areas while the amalgam remains carvable.
 CHAPTER 10 Clinical Technique for Amalgam Retoration 367

Proper matrix form should result in a proximal surface that is Guiding Restoration with Amalgam. Finishing and polishing of
nearly completed, with proper contact evident and minimal carving the proximal surface may be indicated where the proximal amalgam
required except to remove a possible small amount of excess amalgam is accessible. his area usually includes the facial and lingual margins
at the proximal facial and lingual margins, at the faciogingival and and areas occlusal to the contact. he remainder of the proximal
linguogingival corners, and along the gingival margin. Amalgam surface is often inaccessible; however, the matrix band should have
knives (scalers, No. 34 and No. 35) are ideal for removing gingival imparted suicient smoothness to it.
amalgam excess (see Figs. 10.21 and 10.22). hey also are ideal If amalgam along the facial and lingual proximal margins was
for reining the embrasure form around the proximal contacts (see slightly overcarved, the enamel margin may be felt as the explorer
Fig. 10.19). he secondary (or “back”) edges on the blades of tip passes from amalgam across the margin onto the external enamel
amalgam knives are occasionally helpful, using a push stroke. he surface. Finishing burs or sandpaper disks, rotating at slow speed,
Hollenback carver No. 3 and (occasionally) the side of the explorer may be used to smooth the enamel–amalgam margin. Sandpaper
may also be suitable instruments for carving these areas. However, disks also may be used to smooth and contour the marginal ridge.
the explorer may not reine the margins and contour as efectively Inappropriate use of sandpaper disks may “ledge” the restoration
as the amalgam knife if the set of the amalgam is close to completion. around the contact, however, resulting in inappropriate proximal
When the proximal carving is completed, the occlusal surface contours.
contouring is completed. Occasionally, occlusal contouring may In small preparations, the facial and lingual proximal margins
require the use of an abrasive stone or inishing bur if the setting are generally inaccessible for inishing and polishing. Fine abrasive
of the amalgam is nearing completion. disks or the tip of a sharpened rubber polishing point or edge of
When carving the margins of the restoration, the cutting surface a sharped abrasive rubber polishing cup may be used to polish the
of the carving instrument is held in a perpendicular orientation. proximal portion that is accessible. When proximal margins are
Carving should be parallel to the margins, however, with the adjacent inaccessible to inishing and polishing with disks or rubber polishing
tooth surface being used to guide the carver. he existence of the points, and some excess amalgam remains (e.g., at the gingival
proximal contact is veriied visually by using the mouth mirror. corners and margins), amalgam knives occasionally may be used
When carving is completed, the rubber dam is removed and the to trim amalgam back to the margin and to improve the contour,
occlusion is assessed and adjusted, as needed. though a lame-shaped inishing bur may ultimately be required.
Abutment teeth for a tooth-supported RPD must provide Fig. 10.112 provides an example of a inished and polished Class
amalgam contour to allow deining (by carving or [later] disking) II amalgam restoration.
a guide plane extending from the marginal ridge 2.5 mm gingivally.
Normal proximal contour, rather than leaving an overcontour, is Quadrant Dentistry
usually suicient, however, and best for the development of a guide When several teeth in a quadrant have caries lesions, the experienced
plane. Guide plane development results in a gingival embrasure dentist usually treats them all at the same appointment rather than
between the natural tooth and RPD framework that is less open individually. Quadrant dentistry increases eiciency and reduces
and less likely to trap food (see Fig. 10.88B and D). chair time for the patient. he use of the rubber dam is particularly
An amalgam restoration of a proximal abutment tooth for a important in quadrant dentistry. For maximal eiciency, when a
tissue-supported (i.e., distal extension) RPD is carved to provide a quadrant of amalgam tooth preparations is planned, each rotary
guide plan and adequate gingival embrasure space (see Fig. 10.88D). or hand instrument should be used on every tooth where it is
his allows for protection of the distogingival tissue, associated with needed before being exchanged.
the distal abutment, when occlusal loading of the RPD distal extension When restoring a quadrant of Class II amalgam tooth prepara-
causes compression of the alveolar ridge soft tissue. tions, it is permissible to apply matrix bands on alternate prepara-
Before the patient is dismissed, thin unwaxed dental loss may tions in the quadrant and restore teeth two at a time. Banding
be passed through the proximal contact(s) once to remove any adjacent preparations requires excessive wedging to compensate
amalgam shavings on the proximal surface of the restoration and for a double thickness of band material and makes the control of
to assess the gingival margin. Passing the loss multiple times through proximal contours and interproximal contacts diicult. Extensive
the contact area of an amalgam that is still early in its set may tooth preparations may need to be restored one at a time. If proximal
result in removal of some surface amalgam and loss of contact boxes difer in size, teeth with smaller boxes should be restored
with the adjacent tooth. When positioned in the gingival embrasure, irst because often the proximal margins are inaccessible to carving
the loss is wrapped around the restored tooth and positioned if the larger adjacent box is restored irst. In addition, smaller
apical to the gingival margin of the restoration. he loss is moved boxes may be restored more quickly and accurately because more
in an occlusogingival direction. he loss not only removes amalgam tooth structure remains to guide the carver. If the larger proximal
shavings but also smooths the proximal amalgam and detects any box is restored irst, the gingival contour of the restoration may
gingival overhang of amalgam. If an overhang is detected, further be damaged when the wedge is inserted to secure the matrix band
use of an amalgam knife is necessary.120 Alternatively, a inishing for the second, smaller restoration. If the adjacent proximal boxes
strip may be used to remove the amalgam excess and inish the are similar in size, the banding of alternate preparations should
proximal surface gingival to the contact area. Floss also may be be started with the most posterior preparation because this allows
used to verify that the intensity of the contact is similar to that the patient to close slightly as subsequent restorations are inserted
of neighboring teeth. Final rinsing and evacuation of the oral (Fig. 10.113).
cavity is then accomplished. he patient is advised to avoid chewing Before restoring the second of two adjacent teeth, the proximal
with the restored tooth for 24 hours. contour of the irst restoration should be carefully established. Its
anatomy serves as the guide to establish proper proximal contours
Finishing and Polishing of the Amalgam leading to correct embrasure forms and contact position/size. If
Finishing and polishing of the occlusal surface of the Class II necessary, a inishing strip may be used to reine the contour of
amalgam should follow the approach presented in General Concepts the irst proximal amalgam (Fig. 10.114). he inishing strip is
368 C HA P T E R 1 0 Clinical Technique for Amalgam Retoration

A B C
• Fig. 10.112 Polished mesioocclusal amalgam restoration. Note the conservative extension. A, Occlu-
sal view. B, Mesiofacial and occlusal views of the mesiofacial margin. C, Facial and occlusal views of the
proximal surface contour and the location of the proximal contact.

• Fig. 10.113 Quadrant dentistry. Unless otherwise indicated, a quad-

rant of Class II preparations with similarly sized proximal boxes may be
restored using two bands simultaneously if they are placed on every other
prepared tooth. It is recommended that the most distal tooth be restored
irst.

B
indicated, however, only where the proximal clearance is present.
Using a inishing strip between contacting amalgam restorations
may compromise or eliminate the proximal contact. Properly placed
amalgam restorations have the potential to last for decades (Fig.
10.115).

Clinical Technique for Cla III

Amalgam Retoration
Class III restorations are indicated for defects located on the
proximal surface of anterior teeth that do not afect the incisal
edge. Part of the facial or lingual surfaces also may be involved. C
he Class III amalgam restoration is rarely used and has been
supplanted by tooth-colored restorations (primarily composite), • Fig. 10.114 When the irst of two adjacent Class II preparations is
restored, proper contour may be established by using a inishing strip
which have become increasingly wear resistant and color stable. before the second is restored. A, Before using the strip. B, Removing the
For esthetic reasons, use of amalgam is best suited for caries lesions over-contour. C, Veriication of proper contour may be accomplished by
that may be accessed from the lingual rather than from the facial. viewing the restoration with a mirror from the occlusal, facial, and lingual
he Class III amalgam restoration is generally reserved for the positions. The proximal contour also may be evaluated after matrix place-
distal surface of maxillary and mandibular canines if (1) the ment by noting the symmetry between the restored surface and the
preparation is extensive with only minimal facial involvement, (2) burnished matrix band.
 CHAPTER 10 Clinical Technique for Amalgam Retoration 369

A B C
• Fig. 10.115 Clinical examples of long-term amalgam restorations: A, 44-year-old amalgams;
B, 58-year-old amalgams in the irst molar; C, 65-year-old amalgams in molars. (A and B, Courtesy Drs.
John Osborne and James Summitt.)

Initial Tooth Preparation

Bur size selection depends on the size of the lesion. Bur options
may include a No. 2 (or smaller) round bur or a No. 330 bur.
he bur is positioned so that the entry cut penetrates into the
caries lesion, which is usually slightly gingival to the contact area.
Ideally the bur is positioned so that its long axis is perpendicular
to the lingual surface of the tooth, but directed at a mesial angle
as close to the adjacent tooth as possible. (he bur position may
be described as perpendicular to the distolingual line angle of the
tooth.) his position conserves the marginal ridge enamel (Fig.
10.117A–C). Penetration through enamel positions the bur so
that additional cutting isolates the proximal enamel afected by
the caries lesion and removes some or all of the soft dentin. In
addition, penetration should be at a limited initial axial depth
• Fig. 10.116 Restoration for Class III tooth preparation using facial (i.e., 0.5–0.6 mm) inside the DEJ (see Fig. 10.117C and D) or
approach on mandibular canine. The restoration is 5 years old. (Courtesy at a 0.75- to 0.8-mm axial depth when the gingival margin is on
Dr. C.L. Sockwell.)
the root surface (in cementum/dentin) (Fig. 10.118). his 0.75-mm
axial depth on the root surface allows a 0.25-mm distance (the
diameter of the No. 1 4 bur is 0.5 mm) between the retention
groove (which is placed later) and the gingival cavosurface margin.
the gingival margin primarily involves cementum, and/or (3) Soft dentin that is deeper than this limited initial axial depth is
moisture control is diicult. removed later during inal tooth preparation.
For a small lesion, the facial margin is extended 0.2 to 0.3 mm
Initial Procedures into the facial embrasure (if necessary), with a curved outline
Appropriate review of the patient record (including medical history), from the incisal to the gingival margin (resulting in a less visible
treatment plan, and radiographs should be accomplished. Anesthesia margin). he lingual outline blends with the incisal and gingival
is usually necessary when a vital tooth is to be restored. he gingival margins in a smooth curve, creating a preparation with little or
extension of the preparation should be anticipated. Prewedging no lingual wall. he cavosurface angle should be 90 degrees at all
in the gingival embrasure of the proximal site to be restored provides margins. he facial, incisal, and gingival walls should meet the
(1) better protection of soft tissue and the rubber dam, (2) better axial wall at approximately right angles (although the lingual wall
access because of the slight separation of teeth, and (3) better meets the axial wall at an obtuse angle or may be continuous with
reestablishment of the proximal contact. he use of a rubber dam the axial wall) (Figs. 10.119 and 10.120). If a large round bur is
is generally recommended; however, cotton roll isolation is also used, the internal angles are more rounded. he axial wall should
acceptable. be uniformly deep into dentin and follow the faciolingual contour
of the external tooth surface (see Fig. 10.120). he initial axial wall
Tooth Preparation for Cla III depth may be in irm dentin (i.e., shallow lesion), in soft dentin
(i.e., moderate to deep lesion), or in existing restorative material,
Amalgam Retoration if a restoration is being replaced.
A lingual access preparation on the distal surface of the maxillary Incisal extension to remove carious tooth structure may eliminate
canine is described here because the use of amalgam in that location the proximal contact (Fig. 10.121). It is important to conserve as
is more likely. A facial approach for a mandibular canine may be much of the distoincisal tooth structure (i.e., sometimes referred
indicated, however, if the lesion is more facial than lingual. he to as the “incisal canopy”) as possible to reduce the risk for sub-
mandibular restoration is often not visible at conversational distance sequent fracture. When possible (i.e., when the incisal enamel has
(Fig. 10.116). he outline form of the Class III amalgam preparation dentin support), it is best to leave the incisal margin in contact
may include only the proximal surface. A lingual dovetail may be with the adjacent tooth.
indicated if one existed previously or if additional retention is When preparing a gingival wall that is near the level of the
needed for a larger restoration. rubber dam or apical to it, it is beneicial to initially place a wedge
370 C HA P T E R 1 0 Clinical Technique for Amalgam Retoration

A B C D
• Fig. 10.117 Entry for Class III tooth preparation on maxillary canine. A, Bur position is perpendicular
to the enamel surface at the point of entry. B, Initial penetration through enamel is directed toward
cavitated, caries lesion. C, Initial entry should isolate the proximal enamel, while preserving as much of
the marginal ridge as possible. D, Initial cutting reveals the DEJ (arrow).

Facial
Axial wall
dentinal depths i
before preparing
cove and groove:
crown, 0.5-0.6 mm
root, 0.75-0.8 mm g1

Arrows depict 0.25 mm

depth direction g2 deep

• Fig. 10.118 Mesiodistal vertical section showing location, depth direc-

tion (arrows), and direction depth of the retention form in Class III tooth
preparations of different gingival depths. Incisal cove (i); gingival groove Lingual
(g1), enamel margin; gingival groove (g2), root-surface margin. Distance
from outer aspect of g2 groove to margin is approximately 0.3 mm; bur
head diameter is 0.5 mm; direction depth of groove is half this diameter
(or approximately 0.3 mm [0.25 mm]).
• Fig. 10.120 Transverse section of mandibular lateral incisor illustrating
that the lingual wall of a Class III tooth preparation may meet the axial wall
at an obtuse angle and that the axial wall is a uniform depth into dentin
and follows the faciolingual contour of the external tooth surface.

in the gingival embrasure to depress and protect soft tissue and

the rubber dam. As the bur is preparing the gingival wall, it may
lightly shave the wedge. A triangular (i.e., anatomic) wedge, rather
than a round wedge, is used for a deep gingival margin.
he initial tooth preparation is completed by using a No. 1 2
round bur to accentuate the axial line angles (Fig. 10.122A and
B), particularly the axiogingival angle. his facilitates the subsequent
placement of retention grooves and leaves the internal line angles
slightly rounded. Rounded internal preparation angles permit more
complete condensation of the amalgam. he No. 1 2 round bur
A B
also may be used to smooth any roughened, undermined enamel
• Fig. 10.119 Class III tooth preparation on maxillary canine. A, Round produced at the gingival and facial cavosurface margins (see Fig.
bur shaping the incisal area. The incisal angle remains. B, Initial shape of 10.122C). he incisal margin of the minimally extended preparation
the preparation accomplished with a round bur. is often not accessible to the larger round bur without damaging
 CHAPTER 10 Clinical Technique for Amalgam Retoration 371

A B
• Fig. 10.121 Distofacial (A) and incisal (B) views of the canine to show the curved proximal outline
necessary to preserve the distoincisal corner of the tooth. The incisal margin of this preparation example
is located slightly incisally of the proximal contact (but whenever possible, the margin may be in the
contact area).

A B C D
• Fig. 10.122 Reining proximal portion. A–C, A small, round bur is used to shape the preparation walls,
deine line angles, and initiate removal of any undermined enamel along the gingival and facial margins.
D, Tooth preparation completed, except for the inal inishing of the enamel margins and placement of
secondary retention.

