40 Chapter 2: Operative Dentistry and Prosthodontics

ANSWE RS

1. The correct answer is C. The patient has amel- wide at the enamel surface and converges with
ogenesis imperfecta, a rare hereditary condition the apex toward the DEJ. Then in dentin, caries
that results in a reduced amount of enamel, progresses faster because of less mineral content.
which is softer than normal enamel and is yellow V-shaped caries has a broad base at the DEJ and
in color and pitted. Both primary and perma- converges to the apex toward the pulp.
nent teeth are affected. The dentin and pulps
are normal, and there is no increase in rate of 5. The correct answer is D. Turbid dentin is the
caries. The only necessary treatment is cosmetic only zone listed, which is infected dentin. Bac-
treatment, which is best accomplished by full terial invasion has occurred in dentinal tubules
Operative Dentistry and

coverage crowns. Answer choice D refers the pa- of turbid dentin. Normal, subtransparent, and
tient to an eating disorders clinic. This would be transparent dentin are all affected dentin and
Prosthodontics

inappropriate in this case, but if the patient ex- are capable of remineralization. The dentin in
hibits enamel erosion on the lingual surfaces of an arrested or remineralized lesion is eburnated
the teeth, referral to a therapist who specializes or sclerotic dentin.
in treatment of eating disorders may be appro-
priate. 6. The correct answer is A. Swallowing, masti-
cation, and speech are considered functional
2. The correct answer is D. The patient has a con- movements of the mandible. Parafunctional
genitally missing permanent right mandibular movements are sustained activities that occur be-
second premolar and an over-retained primary yond the normal functions of those mentioned
second molar in that space. Primary teeth are above. Bruxism is initiated at a subconscious
likely to exhibit furcation canals, and if infec- level diurnal, nocturnal, or both. It is the sus-
tion is present radiographically in the furcation, tained grinding, rubbing together, or gnashing
the most appropriate treatment is to extract the of the teeth with greater than normal chewing
tooth. Ideal replacement of the missing tooth in force. Nail biting is an example of parafunctional
a healthy patient would be to place a single-unit activity. Parafunctional activity can cause exces-
implant. However, this patient is HIV positive sive wear, widening of the PDL, and mobility,
and smokes two packs per day. Both are likely to migration, or fracture of the teeth. Clenching is
impede healing, so placement of an implant is the pressure and clamping of the jaws and teeth
not the most desirable treatment option. A three- together, frequently associated with acute ner-
unit fixed partial denture would be the most ap- vous tension or physical effort.
propriate treatment.
7. The correct answer is C. It is recommended
3. The correct answer is B. Incipient caries and to restore the patient to a functional status by
enamel hypocalcification appear similar clini- eliminating caries and controlling periodontal
cally. To properly diagnose, wet the surface of the disease prior to treatment planning with fixed
tooth. If the lesion fully or partially disappears, prosthodontics. Veneers, crowns, fixed partial
and drying it again causes it to reappear, the di- dentures, and partial coverage restorations are
agnosis is smooth surface incipient caries. Nei- contraindicated with both active caries and ac-
ther radiograph nor transillumination will show tive periodontal disease. Extraction is a final
facial incipient lesions. Caries detector will ap- treatment option but may not be required at
pear similar with both lesions. Both lesions will this point. Caries control and treatment plan-
appear hard and smooth, so a sharp explorer will ning prior to restoration of edentulous space(s)
not diagnose. is recommended. Endodontically treated tooth
often require cast post and core fabrication prior
4. The correct answer is A. In interproximal or to fixed restorations.
smooth surface caries, demineralization starts
 Answers: 1-16 41

8. The correct answer is A. The working condyle fracture. If the root is short, a 3-mm apical seal
is rotational, while the nonworking condyle may be considered acceptable.
demonstrates translational movement. As post length increases, retention increases.
However, the relationship is not linear. A post
9. The correct answer is A. Vertical dimension is that is too short will fail, whereas one that is too
a combination of relaxed muscles, lips at rest, long may damage the seal of the root canal fill or
varying freeway space, harmony between lower risk root perforation if the apical third is curved
and middle one-third of the face, ability to speak or tapered. Posts less than 3 mm in length are
without bite rims contacting, tongue room for unacceptable.
making the “th” sound, satisfaction of the pa-
tient’s tactile sense, and a consistent rest position 13. The correct answer is E. All are considerations
measurement. for fabrication of a crown under an existing RPD.