(“marring”) the adjacent tooth (see Fig. 10.122D). Further inishing between the groove and the DEJ. he rotating bur is moved lingually
of the incisal margin is presented later. At this point the initial along the axiogingival line angle, with the angle of cutting generally
tooth preparation is completed. bisecting the angle between the gingival and axial walls. Ideally
the direction of the gingival groove is slightly more gingival than
Final Tooth Preparation axial (and the direction of an incisal [i.e., occlusal] groove would
Final tooth preparation involves removing any remaining soft be slightly more incisal [i.e., occlusal] than axial) (Fig. 10.123; see
dentin, protecting the pulp, developing secondary resistance and also Fig. 10.118).
retention forms, inishing external walls, and debridement (clean- Alternatively if less retention form is needed, two gingival coves
ing)/inspecting. Any remaining soft dentin on the axial wall is may be used as opposed to a continuous groove. One each may
removed by using a slowly revolving round bur (No. 2 or No. 4), be placed in the axiofaciogingival and axiogingivolingual point
appropriate spoon excavators, or both. (See Chapter 2 for the angles. he diameter of the 1 4 round bur is 0.5 mm, and the
management of soft dentin.) depth of the groove should be ~0.25 to 0.5 mm. Note the location
For the Class III amalgam restoration, resistance form against and depthwise direction of the groove, where the gingival wall
postrestorative fracture is provided by (1) cavosurface and amalgam remains in enamel (Fig. 10.124). When preparing a retention
margins of 90 degrees, (2) enamel walls supported by sound dentin, groove on the root surface (gingival wall in cementum or dentin),
(3) suicient bulk of amalgam, and (4) rounded preparation internal the angle of cutting is more gingival, resulting in the distance from
angles. he boxlike preparation form provides primary retention the gingival cavosurface margin to the groove being approximately
form. Secondary retention form is provided by a gingival groove, 0.3 mm (see Fig. 10.118). Careful technique is necessary in prepar-
an incisal cove, and sometimes a lingual dovetail. ing the gingival retention groove. If the dentin that supports gingival
he gingival retention groove is prepared by placing a No. 1 4 enamel is removed, enamel is subject to fracture. In addition, if
round bur (rotating at low speed) in the axiofaciogingival point the groove is placed only in the axial wall, no efective retention
angle. It is positioned in the dentin to maintain 0.2 mm of dentin form is developed and the risk of pulpal involvement is increased.
372 C HA P T E R 1 0 Clinical Technique for Amalgam Retoration

A B C
• Fig. 10.123 Preparing the gingival retention form. A, Position of No. 14 round bur in axiofaciogingival
point angle. B, Advancing the bur lingually to prepare the groove along the axiogingival line angle. (See
Fig. 10.118 regarding location, depth direction, and direction depth of groove.) C, Completed gingival
retention groove.

• Fig. 10.124 Completed Class III tooth preparation for amalgam

restoration.

B
• Fig. 10.126 Use of the palm-and-thumb grasp to place the incisal
retention cove. A, Hand position showing thumb rest. B, Handpiece posi-
tion for preparing the incisal retention.
A B
• Fig. 10.125 Preparing the incisal retention cove. A, Position of No. incisally (Fig. 10.126). his completes the typical Class III amalgam
1
4 round bur in the axioincisal point angle. B, Completed incisal cove. tooth preparation (see Fig. 10.124).
A lingual dovetail is not required in small or moderately sized
Class III amalgam restorations. It may be used in large preparations,
An incisal retention cove is prepared at the axiofacioincisal especially preparations with excessive incisal extension in which
point angle with a No. 1 4 round bur in dentin, being careful not additional retention form is needed. he dovetail may not be
to undermine enamel. It is directed similarly into the incisal point necessary (even in large preparations), however, if an incisal second-
angle and prepared to half the diameter of the bur (Fig. 10.125). ary retention form is possible (Fig. 10.127).
Undermining the incisal enamel should be avoided. For the maxillary If a lingual dovetail is needed, it is prepared only after initial
canine, the palm-and-thumb grasp may be used to direct the bur preparation of the proximal portion has been completed. Otherwise
 CHAPTER 10 Clinical Technique for Amalgam Retoration 373

A B C
• Fig. 10.127 Extensive Class III tooth preparation. A, Initial tooth preparation with No. 2 round bur.
B, Deining line angles and removing undermined enamel with No. 12 round bur. C, Placing the retention
groove using No. 14 round bur. Note the completed incisal cove.

A B C D

E F G H
• Fig. 10.128 Lingual dovetail providing additional retention for extensive amalgam restoration. A, Bur
position at correct depth and angulation to begin cutting. B, Initial cut in beginning dovetail. C, Bur moved
to most mesial extent of dovetail. D, If possible, cutting should not extend beyond the midlingual position.
E, Bur cutting gingival extension of the dovetail. F, Incisal and gingival extensions of the dovetail.
G, Completing the isthmus. The proximal and lingual portions are connected by the incisal and gingival
walls in smooth curves. H, Completed lingual dovetail.

the tooth structure needed for the isthmus between the proximal of the tooth. he No. 245 bur is positioned in the proximal portion
portion and the dovetail may be removed when the proximal at the correct depth and angulation and moved in a mesial direction
outline form is prepared. he lingual dovetail should be conservative, (Fig. 10.128A and B). he correct angulation places the long axis
generally not extending beyond the mesiodistal midpoint of the of the bur perpendicular to the lingual surface. he bur is moved
lingual surface; this varies according to the extent of the proximal to the point that corresponds to the most mesial extent of the
caries lesion. he depth of the axial wall of the dovetail should be dovetail (see Fig. 10.128C and D). he bur is then moved incisally
just inside the DEJ and should be parallel to the lingual surface and gingivally to create suicient incisogingival dimension to the
374 C HA P T E R 1 0 Clinical Technique for Amalgam Retoration

dovetail (approximately 2.5 mm) (see Fig. 10.128E and F). he

incisal and gingival walls of the isthmus are prepared in smooth
curves connecting the dovetail to the proximal outline form (see
Fig. 10.128G and H).
The gingival margin trimmer may be used to round the
axiopulpal line angle (i.e., the junction of the proximal and dovetail
preparation). his increases the strength of the restoration at the
junction of the proximal and lingual portions by providing bulk
and limiting stress concentration. he slight lingual convergence
of the dovetail’s external walls (prepared with the No. 245 bur)
usually provides a suicient retention form. Retention coves, one
in the incisal corner and one in the gingival corner (Fig. 10.129),
may be placed in the dovetail to enhance retention. he coves are
A B prepared with the No. 1 4 round bur or the No. 33 1 2 bur without
compromising the dentinal support of the lingual enamel. his
• Fig. 10.129 Ensuring retention in lingual dovetail (often optional). A,
preparation may require deepening of the axial wall. Unsupported
Position of No. 33 12 bur for cutting the retention cove. B, Preparation of
the cove should not remove the dentinal support of the lingual enamel
enamel is removed, the walls or margins are smoothed, and the
(arrow). cavosurface angles are reined, where indicated. he 8-3-22 hoe
is recommended for inishing minimally extended margins (Fig.
10.130). If the gingival margin is in enamel, correct marginal
coniguration (approximately 20 degrees gingival declination) is

No. 2 round

1/ round
4
A C
8-3-22

D E

B F G
• Fig. 10.130 Class III tooth preparation for amalgam restoration on the mandibular incisor. A, Entering
the tooth from the lingual approach. B, Finishing the facial, incisal, and lingual enamel margins with an
8-3-22 triple angle hoe. Note how the secondary cutting edge of the blade is used on the lingual enamel.
C, Placing incisal and gingival retention forms with No. 14 round bur. D, Dotted line indicates the outline
of the additional extension that is sometimes necessary for access in placing the incisal retention cove.
E, Position of a bi-beveled hatchet to place the incisal retention cove. F, The axial wall forms a convex
surface over the pulp. G, Completed tooth preparation. Note the gingival retention groove.
 CHAPTER 10 Clinical Technique for Amalgam Retoration 375

II preparations. When properly placed, conservative restorations

in incisors and canines are relatively inconspicuous (Fig. 10.134).
Fig. 10.135 illustrates a Class III amalgam restoration in a man-
dibular incisor.

Finishing and Polishing

Finishing and polishing of the Class III amalgam should follow
the approach presented in General Concepts Guiding Restoration
with Amalgam.

Clinical Technique for Cla V

Amalgam Retoration
Class V restorations are indicated to restore defects on the facial
• Fig. 10.131 Completed distolingual Class III tooth preparation for
or lingual cervical one third of any tooth. Class V amalgam restora-
amalgam.
tions may be especially technique sensitive because of location,
extent of the caries lesion, and limited access and visibility. Cervical
necessary to ensure full-length enamel rods forming the cavosurface caries lesions usually develop because of the chronic presence of
margin. All the walls of the preparation should meet the external an acidogenic bioilm located in the non–self-cleansing area just
tooth surface to form a right angle (i.e., butt joint) (Fig. 10.131; gingival to the height of contour. Patients with gingival recession
see also Fig. 10.124). he various steps involved in the preparation are predisposed to Class V root caries lesions because dentin is more
of the dovetail are shown in Fig. 10.132. susceptible to demineralization than enamel. Patients with a reduced
he completed tooth preparation should be cleaned of any salivary low caused by certain medical conditions (e.g., Sjögren’s
residual debris and inspected. Careful assessment should be made syndrome), medications, or head and neck radiation therapy are
to see that all of the caries lesion has been removed (as indicated), also predisposed to cervical and root caries lesions. hese patients
that the depth and retention are appropriate, and that cavosurface usually have less saliva to bufer the acids produced by oral bacteria.
margins provide for suicient amalgam bulk. Class V restorations may be used to treat both cervical and root
caries lesions. Incipient, smooth-surface enamel demineralization
appears as a chalky white line just occlusal or incisal to the crest
Retorative Technique for Cla III Amalgam of the marginal gingiva (usually on the facial surface) (Fig. 10.136).
Preparation hese areas often are overlooked in the oral examination unless
teeth are isolated with cotton rolls, free of debris, and dried gently
Desensitizer Placement with the air syringe. When the incipient cervical caries has not
A dentin desensitizer is placed on the prepared tooth structure per decalciied the enamel suiciently to result in cavitation (i.e., a
manufacturer instructions. Excess moisture is removed without break in the continuity of the surface), the lesion may be remineral-
desiccating the dentin. ized by appropriate techniques, including patient motivation toward
proper diet and hygiene. Occasionally an enamel surface that is
Matrix Placement only slightly cavitated may be treated successfully by smoothing
he wedged, rigid material–supported sectional matrix may be with sandpaper disks, polishing, and treating with a luoride varnish
used for the Class III amalgam restoration. It is essential to trim or iniltrated with a low viscosity resin in an attempt to prevent
the lingual portion of the sectional matrix material correctly to further demineralization, cavitation, and surgical management.
avoid covering the preparation and blocking access for insertion Prophylactic, preventive treatment alone will be inadequate if the
of the amalgam. Stainless steel matrix material is obtained, 8 mm caries lesion has progressed to decalcify and soften enamel to an
wide and 0.05 mm thick, which covers one third of the facial appreciable depth. In this instance, a Class V tooth preparation
surface and extends through the proximal to the lingual surface. and restoration is indicated, particularly if the caries lesion has
he lingual portion is trimmed at an angle that corresponds penetrated to the DEJ (Fig. 10.137A). When numerous cervical
approximately to the slope of the lingual surface of the tooth (Fig. lesions are present (see Fig. 10.137B), high caries activity is obvious.
10.133). he section of matrix is burnished on a resilient paper In addition to the restorative treatment, the patient should be
pad to create the desired proximal surface form. he sectional instructed and encouraged to implement an aggressive prevention
matrix is placed in position and wedged from the facial or lingual program to avoid subsequent development of additional caries
embrasure, whichever is greater. he facial and lingual portions of lesions. Class V amalgam restorations may be used anywhere in
the matrix are stabilized with a rigid material (see Fig. 10.132G). the mouth. As with Class III amalgam restorations, they generally
Precontoured metallic matrices may be used (instead of custom-made are reserved for nonesthetic areas, for areas where access and visibility
matrices) if the contour of the precontoured matrix coincides with are limited and where moisture control is diicult, such as areas
that of the proximal surface being restored. If the preparation is that are signiicantly deep gingivally. Because of limited access and
small and the matrix is suiciently rigid, additional rigid material visibility, many Class V restorations are diicult and present special
to support the matrix may not be required. problems during the preparation and restorative procedures.
Occasionally amalgam is preferred when the caries lesion extends
Condensation and Carving gingivally enough that a mucoperiosteal lap must be relected for
Insertion of the amalgam, initial carving, matrix removal, wedge adequate access and visibility (Fig. 10.138). Proper surgical technique
removal, and inal carving are similar to the techniques for Class must be followed, with special attention to complete debridement
376 C HA P T E R 1 0 Clinical Technique for Amalgam Retoration

A B C

D E F

G H I
• Fig. 10.132 Distolingual tooth preparation and restoration. A, Bur position for entry. B, Penetration
made through the lingual enamel to the caries lesion. C, Proximal portion completed, except for the
retention form. D, Preparing the dovetail. E, Completed preparation, except for the retention groove and
the coves. F, Bur position for the incisal cove in the dovetail. G, Rigid material–supported sectional matrix
ready for the insertion of amalgam. H, Carving completed and rubber dam removed. I, Polished
restoration.

A B C
• Fig. 10.133 Matrix strip design. A, Design required for rigid material–supported matrix for Class II
tooth preparations. B, Alteration necessary for Class III preparation on the maxillary canine. C, Alteration
necessary for the mandibular incisor. The strip material is cut to approximate the slope of the lingual
surface.
 CHAPTER 10 Clinical Technique for Amalgam Retoration 377

of amalgam particles before closure of the surgical site. Class V

amalgam restorations usually are contraindicated in esthetically
important areas because many patients object to metal restorations
that are visible (Fig. 10.139). Generally Class V amalgams placed
on the facial surface of mandibular canines, premolars, and molars
are not readily visible. Amalgams placed on maxillary premolars
and irst molars may be visible.
Amalgam may be used in the cervical areas of partial denture
abutment teeth because amalgam resists wear as clasps move over
• Fig. 10.134 Inconspicuous facial margin (arrow) of Class III amalgam the restoration. Contours prepared in the restoration for clasp
restoration on the maxillary canine. retentive areas may be achieved relatively easily and maintained
when an amalgam restoration is used.

Initial Procedures
Proper isolation prevents moisture contamination of the operating
site, enhances asepsis, and facilitates access and visibility. Moisture
in the form of saliva, gingival sulcular luid, or gingival hemorrhage
must be excluded during caries lesion removal, liner application,
and insertion and carving of amalgam. Moisture impairs visual
assessment, may contaminate the pulp during caries lesion removal
(especially with a pulpal exposure), and may negatively afect the
physical properties of the amalgam. he gingival margin of Class
V tooth preparations is often apical to the gingival crest. Such a
gingival margin necessitates use of appropriate rubber dam and
retainer, or displacement of the free gingiva with a retraction cord,
to protect it and to provide access. Isolation helps eliminate seepage
of sulcular fluid into the tooth preparation or restorative
materials.
Isolation objectives are met through local anesthesia and use
• Fig. 10.135 Class III amalgam restoration on the mandibular incisor
of (1) a cotton roll and a retraction cord or (2) a rubber dam and
(arrowhead).
a suitable cervical retainer (Fig. 10.140). Isolation with a cotton
roll and a retraction cord is satisfactory when properly performed
(Fig. 10.141). his type of isolation is practical and probably the
approach most often used. he retraction cord should be placed
in the sulcus before initial tooth preparation to reduce the possibility
of cutting instruments damaging the free gingiva. he cord should
produce a temporary, adequate, atraumatic lateral displacement
of the free gingiva. he cord may be treated with hemostatic
preparations containing aluminum chloride or ferrous sulfate.
Alternatively the cord may be treated with epinephrine; however,
caution must be used as epinephrine on abraded gingiva is absorbed
rapidly into the circulatory system and may cause an increase in
• Fig. 10.136 Incipient caries lesions of enamel appear as white spots.
The affected surface may be smooth (i.e., noncavitated). White spots are
blood pressure, elevated heart rate, and possible dysrhythmia. he
more visible when dried. (From Cobourne MT, DiBiase AT: Handbook of retraction cord may be braided, twisted, or woven. he diameter
orthodontics, Edinburgh, 2010, Mosby.) of the cord should be easily accommodated in the gingival sulcus.

A B
• Fig. 10.137 Cervical caries lesions. A, Cavitation involving enamel and dentin in several teeth.
B, Relatively high caries index is obvious when numerous cervical lesions are present. (From Perry DA,
Beemsterboer PL: Periodontology for the dental hygienist, ed 3, St. Louis, 2007, Saunders.)
378 C HA P T E R 1 0 Clinical Technique for Amalgam Retoration

A B C
• Fig. 10.138 Surgical access. A, Class V preparation requiring mucoperiosteal lap relection with a
releasing incision (arrowhead). B, Completed restoration with suture in place. C, Suture removed 1 week
after the procedure.

steps along the cord helps prevent dislodgment of previously inserted

cord (see Fig. 10.141). In addition, using a second instrument
stepping along behind the irst instrument may help prevent dislodg-
ment of cord. Additionally using the air syringe or cotton pellets
to reduce or absorb the sulcular luid in the cord already placed
is helpful during cord placement. he cord results in adequate
retraction (displacement) in a short time. he cord may be moistened
with the hemostatic solution before, during, or after placement if
slight hemorrhage is anticipated or observed. Alternatively the
cord may be used dry.
he cord usually remains in place during tooth preparation as
• Fig. 10.139 Patients may object to metal restorations that are visible well as insertion and initial carving of amalgam. While carving
during conversation. amalgam at the gingival margin, the presence of the cord may
cause diiculty in detection of the unprepared tooth surface apical
to the margin. his may limit proper carving, result in an over-
contour and marginal excess. In this instance, after carving gross
excess, the cord may be teased from the sulcus before the carving
is completed.

Tooth Preparation for Cla V

Amalgam Retoration
Proper outline form for Class V amalgam tooth preparations results
in extending the cavosurface margins to sound tooth structure
while maintaining a limited axial depth of 0.5 mm inside the DEJ
• Fig. 10.140 A rubber dam and a No. 212 retainer may be required to and 0.75 mm inside cementum (when on the root surface). he
isolate the caries lesion properly. outline form for the Class V amalgam tooth preparation is deter-
mined primarily by the location and size of the caries lesion or
old restorative material. Clinical judgment determines inal prepara-
If signiicant blanching of the free gingiva is observed (or if too tion outline, especially when the cavosurface margins approach or
much pressure has to be applied to place the cord), an oversized extend into areas of enamel decalciication. he operator must
cord may have been selected. If so, it should be exchanged for a observe the prepared enamel wall to evaluate the depth of the
cord of smaller diameter. An appropriate amount is cut to a length decalciied enamel and to determine if cavitation exists peripheral
6 mm longer than the gingival margin. Some operators prefer to to the wall. When no cavitation has occurred and when the
place the cord in a dappen dish, wet it with a drop of hemostatic decalciication does not extend appreciably into the enamel, exten-
solution, and blot it with gauze (5 × 5 cm) to remove excess liquid. sion of the outline form often should cease. In some cases, if all
A braided or woven cord is usually easier to use because it does decalciication were included in the outline form, the preparation
not unravel during placement. A larger cord may be inserted over would extend into the proximal cervical areas (if not circumfer-
the irst cord if the sulcus is large enough to accommodate two entially around the tooth). Such a preparation would be diicult
cords. A thin, blunt-edged instrument blade or the side of an and perhaps unrestorable. A full-coverage indirect restoration should
explorer tine may be used to gently insert the cord progressively be considered for teeth with extensive circumferential cervical
into place. A slight backward direction of the instrument as it decalciication (but only after caries risk has been reduced).
 CHAPTER 10 Clinical Technique for Amalgam Retoration 379

A B

C D
• Fig. 10.141 Use of the retraction cord for isolation of a Class V lesion. A, Preoperative view. B, Cord
placement initiated. C, Cord placement using a thin, lat-bladed instrument. D, Cord placement
completed.

A B
• Fig. 10.142 Starting the Class V tooth preparation. A, Bur positioned for entry into caries lesion.
B, The entry cut is the beginning of the outline form having a limited axial depth.

Initial Tooth Preparation changing of the bur orientation so as to accommodate the cervical
A Class V amalgam restoration is not used often in a mandibular mesiodistal and incisogingival (or occlusogingival) convexity of the
canine, but it is presented here for illustration. he same general tooth. he preparation is extended incisally, gingivally, mesially,
principles for tooth preparation apply for all other tooth locations. and distally until the cavosurface margins are positioned in sound
A tapered issure bur of suitable size (e.g., No. 271) is used to enter tooth structure such that an initial axial depth of 0.5 mm inside
the caries lesion (or existing restoration) to a limited initial axial the DEJ (or 0.75 mm if on the root surface) is established. When
depth of 0.5 mm inside the DEJ (Fig. 10.142). his depth is usually extending mesially and distally, it may be necessary to protect the
1 to 1.25 mm total axial depth, depending on the incisogingival rubber dam from the bur by placing a lat-bladed instrument over
(i.e., occlusogingival) location. he enamel of the incisal (occlusal) the dam (Fig. 10.144). Because the axial wall follows the mesiodistal
external wall of the preparation is considerably thicker than the and incisogingival (or occlusogingival) contours of the facial surface
cervical. If the preparation is on the root surface, however, the initial of the tooth, it usually is convex in both directions (Fig. 10.145).
axial depth is approximately 0.75 mm. he end of the bur at the In addition, the axial wall usually is slightly deeper at the incisal
initial depth may be in sound dentin, in soft dentin, or in old wall, where more enamel (i.e., approximately 1–1.25 mm in depth)
restorative material. he edge of the bur end may be used to penetrate is present than at the gingival wall, where little or no enamel (i.e.,
the area; this is more eicient than using the lat end of the bur, approximately 0.75–1 mm in depth) may be present. A depth of
reducing the possibility of the bur’s tendency to “crawl” (i.e., move 0.5 mm inside the DEJ permits placement of necessary retention
laterally instead of cut axially) on the external surface. When the grooves without undermining enamel. his subtle diference in
entry is made, the bur orientation is adjusted to ensure that all depth serves also to increase the thickness of the remaining dentin
external walls are perpendicular to the external tooth surface (i.e., (between the axial wall and the pulp) in the gingival aspect of the
parallel to the enamel rods) (Fig. 10.143). his requires frequent preparation to aid in protecting the pulp.
380 C HA P T E R 1 0 Clinical Technique for Amalgam Retoration

A B

C D
• Fig. 10.143 When extending incisally (A), gingivally (B), mesially (C), and distally (D), the bur is posi-
tioned to prepare these walls perpendicular to the external tooth surface.

the gingivoaxial line angle (see Fig. 10.145). he handpiece is

positioned so that the No. 1 4 round bur is directed generally to
bisect the angle formed at the junction of the axial wall and the
incisal (i.e., occlusal) wall. Ideally the direction of the incisal (i.e.,
occlusal) groove is slightly more incisal (i.e., occlusal) than axial,
and the direction of the gingival groove is slightly more gingival
than axial. Alternatively, four retention coves may be prepared,
one in each of the four axial point angles of the preparation (Fig.
10.146).
Using four coves instead of two full-length grooves conserves
• Fig. 10.144 The lat-bladed instrument protects the rubber dam from the dentin near the pulp, reducing the possibility of a mechanical
the bur. pulp exposure. he depth of the grooves (or coves) should be
approximately 0.25 to 0.5 mm. It is important that the retention
grooves be adequate because they provide the only retention form
Alternatively, an appropriate carbide bur (usually No. 2 or No. to the preparation. Regardless, the grooves should not remove
4) may be used for the initial tooth preparation. Round burs are dentin immediately supporting enamel. In a large Class V amalgam
indicated in areas inaccessible to a issure bur, which must be preparation, extending the retention groove circumferentially around
oriented perpendicular to the tooth surface. If needed, smaller all the internal line angles of the tooth preparation may enhance
round burs may also be used to deine the internal angles in these the retention form.
preparations, enhancing proper placement of the retention grooves. If access is inadequate for use of the No. 1 4 round bur, an
angle-former chisel may be used to prepare the retention form.
Final Tooth Preparation Additionally, a No. 33 1 2 bur may be used. Both methods result
Final tooth preparation involves the removal of any remaining soft in retention grooves that are angular, but positioned in the same
dentin, pulp protection, retention form, the inishing of external location and approximately to the same depth as when the No.
walls, and cleaning/inspecting. Speciically any remaining soft axial 1 round bur is used. he rounded retention form created with
4
wall dentin is removed (as indicated) with a No. 2 or No. 4 round the No. 1 4 round bur is generally preferred, however, because
bur. Any old restorative material remaining (including base and amalgam is able to be condensed into rounded areas more readily
liner) may be left if (1) no evidence of recurrent caries exists, (2) than into sharp areas, resulting in better adaptation of amalgam
the periphery of the base and liner is intact, and (3) the tooth is into the retention grooves. If necessary, suitable hand instruments
asymptomatic. With proper outline form, the axial line angles are (e.g., chisels, margin trimmers) are used to plane the enamel margins,
already in sound dentin. If needed, an appropriate liner or base verifying soundness and 90-degree cavosurface angles. Finally the
is applied. preparation is cleaned of debris and inspected for completeness.
Because the mesial, distal, gingival, and incisal walls of the
tooth preparation are perpendicular to the external tooth surface, Large Preparations That Include Line Angles
they usually diverge. Consequently this form provides no inherent A caries lesion on the facial (or lingual) surface may extend beyond
retention, and retention form must be provided to retain the the line angles of the tooth. Maxillary molars, particularly the
amalgam. A No. 1 4 round bur is used to prepare two retention second molars, are most commonly afected by these extensive
grooves, one along the incisoaxial line angle and the other along defects (Fig. 10.147A). In this example, if the remainder of the
 CHAPTER 10 Clinical Technique for Amalgam Retoration 381

A B

C D E

F G
• Fig. 10.145 Retention form. A, A No. 14 round bur positioned to prepare the gingival retention groove.
B, Gingival retention groove (arrow) prepared along the gingivoaxial line angle generally to bisect the angle
formed by the gingival and axial walls. Ideally the direction of preparation is slightly more gingival than
pulpal. An incisal retention groove is prepared along the incisoaxial line angle and directed similarly. C and
D, A groove is placed with a No. 14 round bur along the gingivoaxial and incisoaxial line angles 0.2 mm
inside the DEJ and ~0.25 – 0.5 mm deep. Note the slight pulpal inclination of the shank of the No. 14
round bur. E, Facial view. F, Incisogingival section. Grooves depthwise are directed mostly incisally (gin-
givally) and slightly pulpally. G, Mesiodistal section.

distal surface is sound and the distal caries lesion is accessible Preparing the facial portion irst provides better access and visibility
facially, the facial restoration should extend around the line angle. to the distal portion. Occasionally hand instruments may be useful
his prevents the need for a Class II proximal restoration to restore for completing the distal half of the preparation when space for
the distal surface. However, the operator should strive not to the handpiece is limited (see Fig. 10.147D–F).
overextend the occlusal wall of the distal surface preserving as Grooves placed along the entire length of the occlusoaxial and
much sound tooth structure as possible to support the distal marginal gingivoaxial line angles help ensure retention of the restoration.
ridge. As much of the preparation as possible should be completed he No. 1 4 round bur is used as previously described to prepare
with a issure bur. A round bur approximately the same diameter the retention grooves. A gingival margin trimmer or a 7-85- 2 1 2
as the issure bur is then used to initiate the distal portion of the -6 angle-former chisel may be used in the distal half of the prepara-
preparation (see Fig. 10.147B and C). Smaller round burs should tion to provide retention form when access for the handpiece is
be used to accentuate the internal line angles of the distal portion. limited (see Fig. 10.147G and H).
382 C HA P T E R 1 0 Clinical Technique for Amalgam Retoration

1 mm 0.2 mm
B

0.25 mm
0.75 mm
0.25 - 0.3 mm Recommended
A C D four-cove retention

• Fig. 10.146 A–C, Extended Class V tooth preparation (A) with the axial wall contoured parallel to the
DEJ mesiodistally (B) and incisogingivally (C). The axial wall pulpal depth is 1 mm in the crown and
0.75 mm in the root. In addition, note location and direction depth (~0.25 – 0.5 mm) of the retention
grooves and the dimension of the gingival wall (0.25 mm) from the root surface to the retention groove.
D, Large Class V preparation with retention coves prepared in the four axial point angles.

A B C

D E F

G H I
• Fig. 10.147 Tooth preparation on a maxillary molar. A, Caries lesion extending around distofacial
corner of the tooth. B and C, Distal extension is accomplished with round bur. D–F, A gingival margin
trimmer may be useful in completing the distal half of the preparation when handpiece access is limited.
G, A gingival margin trimmer may be used to provide the retention grooves. H, An angle-former chisel
may be used to prepare the retention grooves in the distal portion of the preparation. I, Completed tooth
preparation.

Because of the proximity of the coronoid process, access to the structure between the two restorations (Fig. 10.149). In this
facial surfaces of maxillary molars, particularly the second molars, illustration the previously placed amalgam serves as the distal wall
is often limited. Having the patient partially close and shift the of the preparation. When proper treatment requires Class II and
mandible toward the tooth being restored improves access and V amalgam restorations on the same tooth, the Class II preparation
visibility (Fig. 10.148). and restoration is completed before initiating the Class V restoration.
If the Class V outline form approaches an existing proximal If the Class V restoration was accomplished irst, it might be
restoration, it is better to extend slightly into the bulk of the damaged by the matrix band and wedge needed for the Class II
proximal restoration rather than to leave a thin section of the tooth restoration.
 CHAPTER 10 Clinical Technique for Amalgam Retoration 383

Matrix

• Fig. 10.148 The mandible shifted laterally for improved access and
visibility. Wedges

• Fig. 10.150 Application of the matrix to conine amalgam in the mesial

and distal extensions of the preparation.

must be trimmed to conform to the circumferential contour (level)

of the base of the gingival sulcus to prevent soft tissue damage.
Rather than using two short pieces, the operator may use a longer
• Fig. 10.149 When a Class V outline form closely approaches an exist- length that is passed through one proximal contact, extended around
ing restoration, the preparation should be extended to remove the remain- the lingual surface, and passed through the other contact, forming
ing thin enamel wall to achieve adjoining restorations. a U-shaped matrix. Trimming the gingival edge to conform to the
interproximal soft tissue anatomy usually is more diicult with
one matrix strip than when two strips are used.
he preparation should then be cleaned, carefully inspected as A conventional Tolemire band and retainer may be used with
indicated in General Concepts Guiding Preparation for Amalgam a window cut into the band, with a high-speed handpiece bur, to
Restorations, and any inal modiications completed. allow access to the preparation for condensation (Fig. 10.151).
Alternatively, the tooth may be prepared and restored in sections
without using a matrix. Each successive section of the preparation
Retorative Technique for Cla V should be extended slightly into the previously condensed portion
Amalgam Preparation to ensure caries lesion removal.