Operative Dentistry and

Since the maxillary plane “appears” close, Path of draw or withdrawal is planning both
and there is light contact near centric rela- guide planes and reciprocal planes surfaces, as

Prosthodontics
tion, face bow is not the error. Remember the well as areas that require survey lines in the gin-
problem is the straining lips to contact each gival third. Location of rests (at least 1mm deep)
other. will help you determine RPD design and eval-
Answer choice C would be true if lips were uate where rest seat will be in new crown. Ori-
contacting “too much,” and there was a lack of entation of guide planes is important because of
harmony with lower and middle one-third of the path of draw. Finally, it would be unesthetic if
face. porcelain were to chip because of the stress from
Freeway space is the space between the oc- retentive metal arms of RPD design.
cluding surfaces of the maxillary and mandibu-
lar teeth when the mandible is in physiologic 14. The correct answer is A. If more than 3 to 4 mm
position. of coronal tooth structure remains, use of a post
in the root for retention is not necessary, and this
10. The correct answer is C. avoids the chance of perforation. Answer choices
B, D, and E are incorrect because more tooth
11. The correct answer is C. The best anterior es- structure is required for a secured core without
thetic will be achieved by using the adjacent a post.
tooth to a space for path of withdrawal because
the contour of the artificial tooth can be ma- 15. The correct answer is B. All patients using re-
nipulated to fit existing natural tooth. Extraction movable prosthodontics should visit his or her
of the remaining anterior teeth may be an op- dentist no less than one time a year, preferably
tion if these remaining teeth are compromised. every 3 months.
Although occlusion with the lower mandibular
teeth is a consideration for esthetics, it is not be- 16. The correct answer is D. Geometry of tooth
cause of its path of draw. All treatment options preparation is a subcategory of retention and re-
should be considered and presented to the pa- sistance form. It is not considered a category
tient. of mechanical consideration. Providing reten-
tion form can be further divided to include (1)
12. The correct answer is D. Most endodontic texts magnitude of the dislodging forces, (2) geome-
advocate maintaining a 5-mm apical seal. Ide- try of the tooth preparation, (3) roughness of the
ally, the post should be as long as possible with- fitting surface of the restoration, (4) materials
out jeopardizing the apical seal or the strength being cemented, and (5) film thickness of the
or integrity of the remaining root structure. luting agent. Providing resistance form can be
If the post is shorter than the coronal height further divided to include (1) magnitude and di-
of the clinical crown of the tooth, the prognosis rection of the dislodging forces, (2) geometry of
is unfavorable. Stress is distributed over a smaller the tooth preparation, and (3) physical properties
surface area and more likely to cause radicular of the luting agent. Preventing deformation of
 42 Chapter 2: Operative Dentistry and Prosthodontics

the restoration can be further divided to include is overprepared. Bevels are rarely indicated ex-
(1) alloy selection, (2) adequate tooth reduction, cept for full-gold crowns, inlay and onlay prepa-
and (3) margin design. rations. Often this type of finish line is used to
relieve a lip when overprepared with a chamfer
17. The correct answer is B. Three to six degrees finish line.
has been shown to have the optimal retention in
crown preparation. One to three degrees is too 21. The correct answer is B.
small a degree of convergence; therefore, a possi-
bility of undercuts exists. Four to eight degrees is
Revised Classification System for Alloys
incorrect because any angle greater than 6 will for Fixed Prosthodontics
undermine retention. Likewise, 6 to 9 degrees
will undermine retention. Classification Requirement
Operative Dentistry and

High noble alloys Noble metal content ≥ 60%

(gold + platinum group∗ )
18. The correct answer is C. Crowns and FPDs are and gold ≥ 40%
Prosthodontics