Desensitizer Placement Insertion and Carving of the Amalgam

A dentin desensitizer is placed over the prepared tooth structure he amalgam carrier is used to insert the mixed amalgam into the
per manufacturer instructions. Excess moisture is removed without preparation in small increments (Fig. 10.152A). Amalgam is
desiccating the dentin. condensed into the retention areas irst by using an appropriate
condenser (see Fig. 10.152B). Amalgam is then condensed against
Matrix Placement the mesial and distal walls of the preparation (see Fig. 10.152C).
Most Class V amalgam restorations are accomplished without the Finally a suicient bulk of amalgam is placed in the central portion
use of any type of matrix. he most diicult condensation occurs to allow for carving the correct contour (see Fig. 10.152D). As
in a tooth preparation with an axial wall that is convex mesiodistally. the surface of the restoration becomes more convex, condensation
Two alternative methods for insertion may be used. he preferred becomes increasingly diicult. It is important to guard against the
method is the application of a matrix that conines amalgam in “land sliding” of amalgam during overpacking. A large condenser
the mesial and distal portions of the preparation (Fig. 10.150). or lat-bladed instrument held against amalgam may help resist
Short lengths of stainless steel matrix material, one each for the pressure applied elsewhere on the restoration (Fig. 10.153).
mesial and distal surfaces, are passed through the proximal contacts, Carving may begin immediately after the insertion of amalgam
carefully guided into the gingival sulcus, and wedged. he strips (Fig. 10.154). All carving should be done using the side of the
must be wide enough to extend occlusally through the respective explorer tine or a Hollenback No. 3 carver held parallel to the
proximal contacts and long enough to extend slightly past the margins. he side of the carving instrument always should rest on
facial line angles. he strip usually requires rigid material support the unprepared tooth surface adjacent to the prepared cavosurface
for stability. he strips ofer resistance against condensing the mesial margin; this prevents overcarving or submargination of the restora-
and distal portions, which provides support for condensing the tion. he carving procedure is begun by removing excess amalgam
center of the restoration. he gingival edge of the steel strip often to expose the incisal (or occlusal) margin. Removal of excess material
384 C HA P T E R 1 0 Clinical Technique for Amalgam Retoration

A B
• Fig. 10.151 Customized matrix band used to restore an area of proximal root caries. A, Conventional
Toflemire matrix with window cut into the band using a high-speed bur to allow access for condensation.
B, Matrix in place around the tooth, allowing lingual access to preparation.

A B

C D
• Fig. 10.152 Inserting amalgam. A, Place amalgam into the preparation in small increments. B, Con-
dense irst into the retention grooves with a small condenser. C, Condense against the mesial and distal
walls. D, Overill and provide suficient bulk to allow for carving.

gingival inlammation and increased risk of secondary caries from

bioilm accumulation.
In some instances it is appropriate to change facial contours
because of altered soft tissue levels (e.g., cervical lesions in peri-
odontally treated patients). Facial contours may be increased (or
relocated) only enough to prevent food impaction into the gingival
sulcus and to provide access for the patient to clean the area.
Overcontouring must be avoided as it results in reduced stimulation
and cleansing of the gingiva during mastication.
When a rubber dam and the No. 212 cervical retainer have
• Fig. 10.153 Use a large condenser or a lat-bladed instrument to offer been used for isolation, the retainer is removed using care to open
resistance to condensation pressure applied elsewhere on the the jaws of the retainer wide enough to prevent damage to the
restoration. surface of the restoration. he rubber dam is removed and the
area is examined carefully to ensure that no amalgam particles
remain in the sulcus.
continues until the mesial and distal margins are exposed. Finally, When a retraction cord is used for isolation, it may interfere
material excess at the gingival margin is carved away. Carving the with carving any excess amalgam at the gingival margin. If so,
marginal areas should result in developing the desired convex removal of the gross excess of amalgam is followed by careful removal
contours in the completed restoration. Improper use of the carving of the cord, followed by completion of the carving along the margin.
instruments results in a poorly contoured restoration. Note in Fig.
10.20 how carving instruments are positioned to provide the desired Finishing and Polishing of the Amalgam
contours. No amalgam excess should remain at the margins because If carving procedures were performed correctly, no inishing of
amalgam may break away, creating a defect at the margin, or cause the restoration should be required. A slightly moistened cotton
 CHAPTER 10 Clinical Technique for Amalgam Retoration 385

A B

C D
• Fig. 10.154 Carving and contouring the restoration. A, Begin the carving procedure by removing any
excess and locating the incisal margin. B and C, An explorer may be used to remove the excess and
locate the mesial and distal margins. D, Remove the excess and locate the gingival margin.

Clinical Technique for Cla VI

Amalgam Retoration
he Class VI tooth preparation is used to restore the incisal edge
of anterior teeth or the cusp tip regions of posterior teeth (see Fig.
10.26C). Such tooth preparations are frequently indicated where
attrition (loss of tooth substance from the occluding of food,
abrasives, and opposing teeth) has removed enamel to expose the
underlying dentin on those areas (Fig. 10.158). When the softer
• Fig. 10.155 Incorrect use of a pointed stone at the gingival margin
dentin is exposed, it wears faster than the surrounding enamel,
results in the removal of cementum, notching of the tooth structure gingival
to the margin, or both.
resulting in “cupped-out” areas of the cusp tips. Intrinsic or extrinsic
erosion also may be contributing to the excessive loss of tooth
structure. Diagnostic steps, to identify the etiology of the tooth
structure loss, are indicated and may involve referral for evaluation
pellet held in cotton pliers may be used to further smooth the of potential gastroesophageal relux disease. As the dentin support
carved restoration. Additional inishing and polishing of amalgam is lost, enamel begins to fracture away and more dentin is exposed,
restorations may be necessary, however, to correct a marginal which often causes sensitivity. Sensitivity to hot and cold is a
discrepancy or to improve contour. Care is required when using frequent complaint with Class VI lesions, and some patients are
stones or any rotating cutting instruments on margins positioned bothered by food impaction in deeper depressions. Enamel edges
below the CEJ because of the possibility of removing cementum, may become jagged and sharp to the tongue, lips, or cheek. Lip,
notching the tooth structure gingival to the margin, or both (Fig. tongue, or cheek biting is occasionally a complaint. Rounding and
10.155). Fig. 10.156 illustrates reshaping a rubber abrasive point smoothing such incisoaxial (or occlusoaxial) edges is an excellent
to allow optimal access to the gingival portion of a Class V amalgam service to the patient. Early recognition and restoration of these
restoration. A rubber abrasive cup may be preferred for inishing lesions is recommended to limit the loss of dentin and the subse-
convex surfaces, like Class V restorations, if used carefully. quent loss of enamel supported by this dentin.
One measure of clinical success of cervical amalgam restorations he Class VI tooth preparation may be indicated to restore the
is the length of time the restoration serves without failing (Fig. hypoplastic pit occasionally found on cusp tips (Fig. 10.159). Such
10.157). Properly placed Class V amalgams have the potential to developmental faults are vulnerable to caries lesion formation,
be clinically acceptable for many years. Some cervical amalgam especially in high-risk patients, and should be restored as soon as
restorations show evidence of failure, however, even after a short they are detected.
period. Inattention to tooth preparation principles, improper Amalgam may be selected for posterior Class VI preparations
manipulation of the restorative material, and moisture contamina- because of its wear resistance and longevity. Moisture control for
tion contribute to early failure. Extended service life of the restora- Class VI restorations is usually achieved with cotton roll isolation.
tion depends on the operator’s care in following accepted treatment Class VI amalgam preparations may be accomplished with a small
techniques and proper care by the patient. Any additional inishing tapered issure bur (e.g., No. 169 L or 271) and involves extension
and polishing of the Class V amalgam should follow the approach to place the cavosurface margin on enamel that has sound dentin
presented in General Concepts Guiding Restoration with Amalgam. support (see Fig. 10.158B). he preparation walls may need to
386 C HA P T E R 1 0 Clinical Technique for Amalgam Retoration

A B C
• Fig. 10.156 Reshaping a rubber abrasive point against a mounted carborundum disk.

A B C
• Fig. 10.157 A, Six-year-old cervical amalgam restorations. B, After 16 years, some abrasion and
erosion are evident at the gingival margin of the lateral incisor and canine restorations. C, Twenty-year-old
cervical amalgam restorations.

A B
• Fig. 10.158 Class VI preparation. A, Exposed dentin on the mesiofa-
cial cusp. B, Tooth preparation necessary to restore the involved area.

• Fig. 10.159 Class VI lesions. Carious cusp tip fault on the irst pre-
diverge occlusally to ensure a 90-degree cavosurface margin. A molar (a). Noncarious fault on the second premolar (b).
depth of 1.5 mm is suicient to provide bulk of material for
strength. Retention of the restoration is ensured by the creation
of small undercuts along the internal line angles similar to other dentin. Teeth with excessive wear may require indirect restorations
areas where secondary retention is indicated. Conservative tooth or, at least, eforts to limit further loss of tooth structure.
preparation is particularly important with Class VI preparations
because it is easy to undermine the enamel on incisal edges and
cusp tips. he preparation should be cleaned, carefully inspected Clinical Technique for Complex
as indicated in General Concepts Guiding Preparation for Amalgam
Restorations, and any inal modiications completed. Insertion, Amalgam Retoration
carving, inishing, and polishing are similar to procedures described
in General Concepts Guiding Restoration with Amalgam.
Indication
Some older patients have excessive occlusal wear of most of Complex posterior restorations are indicated when tooth structure
their teeth in the form of large concave areas with much exposed is missing due to cusp fracture, severe caries lesion development,
 CHAPTER 10 Clinical Technique for Amalgam Retoration 387

or when replacement of existing restorative material is necessary. pins provide additional resistance and retention form to the tooth
Complex amalgam preparations should be considered when large when remaining vertical walls are inadequate.
amounts of tooth structure are missing, when one or more cusps
need to be covered, and when increased resistance and retention Status and Prognosis of the Tooth
forms are needed (Fig. 10.160).121 Complex amalgams may be A tooth with a severe caries lesion that may require endodontic
used as (1) deinitive (inal) restorations, (2) foundations, (3) control therapy or crown lengthening or that has an uncertain periodontal
restorations in teeth that have a questionable pulpal or periodontal prognosis often is treated initially with a control restoration. A
prognosis, or (4) control restorations in teeth with acute or severe control restoration helps (1) protect the pulp from the oral cavity
caries lesions. When determining the appropriateness of a complex (i.e., luids, thermal stresses, pH changes, bacteria), (2) provide
amalgam restoration, the factors discussed in the following sections an anatomic contour that is consistent with gingival health, (3)
must be considered. facilitate control of acidogenic bioilm and resultant caries risk,
and (4) provide some resistance against tooth fracture (or propaga-
Resistance and Retention Forms tion of an existing fracture). (See Chapter 2 for caries-control
In a tooth with a severe caries lesion or existing restorative material, rationale and techniques.)
any undermined enamel or weak tooth structure subject to fracture he status and prognosis of the tooth determine the size, number,
must be removed and replaced. Usually a weakened tooth is best and placement of retention features. Larger restorations generally
restored with a properly designed indirect (usually cast) restoration require more retention. he size, number, and location of retention
that prevents tooth fracture caused by mastication forces (see Online features demand greater care in smaller teeth. Carelessness may
Chapter 18). In selected cases, amalgam preparations that improve increase the risk of pulpal irritation or exposure.
the resistance form of a tooth may be designed (Fig. 10.161).
When conventional retention features are not adequate because Role of the Tooth in Overall Treatment Plan
of insuicient remaining tooth structure, the retention form may he restorative treatment choice for a tooth is inluenced by its
be enhanced by using auxiliary features such as slots and pins. he role in the overall treatment plan. Although complex amalgam
type of retention features needed depend on the amount of tooth restorations are used occasionally as an alternative to indirect restora-
structure remaining and the tooth being restored. As more tooth tions, particularly due to cost savings, they often are used as
structure is lost, more auxiliary retention is required. Slots and foundations for full-coverage restorations. Abutment teeth for ixed
prostheses may use a complex restoration as a foundation (Fig.
10.162). Extensive caries or previous restorations on abutment

• Fig. 10.160 Mesioocclusodistolingual (MODL) complex amalgam • Fig. 10.162 Mesioocclusodistofacial (MODF) amalgam foundation for
tooth No. 3. abutment tooth No. 15 in preparation for a 3 unit ixed partial denture.

A B
• Fig. 10.161 Maxillary second premolar weakened by an extensive caries lesion and by the small
fracture line extending mesiodistally on the center of the excavated dentinal wall. A, Minikin pins placed
in the gingival loor improve resistance form after amalgam has been placed. B, Restorations polished.
388 C HA P T E R 1 0 Clinical Technique for Amalgam Retoration

Reduced Cost
he complex amalgam restoration may be utilized to reinforce and
stabilize compromised posterior teeth at a much reduced cost to
the patient. It may serve as a deinitive inal restoration or an
intermediate-term restoration with a long-term goal of indirect,
more costly restoration and protection of the tooth.

Diadvantage
Tooth Anatomy
• Fig. 10.163 Mesioocclusodistolingual (MODL) complex amalgam Proper contours and occlusal contacts and anatomy are sometimes
tooth #19. diicult to achieve with large, complex restorations.

teeth for removable prostheses generally indicate an indirect restora- Resistance Form
tion for the resistance and retention forms and for development Resistance form is more diicult to develop with a complex amalgam
of external surface contours for retention of the prosthesis. A tooth as compared to the preparation of a tooth for a cusp-covering
may be treated with a complex direct restoration if adequate onlay (skirting axial line angles of the tooth [see Online Chapter
resistance and retention forms are provided. For patients with 18]) or a full crown. he complex amalgam restoration does not
periodontal and orthodontic problems, the complex restoration protect the tooth from fracture as efectively as a full-coverage
may be the restoration of choice until the inal phase of treatment, indirect restoration.
when indirect restorations may be preferred.
Occlusion and Economics Tooth Preparation for Complex
Complex amalgam restorations are sometimes indicated as interim Amalgam Retoration
restorations for teeth that require elaborate occlusal alterations, In this section various types of Complex Amalgam preparation
ranging from vertical dimension changes to correcting occlusal procedures are discussed before the restoration technique is pre-
plane discrepancies. When cost of indirect restorations is a major sented. Also the word “vertical” is used to describe tooth preparation
factor for the patient, the complex direct amalgam restoration may walls and other preparation aspects that are approximately parallel
be an appropriate treatment option, provided that adequate to the long axis of the tooth. he word “horizontal” is used to
resistance and retention forms are included (Fig. 10.163).122,123 describe the walls and other aspects that are approximately per-
pendicular to the long axis of the tooth. Every efort should be
Age and Health of Patient made to protect the pulp as early as possible when accomplishing
For some older patients and/or those who are debilitated, complex the procedures associated with complex amalgam restorations.
amalgam restoration may be the treatment preferred over the more
expensive and time-consuming indirect restoration. Preparation for Cusp Coverage Complex Amalgams
General concepts of initial tooth preparation presented in earlier
sections apply to the complex amalgam preparations described
Contraindication here. When a caries lesion is extensive with resultant loss of dentin
he complex amalgam restoration may be contraindicated if the necessary to support occlusally loaded areas of the tooth, reduction
tooth cannot be restored properly with direct restoration because of one or more of the cusps followed by coverage with amalgam
of anatomic or functional considerations (or both). he complex may be indicated. When the facial or lingual extension exceeds
amalgam restoration also may be contraindicated if the area to be two thirds the distance from a primary issure toward the cusp tip
restored has esthetic importance for the patient. (or when the faciolingual extension of the occlusal preparation
exceeds two thirds the distance between the facial and lingual cusp
Advantage tips), reduction of the cusp for coverage with amalgam usually is
required for the development of adequate resistance form (Fig.
Conservation of Tooth Structure 10.164A; see also Fig. 4.13). For cusps prone to fracture, coverage
he preparation for a complex amalgam restoration is usually more reduces the risk of fracture and extends the life of the restora-
conservative than the preparation for an indirect restoration. tion.125,126 Complex amalgam restorations that cover one or more
cusps have documented longevity of 72% after 15 years.123,127
Appointment Time he operator uses the bur to reduce the cusp, following the
he complex restoration may be completed in one appointment. mesiodistal inclines of the cusp; this results in a uniform reduction
An indirect restoration generally requires at least two appointments (see Fig. 10.164B–E). If only one of two facial (or lingual) cusps
unless it is done using a chairside computer-assisted design/ is to be covered, the cusp reduction should extend slightly beyond
computer-assisted machining (CAD/CAM) system. the facial (or lingual) groove area, provide the correct amount of
tooth structure removal, and meet the adjacent, unreduced cusp
Resistance and Retention Forms to create a 90-degree cavosurface margin. his approach results in
Amalgam restorations with cusp coverage signiicantly increase the adequate thickness and edge strength of the amalgam (see Fig.
fracture resistance of weakened teeth compared with amalgam 10.164F and G). Cusp reduction and coverage reduce the amount
restorations without cusp coverage.124 Resistance and retention of vertical preparation wall height and increase the need for the
forms may be signiicantly increased by the use of slots and pins use of secondary retention features (Fig. 10.165). An increased
(discussed in subsequent sections). retention form may be provided by proximal box retention grooves
 CHAPTER 10 Clinical Technique for Amalgam Retoration 389

A B

C D E

F G
• Fig. 10.164 Covering the cusp with amalgam. A, Comparison of the mesial aspects of normally
extended (left) and extensive (right) mesioocclusodistal tooth preparation. The resistance form of the
mesiolingual cusp with extensive preparation is compromised and cusp coverage with amalgam is indi-
cated. B, Preparing depth cuts. C, Depth cuts prepared. D, Reducing the cusp. E, Cusp reduced. F and
G, Final restoration.

visibility for subsequent steps. If the cusp to be reduced is located

at the correct occlusal height before preparation, depth cuts should
be made on the remaining occlusal surface of each cusp to be
covered, using the side of a carbide issure bur or a suitable diamond
instrument (see Fig. 10.164B). he depth cuts should be a minimum
of 2 mm for functional cusps and 1.5 mm for nonfunctional cusps.126
hese dimensions provide adequate strength for amalgam by prevent-
ing lexure of the restoration during loading. To reduce the cusp,
the dentist orients the bur parallel to the cuspal incline (lingual
incline for facial cusp reductions and facial inclines for lingual cusp
reduction) and makes several depth cuts in the cusp (to a depth of
• Fig. 10.165 A retention groove is associated with the remaining verti- 1.5 or 2 mm as indicated). he depth cuts provide guides for the
cal wall of a cusp requiring reduction. correct amount of cusp reduction. Without depth cuts, after the
beginning reduction of the cusp, the operator may no longer know
how much more reduction is necessary. When using the restoration
but may require the use of slots and/or pins (as described in to correct an occlusal relationship, if the unreduced cusp height is
subsequent sections). If indicated, cusp reduction and coverage located at less than the correct occlusal height, the depth cuts may
increase the resistance form of the tooth.123,128 be less. Likewise, if the unreduced cusp height is located higher
Reduction of the unsupported cusp should be accomplished than the correct occlusal height, the depth cuts may be deeper. he
during the initial tooth preparation because it improves access and goal is to ensure that the inal restoration has restored cusps with
390 C HA P T E R 1 0 Clinical Technique for Amalgam Retoration

a minimal thickness of 2 mm of amalgam for functional cusps and cusp is accomplished (if necessary) to include weak or carious
1.5 mm of amalgam for nonfunctional cusps (see Fig. 10.164C), tooth structure or existing restorative material. he lingual groove
while developing an appropriate occlusal relationship. Using the may be extended arbitrarily to increase the retention form (see
depth cuts as a guide, the reduction is completed to provide for a Fig. 10.167B and C). When possible, opposing vertical walls should
uniform reduction of tooth structure (see Fig. 10.164D). he occlusal be formed to converge occlusally, to enhance the primary retention
contour of the reduced cusp should be similar to the normal contour form (see Fig. 10.167C and D). he pulpal and gingival walls
of the unreduced cusp. Any sharp internal corners of the tooth should be relatively lat and perpendicular to the long axis of the
preparation formed at the junction of prepared surfaces should be tooth. Secondary retention features may be indicated when the
rounded to reduce stress concentration in the amalgam and improve divergence of proximal walls results in limited primary retention
its resistance to fracture from occlusal forces (see Fig. 10.164E). form (see Fig. 10.167D). Mesial extension of the preparation into
When reducing only one of two facial or lingual cusps, the cusp the mesiolingual cusp should be enough to allow placement of
reduction should be extended just past the facial or lingual groove, the distooblique and lingual groove within the amalgam restoration
creating a vertical wall against the adjacent unreduced cusp. Fig. (see Fig. 10.167E).
10.164F and G illustrate a inal restoration.
Mandibular First Molar
Mandibular First Premolar Reducing the distal cusp is an alternative to extending the entire
he lingual cusp of the mandibular irst premolar may need to be distofacial wall when the occlusal margin crosses the cuspal eminence
reduced for coverage with amalgam if the lingual margin of the (Fig. 10.168A; compare with Fig. 10.83). A minimal reduction
occlusal step extends more than two thirds the distance from the
central issure to the cuspal eminence (Fig. 10.166). Special attention
is given to such cusp reduction because retention is severely
diminished when the cusp is overreduced resulting in elimination
of the lingual wall of the occlusal portion. Depth cuts of 1.5 mm
aid the operator in establishing the correct amount of cusp reduction
and in conserving a small portion of the lingual wall in the occlusal
step. It is acceptable when restoring diminutive nonfunctional
cusps, such as the lingual cusp of a mandibular irst premolar, to
reduce the cusp only 0.5 to 1 mm and restore the cusp to achieve
an amalgam thickness of 1.5 mm. his procedure conserves more
of the lingual wall of the isthmus for added retention form.

Maxillary First Molar

he procedure for reducing the distolingual cusp of a maxillary
irst molar for coverage is illustrated in Fig. 10.167. Extending • Fig. 10.166 Mandibular irst premolar with the lingual cusp reduced
the facial or lingual wall of a proximal box to include the entire for coverage with amalgam.

A B C D E
• Fig. 10.167 Reduction of the distolingual cusp of the maxillary molar. A, Cutting a depth gauge groove
with the side of the bur. B, Completed depth gauge groove. C and D, Completed cusp reduction.
E, Distoocclusolingual complex amalgam.

A B
• Fig. 10.168 Mandibular irst molar. A, Reduction of the distal cusp is indicated when the occlusal
margin crosses the cuspal eminence. B, Distofacial view of the distal cusp shown in A before reduction
for coverage (left); the distal cusp after reduction (right). A reduction of 2 mm is necessary to provide for
minimal 2-mm thickness of amalgam.
 CHAPTER 10 Clinical Technique for Amalgam Retoration 391

0.8 mm
1.0 mm
1.0 mm

Dentin slot

Coves Coves

A B
• Fig. 10.169 Slots. A and B, With a No. 330 bur, dentinal slots are prepared approximately 1 mm
deep and 0.5 to 1 mm inside the DEJ.

of 2 mm will allow a 2-mm thickness of amalgam over the reduced

cusp (see Fig. 10.168B). he cusp reduction should result in a
butt joint between the tooth structure and amalgam. When possible,
reducing and covering the distal cusp is more desirable than
extending the distofacial proximal margin because this conserves
tooth structure of the functional cusp, and the remaining portion
of the cusp helps in applying the matrix for the development of Cove
proper distofacial embrasure form. he plane of the reduced cusp
should parallel the facial (or lingual) outline of the unreduced
cusp mesiodistally and the cuspal incline emanating from the central
groove faciolingually.

Tooth Preparation for Slot-Retained

• Fig. 10.170 Coves prepared in dentin with No. 1
4 bur, where
Amalgam Retoration appropriate.
When loss of vertical coronal height is approximately 2 to 4 mm,
then use of slots, in horizontal areas where no vertical walls remain,
may be indicated to gain secondary retention form for the complex
amalgam restoration (Figs. 10.169, 10.170, and 10.171). A slot
is a horizontal retention groove in dentin (see Fig. 10.169). Slots
are placed in the gingival loor of a preparation with a No. 330
bur (see Fig. 10.169B, inset). In general, slots should be about
1 mm wide and 1 mm deep, should be placed in the line-angle
areas of the tooth, should be 2 to 4 mm in length (depending on
the distance between remaining vertical walls), and be positioned
0.5 to 1 mm inside the DEJ. In general, one slot per missing axial
line angle should be used. Increasing the width and depth of the
slot does not increase the retentive strength of the amalgam restora-
tion.129 Slot length depends on the extent of the tooth preparation.
A slot may be continuous or segmented, depending on the amount
of missing tooth structure and whether pin retention is being
planned (see subsequent sections). Shorter slots provide as much
resistance to horizontal force as do longer slots.130 Preparations
with shorter slots fail less frequently than do preparations with • Fig. 10.171 Vertical grooves prepared in dentin with a No. 1
4 round
longer slots.130 Slot design should be such that it is independently or No. 169L bur, where appropriate.
retentive as a singular feature (the internal walls of the slot should
be convergent) (see Fig. 10.169B, inset). In addition, the walls of
the slot should work together with other vertical walls to create
392 C HA P T E R 1 0 Clinical Technique for Amalgam Retoration

an overall convergence of the preparation so as to enhance retention is an important adjunct in the restoration of teeth with extensive
of the restoration. caries lesions or fractures.132 Amalgam restorations including pins
In addition to any slot placement, retention grooves and coves have signiicantly greater retention compared with restorations
may be utilized in association with remaining vertical walls (Figs. using boxes only or restorations relying solely on bonding systems.133
10.172 and 10.173). Coves and retention grooves should be prepared However, caution is indicated when using pins. Preparing pinholes
when possible. Coves are prepared in a horizontal plane, and grooves and placing pins may create craze lines or fractures and internal
are prepared in a vertical plane. stresses in dentin.134-136 Such craze lines and internal stress areas
Coves also may be used in preparations using slots (see Fig. may have little or no clinical signiicance, but they may be important
10.169). Proximal retention grooves, as described for wide Class when minimal dentin is present. Preparation steps for pin retention
II preparations, also are placed in the proximal box and in other have increased risk of penetrating into the pulp or perforating the
locations where suicient vertical tooth preparation permits (see external tooth surface. he use of pins decreases the tensile and
Figs. 10.165 and 10.171). horizontal strength of associated amalgam restorations.137,138

Types of Parapulpal Retention Pins

Tooth Preparation for Pin-Retained
he most frequently used type of parapulpal pin is the self-threading
Amalgam Retoration pin. he pin-retained amalgam restoration using self-threading
When severe carious destruction or cusp fracture has resulted in pins originally was described by Going in 1966.139 Friction-locked
the loss of 4 mm or more of vertical coronal height, consideration and cemented pins, although still available, are rarely used (Fig.
should be given to the use of a parapulpal retention pin to regain 10.174). The diameter of the prepared pinhole is 0.0381 to
some of the lost vertical height. A pin-retained amalgam (also 0.1016 mm smaller than the diameter of the pin (Table 10.1).
referred to as a “pin-amalgam”) is deined as any restoration requiring he threads engage dentin as the pin is inserted, thus retaining
the placement of one or more pins in dentin to provide adequate the pin. he elasticity (resiliency) of dentin permits insertion of
resistance and retention forms. Pins are used whenever adequate a threaded pin into a hole of smaller diameter.140 Although the
resistance and retention forms are not able to be established with threads of self-threading pins do not engage dentin for their entire
slots, grooves, or undercuts only.131 Pins placed into prepared width, self-threading pins are the most retentive of the three types
pinholes (also referred to as pin channels) are used to provide of pins (Fig. 10.175), being three to six times more retentive than
auxiliary resistance and retention forms. he pin-retained amalgam cemented pins.141-143

C 3.0 mm
2.0 mm 2.0 mm
C

A B 2.0 mm
3.0 mm 3.0 mm

B
A B C
• Fig. 10.174 Three types of pins. A, Cemented. B, Friction locked.
• Fig. 10.172 Groove (A), slots (B), and coves (C). C, Self-threading.

A B
• Fig. 10.173 Placement of retention grooves. A, Position of No. 169L bur to prepare the retention
groove. B, Groove prepared with No. 14 bur.
 CHAPTER 10 Clinical Technique for Amalgam Retoration 393

Vertical and horizontal stresses, potentially resulting in craze restoration. he shape of the self-threading pin results in the greatest
lines (cracks), are generated in dentin when a self-threading pin retention of amalgam.
is inserted. Craze lines in dentin are related to the size of the pin.
he insertion of 0.787-mm self-threading pins produces more Orientation, Number, and Diameter
dentinal craze lines than does the insertion of 0.533-mm self- Placing pins in a nonparallel manner increases their ability to
threading pins.144 Some evidence suggests, however, that self- retain the restoration; however, bending pins to improve their
threading pins may not cause dentinal crazing.140 Pulpal stress is retention in amalgam is not advised as the bends may interfere
maximal when the self-threading pin is inserted perpendicular to with adequate condensation of amalgam around the pin and decrease
the pulp.145 he depth of the pinhole varies from 1.3 to 2 mm, amalgam retention. In addition, bending also may weaken the pin
depending on the diameter of the pin used.146 Recommended and risk fracture of the adjacent dentin. Pins should be bent only
pinhole depth is generally accepted to be 2 mm. to provide for an adequate amount of amalgam (approximately
Several styles of self-threading pins are available. he hread 1 mm) between the pin and the external surface of the inished
Mate System (TMS) (Coltène/Whaledent Inc., Cuyahoga, Ohio) restoration (on its lateral surface). Only the manufacturer’s speciic
is the most widely used self-threading pin system because of its bending tool should be used to bend a pin, not other hand instru-
(1) versatility, (2) wide range of pin sizes, (3) color-coding system, ments (see subsequent section, Pin Insertion).
and (4) greater retentiveness.147,148 TMS pins are available in gold- In general, increasing the number of pins increases their retention
plated stainless steel or in titanium. Titanium alloy pins (Max in dentin and amalgam. However, the potential beneit of increasing
Restorative Pins, Coltène/Whaledent Inc.) are also available. the number of pins must be compared with the potential problems.
As the number of pins increases, (1) the crazing of dentin and the
Factors Afecting Retention of the Pin in Dentin potential for fracture increase, (2) the amount of available dentin
and Amalgam between the pins decreases, and (3) the strength of the amalgam
Type restoration decreases.149,150 Also, as the diameter of the pin increases,
With regard to the retentiveness of the pin in dentin, the self- retention in dentin and amalgam generally increases. As the number,
threading pin is the most retentive, the friction-locked pin is depth, and diameter of pins increase, the danger of perforating
intermediate, and the cemented pin is the least retentive.141 into the pulp or the external tooth surface increases. Numerous
long pins also may severely compromise the condensation of
Surface Characteritic amalgam and its adaptation to the pins. A pin technique (i.e., a
he number and depth of the elevations (serrations or threads) balance between pin orientation, size, and number) that permits
on the pin inluence the retention of the pin in the amalgam optimal retention with minimal danger to the remaining tooth
structure should be used.151

Extenion Into Dentin and Amalgam

Self-threading pin extension into dentin and amalgam should be
Restorative
approximately 1.5 to 2 mm to preserve the strength of dentin and
material amalgam.141 Extension greater than this is unnecessary for pin
retention and is contraindicated.

Pin Placement Factors and Techniques

Dentin
Pin Size
Four sizes of TMS pins are available (Fig. 10.176), each with a
corresponding color-coded drill (see Table 10.1). Familiarity with
• Fig. 10.175 The complete width of the threads of self-threading pins drill sizes and their corresponding colors is necessary to ensure
does not engage dentin. that a proper-sized pinhole is prepared for the desired pin. It is

TABLE 10.1 The Thread Mate System (TMS) Pins

Illustration (Not to Pin Diameter Drill Diameter Total Pin Length Pin Length Extending
Name Scale) Color Code (inches/mm)* (inches/mm)* (mm) From Dentin (mm)
Regular (standard) Gold 0.031/0.78 0.027/0.68 7.1 5.1
Regular (self-shearing) Gold 0.031/0.78 0.027/0.68 8.2 3.2
Regular (two-in-one) Gold 0.031/0.78 0.027/0.68 9.5 2.8
Minim (standard) Silver 0.024/0.61 0.021/0.53 6.7 4.7
Minim (two-in-one) Silver 0.024/0.61 0.021/0.53 9.5 2.8
Minikin (self-shearing) Red 0.019/0.48 0.017/0.43 7.1 1.5
Minuta (self-shearing) Pink 0.015/0.38 0.0135/0.34 6.2 1

*1 mm = 0.03937 inch.
394 C HA P T E R 1 0 Clinical Technique for Amalgam Retoration

diicult to specify a particular size of pin that is always appropriate Pinhole Location
for a particular tooth. Two determining factors for selecting the Factors that aid in determining the pinhole locations include (1)
appropriate-sized pin are 1) the amount of dentin available to knowledge of normal pulp anatomy and external tooth contours,
safely receive the pin and 2) the amount of retention desired. In (2) a current radiograph of the tooth, (3) a periodontal probe,
the TMS system, the pins of choice for severely involved posterior and (4) the patient’s age. Although the radiograph is only a two-
teeth are the Minikin (0.48 mm) and, occasionally, the Minim dimensional image of the tooth, it may give an indication of the
(0.61 mm). he Minikin pins usually are selected to reduce the position of the pulp chamber and the contour of the mesial and
risk of dentin crazing, pulpal penetration, and root-surface perfora- distal surfaces of the tooth. Consideration also must be given to
tion. he Minim pins usually are used as a backup in case the the placement of pins in areas where the greatest bulk of amalgam
pinhole for the Minikin is overprepared or the pin threads strip will occur so as to compensate (through the reinforcing tendency
dentin during placement resulting in a lack of Minikin pin retention of the amalgam restoration) for the weakening efect of the pins
in the dentin. on the tooth structure.154 Areas of occlusal contacts on the restoration
Larger diameter pins have the greatest retention.152 For example, must be anticipated because a pin oriented vertically and positioned
the Minuta (0.38 mm) pin is approximately half as retentive as directly below an occlusal contact point weakens amalgam signii-
the Minikin and one third as retentive as the Minim pin.147,148 cantly.155 Occlusal clearance should be suicient to provide 2 mm
he Minuta is usually too small to provide adequate retention in of amalgam over the pin.156,157
posterior teeth. he Regular (0.78 mm) or largest diameter pin is Several attempts have been made to identify the ideal location
rarely used because a signiicant amount of crazing in the tooth of the pinhole.135,144,158,159 he following principles of pin placement
(dentin and enamel) may be created during its insertion.144,153 Of are recommended. In the cervical third of molars and premolars
the four types of pins, the Regular pin is associated with the highest (where most pins are located), pinholes should be located near the
incidence of dentinal crack communication with the pulp line angles of the tooth except as described later.151,160 he pinhole
chamber.136 should be positioned no closer than 0.5 to 1 mm to the DEJ or
no closer than 1 to 1.5 mm to the external surface of the tooth,
Number of Pin whichever distance is greater (Fig. 10.177). Before the inal decision
Factors to be considered when deciding how many pins are required is made about the location of the pinhole, the operator should
include (1) the amount of missing tooth structure, (2) the amount probe the gingival crevice carefully to determine if any abnormal
of dentin available to safely receive the pins, (3) the amount of contours exist that would predispose the tooth to an external
retention required, and (4) the size of the pins. As a general rule, perforation. he pinhole should be parallel to the adjacent external
one pin per missing axial line angle should be used. he fewest surface of the tooth.
pins possible should be used to achieve the desired retention for he position of a pinhole must not result in the pin being so
a given restoration. Although the retention of the restoration close to a vertical wall of tooth structure that condensation of
increases as the number of pins increases, an excessive number of amalgam against the pin or wall is jeopardized (Fig. 10.178A). It
pins may fracture the tooth and signiicantly weaken the amalgam may be necessary to irst prepare a recess in the vertical wall with
restoration. the No. 245 bur to permit proper pinhole preparation and to

Color code
for drill

Gold
A

Silver
B

Red
C

Pink
D

• Fig. 10.176 Four sizes of the Thread Mate System (TMS) pins. A, Regular (0.78 mm). B, Minim
(0.61 mm). C, Minikin (0.48 mm). D, Minuta (0.38 mm).
 CHAPTER 10 Clinical Technique for Amalgam Retoration 395

provide a minimum 0.5-mm clearance around the circumference the prominent mesial concavity of the maxillary irst premolar;
of the pin for adequate condensation of amalgam (see Fig. 10.178B (2) at the midlingual and midfacial bifurcations of the mandibular
and C).161 If necessary, after a pin is inappropriately placed, the irst and second molars; and (3) at the midfacial, midmesial, and
operator should provide clearance around the pin to provide middistal furcations of the maxillary irst and second molars. Pulpal
suicient space for the smallest condenser nib to ensure that penetration may result from pin placement at the mesiofacial corner
amalgam is condensed adequately around the pin. A No. 169L of the maxillary first molar and the mandibular first molar.
bur may be used, taking care not to damage or weaken the pin. Mandibular posterior teeth (with their lingual crown tilt), teeth
Pinholes should be prepared on a lat surface that is perpendicular that are rotated in the arch, and teeth that are abnormally tilted
to the proposed direction of the pinhole. his will help prevent in the arch warrant careful attention before and during pinhole
the drill tip from slipping or “crawling” and will allow a depth- placement. When possible, the location of pinholes on the distal
limiting drill (discussed later) to prepare the pinhole as deeply as surface of mandibular molars and lingual surface of maxillary molars
intended (Fig. 10.179). should be avoided. Obtaining the proper direction for preparing
Whenever three or more pinholes are placed, they should be a pinhole in these locations is diicult because of the abrupt laring
located at diferent vertical levels on the tooth, if possible; this of the roots just apical to the CEJ (Fig. 10.180). If the pinhole is
reduces stresses resulting from pin placement in the same horizontal placed parallel to the external surface of the tooth crown in these
plane of the tooth. Spacing between pins, or the interpin distance,
must be considered when two or more pinholes are prepared. he
optimal interpin distance depends on the size of pin to be used.
he minimal interpin distance is 3 mm for the Minikin pin and
5 mm for the Minim pin.160 Maximal interpin distance results
in lower levels of stress in dentin.162
Several posterior teeth have anatomic features that may preclude
safe pinhole placement. Fluted and furcal areas should be avoided.160
External perforation may result from pinhole placement (1) over
2.0 mm

2.0 mm

A
B
1.5 mm 1 mm
• Fig. 10.179 Use of a depth-limiting drill to prepare a pinhole in the
• Fig. 10.177 Pinhole position. A, Position relative to the DEJ. B, Posi-
surface that is not perpendicular to the direction of the pinhole results in
tion relative to external tooth surface.
a pinhole of inadequate depth.

A B C
• Fig. 10.178 A, Pin placed too close to the vertical wall such that adequate condensation of amalgam
is jeopardized. B and C, Recessed area prepared in the vertical wall of the mandibular molar with a
No. 245 bur to provide adequate space for amalgam condensation around the pin.
396 C HA P T E R 1 0 Clinical Technique for Amalgam Retoration

areas, penetration into the pulp is likely.160 For mandibular second Pinhole Preparation
molars that are severely tilted mesially, care must be exercised to he KODEX drill (a twist drill provided in the TMS system)
orient the drill properly to prevent external perforation on the should be used for preparing pinholes (Fig. 10.184). he aluminum
mesial surface and pulpal penetration on the distal surface (Fig. shank of this drill, which acts as a heat absorber, is color coded
10.181). Because of limited interarch space, it is sometimes diicult to allow ready matching with the appropriate pin size (Table 10.2;
to orient the twist drill (see subsequent section, Pinhole Preparation) see also Table 10.1). he drill shanks for the Minuta and Minikin
correctly when placing pinholes at the distofacial or distolingual pins are tapered to provide a built-in “wobble” when placed in a
line angles of the mandibular second and third molars (Fig. 10.182). latch-type contra-angle handpiece. his wobble allows the drill to
When the pinhole locations have been determined, a No. 1 4 be “free loating” and to align itself as the pinhole is prepared.
round bur is irst used to prepare a pilot hole (dimple) approximately his feature minimizes the potential for dentinal crazing or the
one half the diameter of the bur at each location (Fig. 10.183). breakage of small drills.
he purpose of this pilot hole is to permit more accurate placement Because the optimal depth of the pinhole into the dentin is
of the twist drill and to prevent the twist drill from moving laterally 2 mm (only 1.5 mm for the Minikin pin), a depth-limiting drill
(i.e., “crawling”) when it has begun to rotate. should be used to prepare the hole (see Fig. 10.184). his type of
drill is able to prepare the pinhole to the correct depth only when
used on a lat surface that is perpendicular to the drill (see Fig.
10.178C; contrast with Fig. 10.179). When the location for starting
a pinhole is not perpendicular to the desired pinhole direction,
the location area should be lattened or the standard twist drill
should be used (see Fig. 10.184). he standard twist drill has
blades that are 4 to 5 mm in length, which would allow preparation
of a pinhole with an efective depth. Creation of a lat area and
use of the depth-limiting drill provide for a more predictable
outcome and are recommended.
he technique of creating a properly aligned pinhole is as follows:
(1) A pilot hole (dimple) is placed in the horizontal dentin surface
to receive the pin; (2) the correct size twist drill (based on the pin
size) is placed in a latch-type contra-angle handpiece; (3) the twist
A
drill is placed in the gingival crevice beside the location for the
pinhole and positioned such that it lies lat against the external
surface of the tooth; (4) without changing the angulation obtained
from the gingival crevice position, the handpiece is moved occlusally
and the drill placed in the previously prepared pilot hole (Fig.
10.185A); (5) the drill is then viewed from a 90-degree angle to
the previous viewing position to ascertain that the drill also is
angled correctly in this plane (see Fig. 10.185B); (6) with the drill
tip in its proper position and with the handpiece rotating at very
low speed (300–500 rpm), pressure is applied to the drill until
B the depth-limiting portion of the drill is reached (see Fig. 10.185C
• Fig. 10.180 Distal laring of the mandibular molar (A) and palatal root and D); (7) the pinhole is prepared in one or two movements
laring of the maxillary molar (B). Root angulation should be considered without allowing the drill to stop rotating. While still rotating, the
before pinhole placement. drill is immediately removed from the pinhole.

A B
• Fig. 10.181 Care must be exercised when preparing pinholes in mesially tilted molars to prevent
external perforation on mesial surface (A) and pulpal penetration on the distal surface (B).
 CHAPTER 10 Clinical Technique for Amalgam Retoration 397

TABLE 10.2 The Thread Mate System (TMS) Link Series and Link Plus Pins
Illustration (Not to Pin Diameter Drill Diameter Pin Length Extending Pin Length Extending
Name Scale) Color Code (Inches/mm)* (Inches/mm)* from Sleeve (mm) From Dentin (mm)
Link Series
Regular Gold 0.031/0.78 0.027/0.68 5.5 3.2 (single shear)
Regular Gold 0.031/0.78 0.027/0.68 7.8 2.6 (double shear)
Minim Silver 0.024/0.61 0.021/0.53 5.4 3.2 (single shear)
Minim Silver 0.024/0.61 0.021/0.53 7.6 2.6 (double shear)
Minikin Red 0.019/0.48 0.017/0.43 6.9 1.5 (single shear)
Minuta Pink 0.015/0.38 0.0135/0.34 6.3 1 (single shear)
Link Plus
Minim Silver 0.024/0.61 0.021/0.53 10.8 2.7 (double shear)

*1 mm = 0.03937 inch.

• Fig. 10.182 When placing pinholes in molars and interarch space is limited, care must be exercised
to prevent external perforation on distal surface.

Incorrect angulation of the drill may result in pulpal exposure

or external perforation. If the proximity of an adjacent tooth
interferes with placement of the drill into the gingival crevice, a
lat, thin-bladed hand instrument is placed into the crevice and
against the external surface of the tooth to indicate the proper
angulation for the drill.163 Using more than one or two movements,
tilting the handpiece during the drilling procedure, or allowing
the drill to rotate more than briely at the bottom of the pinhole
will result in a pinhole that is too large. he twist drill should
never stop rotating (from insertion to removal from the pinhole)
so as to limit the potential for binding and/or breakage while
creating the pinhole.
Dull twist drills used to prepare pinholes may cause increased
frictional heat and cracks in the dentin. Standlee et al. showed
• Fig. 10.183 Pilot hole (dimple) prepared with a No. 1
4 bur. that a twist drill becomes too dull for use after cutting 20 pinholes
398 C HA P T E R 1 0 Clinical Technique for Amalgam Retoration

B
• Fig. 10.184 A, Two types of KODEX twist drills: standard (a) and depth limiting (b). B, Drills enlarged:
standard (a) and depth limiting (b).

A B C D
• Fig. 10.185 Determining the angulation for the twist drill. A, Drill placed in the gingival crevice, posi-
tioned lat against the tooth, and moved occlusally into position without changing the angulation obtained.
B, A repeated while viewing the drill from position 90 degrees left or right of that viewed in A. C and D,
With twist drill at correct angulation, the pinhole is prepared in one or two thrusts until the depth-limiting
portion of drill is reached and then removed while still rotating.
 CHAPTER 10 Clinical Technique for Amalgam Retoration 399

or less, and the signal for discarding the drill is the need for plastic sleeves (Fig. 10.189). his design has a sharper thread, a
increased pressure on the handpiece.164 Using a drill when its shoulder stop at 2 mm, and a tapered tip to it the bottom of the
self-limiting shank shoulder has become rounded is contraindicated pinhole more readily as prepared by the twist drill. It also provides
(Fig. 10.186). A worn and rounded shoulder may not properly a 2.7-mm length of pin to extend out of dentin, which usually
limit pinhole depth and may permit pins to be placed too deeply. needs to be shortened with the use of a handpiece bur. heoretically,
and as suggested by Standlee et al., these innovations should reduce
Pin Deign the stress created in the surrounding dentin as the pin is inserted
Several designs are available for each of the four sizes of TMS and reduce the apical stress at the bottom of the pinhole.164 Kelsey
self-threading pins: standard, self-shearing, two-in-one, Link Series, et al. reported that the two-in-one Link Plus irst and second pins
and Link Plus (Fig. 10.187). he Link Series pin is free loating seat completely into the pinhole before shearing.165
in a plastic sleeve, which allows self-alignment as it is threaded he self-shearing pin has a total length that varies according
into the pinhole (Fig. 10.188). When the pin reaches the bottom to the diameter of the pin (see Table 10.1). It also consists of a
of the hole, the pin shears of at a machined narrow area, leaving lattened head to engage the hand wrench or the appropriate
a length of pin extending from dentin. he plastic sleeve is then handpiece chuck for threading into the pinhole. When the pin
discarded. he Minuta, Minikin, Minim, and Regular pins are approaches the bottom of the pinhole and begins to bind, the
available in the Link Series. Link Series pins are recommended head of the pin shears of leaving a length of pin extending from
because of their versatility, self-aligning ability, and dentin.
retentiveness.147
Link Plus self-threading pins are also self-shearing and are
available as single and two-in-one pins contained in color-coded

• Fig. 10.188 Cross-sectional view of Link Series pin.

2.7 mm 2 mm

• Fig. 10.186 Minikin self-limiting drill with worn shank shoulder (left) Plastic sleeve Pin No. 2 Pin No. 1
compared with a new drill with an unworn shoulder (right). • Fig. 10.189 Link Plus pin.

• Fig. 10.187 Five designs of the Thread Mate System (TMS) pins. A, Standard. B, Self-shearing.
C, Two-in-one. D, Link Series. E, Link Plus.
400 C HA P T E R 1 0 Clinical Technique for Amalgam Retoration

he two-in-one pin is actually two pins in one, with each one rotated one quarter to one half turn counterclockwise to reduce
being shorter than the standard pin. The two-in-one pin is the dentinal stress created by the end of the pin that is pressing
approximately 9.5 mm in length and has a lattened head to aid on dentin at the bottom of the pinhole.170 he hand wrench should
in its insertion. When the pin reaches the bottom of the pinhole, be removed from the pin carefully. If the hand wrench is used
it shears approximately in half, leaving a length of pin extending without rubber dam isolation, a gauze throat shield must be in
from dentin with the other half remaining in the hand wrench or place, and a strand of dental loss, approximately 30 to 38 cm in
the handpiece chuck. his second pin may be positioned in another length, should be tied securely to the end of the wrench (Fig.
pinhole and threaded to place in the same manner as the standard 10.193) to prevent accidental swallowing or aspiration by the
pin. he designs available with each size of pin are shown in Tables patient.
10.1 and 10.2. he lengths of the pins are evaluated after placement (see Fig.
Selection of a particular pin design is inluenced by the size of 10.191C). Any length of pin greater than 2 mm should be removed.
the pin being used, the amount of interarch space available, and A sharp No. 1 4 , No. 1 2 , or No. 169L or 245 bur, at high speed
operator preference. With minimal interarch space, the two-in-one and oriented perpendicular to the pin, may be used to remove the
design may be undesirable because of its length. It has been reported excess length (Fig. 10.194A). If oriented otherwise, the rotation
that 93% of Link Series and Link Plus two-in-one pins extended
to the optimal depth of 2 mm.166-169 Even so, both the two-in-one
pin and the self-shearing pin may occasionally fail to reach the
bottom of the pinhole.

Pin Inertion
he TMS utilizes hand wrenches to place the self-threading pins
(Figs. 10.190A–C and 10.191A). Link Series and Link Plus pins
are contained in color-coded plastic sleeves that it a latch-type
contra-angle handpiece or a specially designed plastic hand wrench A
(see Fig. 10.190D). In addition, handpiece chucks are available
(Fig. 10.192). he results of studies are conlicting as to which
method of pin insertion produces the best results. he latch-type
handpiece is recommended for the insertion of the Link Series B
and the Link Plus pins. he hand wrench is recommended for the
insertion of standard pins.
When using the latch-type handpiece, a Link Series or a Link
Plus pin is inserted into the handpiece and positioned over the
pinhole. he handpiece is activated at low speed until the plastic C
sleeve shears from the pin. he pin sleeve is then discarded. For
low-speed handpieces with a low gear, the low gear should be used.
Using the low gear increases the torque and increases the tactile
sense of the operator. It also reduces the risk of stripping the
threads in dentin during pin insertion. D
A standard pin is placed in the appropriate hand wrench (see
Fig. 10.191A) and slowly threaded clockwise into the pinhole until
a deinite resistance (indicating the pin has reached the bottom of • Fig. 10.190 Hand wrenches for the Thread Mate System (TMS) pins.
the pin hole) is felt (see Fig. 10.191B). he pin should then be A, Regular and Minikin. B, Minim. C, Minuta. D, Link Series and Link Plus.

A
B C
• Fig. 10.191 A, Use of a hand wrench to place a pin. B, Threading the pin to the bottom of the pinhole
and reversing the wrench one quarter to one half turn. C, Evaluating the length of the pin extending from
dentin.
 CHAPTER 10 Clinical Technique for Amalgam Retoration 401

of the bur may loosen the pin by rotating it counterclockwise and contour of the inal restoration such that there will be adequate
unthreading it out of the pinhole. During removal of excess pin bulk of amalgam between the pin and the external surface of the
length, the assistant may apply a steady stream of air to the pin inal restoration (see Fig. 10.194B and C). When pins require
and have the high-volume evacuator tip positioned to remove the bending, the TMS bending tool (Fig. 10.195A) must be used. he
pin segment. Also, during removal of excess pin length, the pin bending tool should be placed on the pin where the pin is to be
may be stabilized with a small hemostat or cotton pliers. After bent, and with irm controlled pressure, the bending tool should
placement, the pin should be tight, immobile, and not easily be rotated until the desired amount of bend is achieved (see Fig.
withdrawn. Every pin must be assessed with cotton pliers for stability 10.195B–D). Use of the bending tool allows placement of the
immediately after placement. fulcrum at some point along the length of the exposed pin. Other
he preparation is viewed from all directions with a mirror instruments should not be used to bend a pin because the location
(particularly from the occlusal direction) to determine if any pins of the fulcrum would be at the oriice of the pinhole (i.e., the
need to be bent so as to be positioned within the anticipated surface of the dentin). Force placed at this area may cause crazing
or fracture of dentin, and the abrupt or sharp bend that usually
results increases the chances of breaking the pin (Fig. 10.196).
Also the operator has less control when pressure is applied with a
hand instrument, and the risk of slipping is increased. Pins should
only be bent if absolutely necessary, never simply to make them
parallel or based on a notion that bending them will increase their
A relative retentiveness.

Possible Problems With Pins

Failure of Pin-Retained Retoration
B he failure of pin-retained restorations might occur at any of ive
diferent locations (Fig. 10.197). Failure may occur (1) within the
restoration (restoration fracture), (2) at the interface between the
pin and the restorative material (pin–restoration separation), (3)
• Fig. 10.192 Handpiece chucks for the Thread Mate System (TMS)
within the pin (pin fracture), (4) at the interface between the pin
regular self-shearing and Minikin pins (A) and TMS Minuta pins (B).

A B
• Fig. 10.193 Precautions to be taken if a rubber dam is not used. A, Gauze throat shield. B, Hand
wrench with 30 to 38 cm of dental tape attached.

A B C
• Fig. 10.194 A, Use of sharp No. 1
4 bur held perpendicular to the pin to shorten the pin. B and
C, Evaluating the preparation to determine the need for bending the pins.
402 C HA P T E R 1 0 Clinical Technique for Amalgam Retoration

A
B

C D
• Fig. 10.195 A, The Thread Mate System (TMS) bending tool. B, Use of the bending tool to bend the
pin. C and D, The pin is bent to a position that provides adequate bulk of amalgam between the pin and
the external surface of the inal restoration.

Chipped Sharp bend

dentin

Incorrect
Incorrect
A B C
• Fig. 10.196 A, A Black spoon excavator or other hand instrument should not be used to bend the
pin. B and C, Use of hand instruments may create a sharp bend in the pin and fracture dentin.
 CHAPTER 10 Clinical Technique for Amalgam Retoration 403

Restorative material Restorative material

Penetration Into the Pulp and Perforation of the External
Tooth Surface
a
Penetration into the pulp or perforation of the external surface of
the tooth is obvious if hemorrhage occurs in the pinhole after
removal of the drill. Usually the operator is able to perceive when
b pulp penetration or root perforation has occurred by an abrupt
loss of resistance of the drill to hand pressure. Also if a standard
or Link Series pin continues to thread into the tooth beyond the
2-mm depth of the pinhole, this is an indication of a penetration
c or perforation. A pulpal penetration might be suspected if the
patient is anesthetized and has sudden sensitivity when the pinhole
is being completed or the pin is being placed. However, if the
d
patient still has profound pulpal anesthesia, pulpal penetration of
the pinhole or pin may not be perceived.
Pulpal penetration is treated as any other small mechanical
e exposure if the tooth has been asymptomatic. When preparation
of the pinhole causes a pulp exposure, any hemorrhage is controlled.
A calcium hydroxide liner is placed over the opening of the pinhole,
Dentin Dentin and another hole is prepared 1.5 mm away. If the exposure is
• Fig. 10.197 Five possible locations of failure of pin-retained restora- discovered as the pin is being placed, the pin is removed and the
tions: fracture of restorative material (a), separation of pin from restorative area of pulp penetration treated as described. Although certain
material (b), fracture of pin (c), separation of pin from dentin (d), fracture studies have shown that the pulp tolerates pin penetration when
of dentin (e). the pin is placed in a relatively sterile environment, it is not recom-
mended that pins be left in place when a pulpal penetration has
occurred.157,171 If the pin were left in the pulp, (1) the depth of
the pin into pulpal tissue would be diicult to determine, (2)
and dentin, and (5) within dentin (dentin fracture). Failure is considerable postoperative sensitivity might ensue, and (3) the pin
more likely to occur at the pin–dentin interface than at the location might complicate subsequent endodontic therapy. Regard-
pin–restoration interface. he operator must keep these areas of less of the method of treatment rendered, the patient must be
potential failure in mind at all times and apply necessary principles informed of the pulpal penetration or root perforation at the
to reduce failure risk. completion of the appointment. he afected tooth should be
evaluated periodically using appropriate diagnostic tests including
Broken Drill and Broken Pin radiographs. he patient should be instructed to inform the dentist
Occasionally, a twist drill breaks if it is stressed laterally or allowed if any discomfort develops.
to stop rotating before it is removed from the pinhole. Use of a Because most teeth receiving pins have had extensive caries,
sharp twist drill helps to limit the possibility of drill breakage. restorations, or both, the health of the pulp is likely compromised.
Pins also may break during bending if care is not exercised. he he ideal treatment of a pulpal penetration for such a compromised
treatment for broken drills and broken pins is to choose an alterna- tooth generally is endodontic therapy. Furthermore, endodontic
tive location, at least 1.5 mm remote from the broken item, and treatment should be strongly considered when such a tooth is to
prepare another pinhole and place another pin. Removal of a receive an indirect restoration.
broken pin or drill is diicult, if not impossible, and usually should An external perforation might be suspected if an unanesthetized
not be attempted. patient senses pain when a pinhole is being prepared or a pin is
being placed in a tooth that has had endodontic therapy. Observation
Looe Pin of the angulation of the twist drill or the pin may help in the
Self-threading pins sometimes do not engage dentin properly because determination of whether a pulpal penetration or external perfora-
the pinhole was inadvertently prepared too large or a self-shearing tion has occurred. Perforation of the external surface of the tooth
pin failed to shear, resulting in stripped-out dentin. he pin should may occur occlusal or apical to the gingival attachment. Careful
be removed from the tooth and the pinhole re-prepared with the probing and radiographic examination must be used to accurately
next largest size drill, and the appropriate pin should be inserted. diagnose the location of a perforation. he method of treatment
Preparing another pinhole of the same size as the original, 1.5 mm for a perforation often depends on the experience of the operator
from the original pinhole, also is acceptable. and the particular circumstances of the tooth being treated.
As described earlier, a properly placed pin may be loosened hree options are available for perforations that occur occlusal
while being shortened with a bur, if the bur is not held perpen- to the gingival attachment: (1) he pin may be cut of lush with
dicularly to the pin and the pin stabilized. A loose pin may be the tooth surface and no further treatment rendered; (2) the pin
removed from the pinhole by holding a rotating bur parallel to may be cut of lush with the tooth surface and the preparation
the pin and lightly contacting the surface of the pin; this causes for an indirect restoration extended gingivally beyond the perfora-
the pin to rotate counterclockwise out of the pinhole. A second tion; or (3) the pin may be removed, if still present, and the
attempt should be made with the same-size pin. If the second external aspect of the pinhole enlarged slightly and restored with
pin fails to irmly engage the dentin, a larger hole is prepared, amalgam. Surgical relection of gingival tissue may be necessary
and the appropriate pin is inserted. Preparing another pinhole of to render adequate treatment. he location of perforations occlusal
the same size 1.5 mm from the original pinhole also is to the attachment often determines the option to
acceptable. be pursued.
404 C HA P T E R 1 0 Clinical Technique for Amalgam Retoration

A B

C D
• Fig. 10.198 External perforation of a pin. A, Radiograph showing the external perforation of a pin.
B, Surgical access to extruding pin (arrow). C, Pin cut lush with the tooth structure and crown-lengthening
procedure performed. D, Length of pin removed.

Two options are available for perforations that occur apical to forms for the inal indirect restoration (e.g., crown or bridge
the gingival attachment: (1) Relect the tissue surgically, perform retainer). he retention of the foundation material should not be
any necessary ostectomy, enlarge the pinhole slightly, and restore compromised by tooth reduction during the inal preparation for
with amalgam; or (2) perform a crown-lengthening procedure and the indirect restoration. he foundation also should provide the
place the margin of a cast restoration gingival to the perforation resistance form against forces that otherwise might fracture the
(Fig. 10.198). As with perforations located occlusal to the gingival remaining tooth structure.
attachment, the location of the perforation and the design of the In contrast to a conventional complex amalgam restoration, an
present or planned restoration help determine which option to amalgam foundation may not depend primarily on the remaining
pursue. As with pulpal penetration, the patient must be informed coronal tooth structure for support. Instead it may rely mainly on
of the perforation and the proposed treatment. he prognosis of secondary preparation retention features (proximal retention grooves,
external perforations is favorable when they are recognized early coves, slots, pins). A temporary or caries-control restoration may
and treated properly. serve as a foundation, but only if the retention and resistance
forms of the restoration are appropriate.
Considerations for the Use of Slots or Pins A temporary or caries-control restoration is used to restore a
Slot retention may be used in conjunction with pin retention or tooth when deinitive treatment is uncertain or when several teeth
as an alternative to it.172 Some operators use slot retention and require immediate attention for control of caries lesions. It also
pin retention interchangeably. Others more frequently use slot may be used when a tooth’s prognosis is questionable. A temporary
retention in preparations with vertical walls that allow retention or control restoration might depend only on the remaining coronal
grooves to oppose one another. Pin retention is used more frequently tooth structure for support, however, using few auxiliary retention
in preparations with few or no vertical walls. Slots are particularly features. When preparing a tooth for either a foundation or a
indicated in short clinical crowns and when cusp reduction has temporary restoration, remaining unsupported enamel may be left
been limited to 2 or 3 mm.172 More tooth structure is removed (except at the gingival aspect) to aid in forming a matrix for amalgam
in slot preparation as compared with pin placement; however, slots condensation. In this case the remaining unsupported enamel will
are less likely to (1) create microfractures in dentin, (2) perforate subsequently be removed when the preparation for the indirect
the tooth surface, or (3) penetrate into the pulp. Slot placement restoration is accomplished. Occasionally, when providing a
does not elicit an inlammatory response, whereas medium-sized temporary or control restoration, suicient retention and resistance
self-threading pins may elicit an inlammatory response if placed forms are included in the preparation to meet the requirements
within 0.5 mm of the pulp.158 he retention potential of slots and of a foundation.
pins is similar.173-176 As a rule, foundations are placed in anticipation of full-coverage
indirect restorations. Not all teeth with foundations, however,
need to be immediately restored with full-coverage crowns. For
Tooth Preparation for Amalgam Foundation example, amalgam may be used as a deinitive partial-coverage
An amalgam foundation may be used as part of the initial restoration restoration of endodontically treated teeth if only minimal coronal
of a severely involved tooth. he tooth is restored so that the damage has occurred.177 he greatest inluence on fracture resistance
restorative material (amalgam, composite, or other) serves to replace is the amount of remaining tooth structure; therefore restorations
lost tooth structure necessary to provide retention and resistance that conserve natural tooth structure are preferred.178
 CHAPTER 10 Clinical Technique for Amalgam Retoration 405

more than half the diameter of the pin, any retentive efect of the
pin probably has been eliminated.
he location of the pinhole from the external surface of the
tooth for foundations depends on (1) the occlusogingival location
of the pin (external morphology of the tooth), (2) the type of
restoration to be placed (e.g., a porcelain-fused-to-metal [PFM]
requires more reduction than a full gold crown), and (3) the type
of margin to be prepared. Preparations with heavily chamfered
margins at a normal occlusogingival location require slot and pin
placement at a greater axial depth. he length of the pins also
must be adjusted to permit adequate occlusal reduction without
exposing the pins. Proximal retention grooves still should be used,
wherever possible.
Completion of all inal preparation steps is accomplished as
described previously. An RMGI liner/base may be applied as
indicated. A liner or base should not extend closer than 1 mm to
a slot or a pin.
• Fig. 10.199 Pulp chamber retention with 2- to 4-mm extension of the
foundation into the canal spaces.
Pulp Chamber Retention of Foundations
he pulp chamber may be efectively used to retain an amalgam
foundation in multirooted, endodontically treated teeth. his
Amalgam and composite resin are the direct restorative materials alternative to the use of slots/pins is recommended when (1) dimension
used for foundations. RMGIs may be used to block out minor of the pulp chamber is adequate to provide retention and bulk of
undercut areas of the preparation for an indirect restoration that amalgam, and (2) dentin thickness in the region of the pulp chamber
do not draw. Amalgam may be preferred by some clinicians because is adequate to provide rigidity and strength to the tooth.180 Additional
it is easy to use and it is strong. While slots and threaded pins extension of 2 to 4 mm into the root canal space is recommended
may be used for secondary retention in vital teeth, prefabricated when the pulp chamber height is 2 mm or less (see Fig. 10.199).181
posts and cast post/cores are used to provide additional retention When the pulp chamber height is 4 to 6 mm in depth, no advantage
for the foundation material in endodontically treated teeth receiving is gained from additional extension into the root canal space. After
foundations. Prefabricated posts and cast post/cores are generally matrix application, amalgam is thoroughly condensed into the pulp
used on anterior teeth or single-canal premolars that have little or chamber (and radicular space if indicated) and the coronal portion
no remaining coronal tooth structure. Note, however, that there of the tooth. Natural undercuts in the pulp chamber and the divergent
must be adequate remaining natural tooth structure to allow creation root canals provide the necessary retention form. he resistance
of a ferrule so as to achieve long-term clinical success. he pulp form against forces that otherwise may cause tooth fracture is improved
chamber and entrance to the root canals of endodontically treated by gingival extension of the crown preparation approximately 2 mm
molar teeth typically provide retention for foundations, and it is beyond the foundation onto sound tooth structure to establish the
not necessary to use any form of intraradicular retention (i.e., post necessary ferrule once the indirect restoration is in place. his
material extended further into the root canal space) extension should have a total taper of opposing walls of less than
(Fig. 10.199). 10 degrees.182 If the pulp chamber height is less than 2 mm, the
use of a prefabricated post, cast post and core, pins, or slots should
Slot and/or Pin Retention of Foundations be considered for additional retention of the foundation
he technique of tooth preparation for a foundation depends on material.
the type of retention that is selected—slot retention, pin retention, he preparation should then be cleaned, carefully inspected as
or both. he techniques have in common the axial location of the indicated in General Concepts Guiding Preparation for Amalgam
retention. Slots and pins for the retention of amalgam foundations Restorations, and any inal modiications completed.
are placed slightly more axial (farther inside the DEJ) than indicated
for deinitive complex amalgam restorations. he actual pulpal
positioning depends on the type of indirect restoration that has Retorative Technique for Complex
been planned. he preparation for an indirect restoration should Amalgam Preparation
not eliminate or cut into the foundation’s retentive features.
Severely broken teeth with few or no vertical walls, in which Desensitizer Placement
an indirect restoration is indicated, may require a pin-retained A dentin desensitizer is placed over the prepared tooth structure
foundation. he main diference between the use of pins for per manufacturer instructions. Excess moisture is removed without
foundations and the use of pins in deinitive complex restorations desiccating the dentin.
is the distance of the pinholes from the external surface of the
tooth.179 For foundations, the pinholes must be located farther Matrix Placement
from the external surface of the tooth (farther internally from the One of the most diicult steps in restoring a severely compromised
DEJ), and more bending of the pins may be necessary to allow posterior tooth is development of a satisfactory matrix to assist in
for adequate axial reduction of the foundation without exposing formation of the anatomic shape of the restoration. Fulilling the
the pins during the cast-metal tooth preparation. Any removal of objectives of a matrix is complicated by possible gingival extensions,
the restorative material from the circumference of the pin would missing line angles, and restoration of reduced cusps typical of
compromise its retentive efect. If the material is removed from complex tooth preparations.
406 C HA P T E R 1 0 Clinical Technique for Amalgam Retoration

Univeral Matrix he Tolemire retainer is loosened one half turn, and the strip
he Tolemire retainer and band may be used successfully for of matrix material is inserted next to the opening between the
most amalgam restorations (Fig. 10.200). Use of the Tolemire matrix band and the tooth. he retainer is then tightened and
retainer requires suicient tooth structure to retain the band the matrix is completed. Sometimes it is helpful to place a small
after it is applied. Even when the Tolemire retainer is placed amount of rigid material (hard-setting polyvinyl siloxane [PVS] or
appropriately an opening may remain next to an area of the compound or light-cured lowable resin) between the strip and the
preparation tooth structure. In this case a closed system may be open aspect of the band retainer to stabilize and support the strip (see
developed as illustrated in Fig. 10.201. A strip of matrix mate- Fig. 10.201G and H).
rial that is long enough to extend from the mesial to the distal When little tooth structure remains and deep gingival
corners of the tooth is prepared. he strip must extend into these margins are present, the Tofflemire matrix may not func-
corners suiciently that the band, when tight, holds the strip in tion successfully, and the AutoMatrix system (DENTSPLY
position. Also it must not extend into the proximal areas, or a Caulk, Milford, DE) may be an alternative method
ledge would result in the restoration contour (see Fig. 10.201F). (Fig. 10.202).

A B C

D E F

G H I

J K L
• Fig. 10.200 A, Mandibular irst molar with fractured distolingual cusp. B, Insertion of wedges. C, Initial
tooth preparation. D and E, Removal of any soft dentin and/or any remaining old restorative material as
indicated. F, Application of a liner and a base (if necessary). G, Preparation of pilot holes. H, Alignment
of the twist drill with the external surface of the tooth. I, Preparation of pinholes. J, Insertion of Link pins
with a slow-speed handpiece. K, Depth-limiting shoulder (arrowhead) of inserted Link Plus pin. L, Use of
a No. 14 bur to shorten pins.
 CHAPTER 10 Clinical Technique for Amalgam Retoration 407

M N O

P Q R

S T
• Fig. 10.200, cont’d M, Bending pins (if necessary) with a bending tool. N, Final tooth preparation.
O, Toflemire retainer and matrix band applied to the prepared tooth. P, Relecting light to evaluate the
proximal area of the matrix band. Q, Preparation overilled. R, Restoration carved. S, Relecting light to
evaluate the adequacy of the proximal contact and contour. T, Restoration polished.

AutoMatrix or eventually fail because of lack of suicient strength secondary

he AutoMatrix is a retainerless matrix system designed for any to internal voids or fractures. Matrix stability during condensation
tooth regardless of its circumference and height. AutoMatrix is especially important for slot-retained amalgam restorations. If
bands are supplied in three widths: (1) 4.76 mm, (2) 6.35 mm, the matrix is not secure during condensation, it may slip out of
and (3) 7.94 mm. he medium band is available in two thicknesses position causing separation of the main bulk of the amalgam from
(0.038 mm and 0.05 mm). he 4.76, 6.35, and 7.94 mm band its retentive slots or pins.
widths are available in the 0.05 mm thickness only. Advantages
of this system include (1) convenience, (2) improved visibility Insertion, Contouring, and Finishing of Amalgam
because of absence of a retainer, and (3) ability to place the autolock A high-copper alloy is strongly recommended for the complex
loop on the facial or lingual surface of the tooth. Disadvantages amalgam restoration because of excellent clinical performance and
of this system are that (1) the band is lat and diicult to burnish high early compressive strengths.183-185 Spherical alloys have a higher
and is sometimes unstable even when wedges are in place, and early strength than admixed alloys, and spherical alloys may be
(2) development of proper proximal contours and contacts may condensed more quickly and with less pressure so as to ensure
be diicult. Use of the AutoMatrix system is illustrated in Fig. good adaptation in slots and around the pins. However, proximal
10.203. contacts may be easier to achieve with admixed alloys because of
Regardless of the type of matrix system used, the matrix must their condensability. Alloys that provide extended working time
be stable during condensation of the amalgam. he matrix should are necessary to allow adequate time for condensation, removal of
extend beyond the gingival margins of the preparation enough to the matrix band, and inal carving. Because complex amalgam
provide support for the matrix and to permit appropriate wedge restorations usually are quite large, a slow-set or medium-set
stabilization. he matrix should extend occlusally beyond the amalgam may be selected to provide more time for the carving
marginal ridge of the adjacent tooth by 1 to 2 mm. If the matrix and adjustment of the restoration.
for a complex amalgam restoration is not stable during condensation, Regardless of the type of alloy chosen, care must be taken to con-
a homogeneous restoration will not be developed. An improperly dense the amalgam thoroughly in and around the retentive features of
condensed amalgam may disintegrate when the matrix is removed, the preparation. If a mix of amalgam becomes dry or crumbly, a new
408 C HA P T E R 1 0 Clinical Technique for Amalgam Retoration

A B C

D E F

G H I
• Fig. 10.201 Technique for closing the open space of the Toflemire matrix system. A, Tooth prepara-
tion with wedges in place. B, Open aspect of the matrix band next to the prepared tooth structure. C
and D, Cutting an appropriate length of the matrix material. E, Insertion of a strip of the matrix material.
F, Closed matrix system. G and H, Placement of the rigid supporting material between the strip and the
matrix band, and contouring, if necessary. I, Restoration carved.

mix is triturated immediately. Placement of a whole freshly mixed is removed with an explorer or a Black spoon. Tolemire matrices
mass of amalgam (instead of using the amalgam carrier to place incre- are removed irst by loosening and removing the retainer while
ments of amalgam) increases the rate of completely illing the defect. the wedges are still in place. Leaving the wedges in place may help
Special care must be taken when this technique is used to ensure prevent fracturing the freshly condensed amalgam. It may be
the amalgam is well adapted in and around all retentive areas and at beneicial to place a ingertip on the occlusal surface of the restored
all margins. tooth to stabilize the matrix while loosening and removing the
With a complex (or any large) amalgam, carving time must be retainer from the band. his is to reduce the risk of fracturing the
properly allocated. he time spent on carving occlusal anatomy freshly inserted amalgam while applying the force necessary to
(while the matrix is still in place) must be shortened to allow loosen the retainer. he matrix is removed by sliding each end of
adequate time for carving the more inaccessible gingival margins the band in an oblique direction (i.e., moving the band facially
and the proximal and axial contours (after the matrix is removed). or lingually while simultaneously moving it in an occlusal direction).
he bulk of excess amalgam on the occlusal surface is removed Moving the band obliquely toward the occlusal surface minimizes
and the initial anatomic contours are rapidly developed, especially the possibility of fracturing the marginal ridge. Preferably the matrix
the marginal ridge heights and cuspal inclines, with a discoid band should be removed in the same direction as the wedge place-
carver and/or Hollenback carver. he occlusal embrasures are deined ment to prevent dislodging the wedges. AutoMatrix bands are
by running the tine of an explorer against the internal aspect of removed by using the system’s instruments and, after the band is
the matrix band. Appropriate marginal ridge heights and embrasures open, by the same technique described for Tolemire-retained
reduce the potential of fracturing the marginal ridge when the matrices. Carving of the restoration is then continued (see Figs.
matrix is removed. 10.200R and 10.203N).
Matrix removal is crucial when completing complex amalgam Wedges are then removed, and the gingival excess on the proximal
restorations, especially slot-retained restorations.172 If the matrix surface is removed with an amalgam knife or explorer. Facial and
is removed prematurely, the newly placed restoration may fracture lingual contours are developed with a Hollenback carver, amalgam
immediately adjacent to the areas where amalgam has been con- knife, or explorer to complete the carving (see Figs. 10.200R and
densed into the slot(s). Any rigid material supporting the matrix S and 10.201I). Appropriately shaped rotary instruments are used
 CHAPTER 10 Clinical Technique for Amalgam Retoration 409

Autolock loop

Lock-release hole
Coil

C D
• Fig. 10.202 A, AutoMatrix retainerless matrix system. B, AutoMatrix band. C, Automate II tightening
device. D, Shielded snippers. (A, Courtesy Dentsply Caulk, Milford, DE.)

to complete the occlusal contouring if amalgam has become so he rubber dam is removed and the occlusal surface of the
hard that the force needed to carve with hand instruments might amalgam is adjusted to obtain appropriate occlusal contacts. hin,
fracture portions of the restoration. unwaxed dental loss may be carefully passed through the proximal
Each proximal contact is evaluated by using a mirror occlusally contacts one time to remove amalgam shavings and to smooth the
and lingually to ensure that no light can be relected between the proximal surface of amalgam. Amalgam excess and loose particles
restoration and the adjacent tooth at the level of the proximal are removed from the gingival sulcus by moving the loss occlu-
contact (see Fig. 10.200S). When the proper proximal contour or sogingivally and faciolingually. he patient should be cautioned
contact is not achieved in a large, complex restoration, it may be not to chew with the restoration for 24 hours. Fast-setting high-
possible to prepare a conservative “ideal” two-surface tooth prepara- copper amalgam may be prepared for an indirect restoration within
tion within the initial amalgam to restore the proper proximal 30 to 45 minutes after insertion of the foundation. Further inishing
surface contours. Amalgam forming the walls of this “ideal” and polishing of the complex amalgam may be accomplished, if
preparation must have suicient bulk to prevent future fracture. desired, as early as 24 hours after placement (see Fig. 10.200T).
410 C HA P T E R 1 0 Clinical Technique for Amalgam Retoration

A B C

D E F

G H I

J K L

M N O
• Fig. 10.203 Application of AutoMatrix for developing a pin-retained amalgam crown on the mandibular
irst molar. A, Tooth preparation with wedges in place. B, Enlargement of the circumference of the band,
if necessary. C, Burnishing the band with an egg-shaped burnisher. D–F, Placement of the band around
the tooth, tightening with an Automate II tightening device, and setting wedges irmly in place. G, Applica-
tion of the green compound. H, Contouring of the band with the back of a warm Black spoon excavator
so the softened compound will allow matrix deformation. I, Overilling the preparation and carving the
occlusal aspect. J and K, Use of shielded snippers to cut an autolock loop. L, Separating the band with
an explorer. M, Removing the band in an oblique direction (facially with some occlusal vector). N, Restora-
tion carved. O, Restoration polished.
 CHAPTER 10 Clinical Technique for Amalgam Retoration 411

Summary
Dental amalgam remains a predictable, cost-efective, and safe use retention grooves/coves in remaining vertical walls as well as
means for the restoration of posterior (and some anterior) teeth slots, pins, and customized matrix designs to efect successful restora-
that are missing various amounts of tooth structure. he design tions. Restoration of normal anatomic contours and therefore
of a successful tooth preparation must be based on the material normal clinical function may be readily accomplished with dental
properties of dental amalgam and the successful use of primary amalgam.
and secondary means of restoration retention. Complex preparations

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