best fabricated with Type III alloys. Complex in-

lays are best fabricated with Type II alloys. RPDs Titanium and Titanium ≥ 85%
and pinledges are fabricated with Type IV alloys. titanium alloys
Nickel-chromium alloys are stronger than Type Noble alloys Noble metal content ≥ 25%
(gold + platinum group∗ )
IV alloys. Some patients may present with an al- Predominantly Noble metal content < 25%
lergic reaction to nickel-chromium. Simple in- base alloys (gold + platinum group∗ )
lays are best fabricated with Type I alloys. Type
III alloys are used to fabricate Crowns and FPDs.
∗
Metals of the platinum group are platinum, palla-
dium, rhodium, iridium, osmium, and ruthenium.
19. The correct answer is E. When the margin
preparation is taken subgingivally, there is an 22. The correct answer is D. A modified ridge lap
increase in surface area; this in turn increases is recommended in areas of high esthetic con-
retention. Keeping the margin above the gin- cern (i.e., anterior teeth). This design is moder-
gival tissue decreases the complications of tooth ately easy to clean. Pontic design is classified into
preparation. Patients are able to keep the restora- two categories, mucosal contact and no mucosal
tion clean with daily oral hygiene if the margin contact. A modified ridge lap is categorized by
in maintained above the gingival tissue. Impres- mucosal contact.
sion material will have better access to margins Saddle-ridge lap is not recommended pontic
if maintained supragingivally. The clinician will design because its concave fitting surface over-
have direct visual access for evaluation of the laps the residual ridge of missing tooth. This tight
PFM during recall if the margin in maintained fit with the tissue does not allow for adequate hy-
supragingivally. giene and will accumulate plaque causing tissue
inflammation.
20. The correct answer is C. All-ceramic crowns, A conical pontic is easy for the patient to
such as those often used in areas of high esthetic keep clean. It has only one point of contact with
consideration, are best prepared with a shoulder the gingival tissue as the design is convex, heart
finish line. The shoulder finish line is used to shaped. This type of design would be recom-
minimize risk of porcelain fracture. Featheredge mended in the posterior region where esthetics
is usually contraindicated when preparing for ce- is not a high concern.
ramic crowns because of over-contouring of the The sanitary/hygienic design is categorized
crown near the margin. It typically does not pro- by no mucosal contact; therefore it is most
vide sufficient bulk on the restoration, although hygienic. However, with poor esthetics, it is
it is the most conservative type of finish line. typically considered for posterior areas with in-
Chamfer finish lines are best suited for margins creased bone loss. It is the least “toothlike.”
prepared for metal restorations. This type of fin- The modified sanitary is a modification of the
ish line can cause a lip on the margin if the tooth sanitary design, but its archway design between
 Answers: 17-30 43

the abutment teeth allows this design to increase It is also a disadvantage of polyethers, causing ex-
connector size while decreasing the stress to the pansion when contacted with moisture.
pontic.
27. The correct answer is B. A wax pattern is made
23. The correct answer is A. Ferric sulfate and alu- on the die. A sprue is attached to the wax pat-
minum chloride are good hemostatic agents that tern. There is no such spruing step. A sprue is
minimize tissue damage. Zinc chloride causes a cast metal or plastic acting as a channel, con-
tissue necrosis and is no longer used. Potas- necting the casting to a sprue button. Investment
sium aluminum sulfate is less effective than material selected once the choice of alloy is se-
epinephrine. Epinephrine causes vasoconstric- lected. Once the investment of material is in-
tion and should be used with caution especially serted, reaching the wax pattern and has time to
in lacerated tissue. It may cause tachycardia, so set, the wax pattern is eliminated by burn out.

Operative Dentistry and

it is contraindicated in cardiac patients. Finally, the casting send melted alloy into in-
vestment space, producing a replica of the wax

Prosthodontics
24. The correct answer is C. Value is the relative pattern.
lightness/whiteness or darkness/blackness, and
brightness of a color. Hue, value, and chroma 28. The correct answer is B. All ceramic restora-
are the three dimensions of color. Hue is the ac- tions are contraindicated from using R-MGI lut-
tual color. Chroma is the amount of saturation ing agents because of associated risk of fracture.
of the hue. Metamerism is when two objects ap- Low microleakage is an advantage of R-MGIs.
pear to color match under one light source but Fluoride release is an advantage of R-MGIs. Low
not another. solubility is an advantage of R-MGIs. Reduced
sensitivity is an advantage of R-MGIs. Luting
25. The correct answer is B. Erosion (acid ero- agents containing phosphoric acid have a his-
sion) is wear because of chemical means (e.g., tory of postoperative sensitivity such as with zinc
bulimia, GERD). It does not involve bacterial phosphate.
action-producing defects (deep facial and cervi-
cal wedge-shaped depressions). Attrition is nor- 29. The correct answer is A. Since set irreversible
mal wear of occlusal and/or incisal surfaces of hydrocolloid is largely water, it will absorb (im-
opposing teeth during mastication but can turn bibition) and give off (syneresis) liquid causing a
excessive with parafunction. Abrasion is abnor- distortion in the impression. Therefore, the algi-
mal wear because of mechanical process other nate impression should be poured immediately.
than mastication (e.g., toothbrush). Biomechan- Be sure to always follow manufacturer’s instruc-
ical loading forces that lead to flexure fatigue tions.
degradation at a distant location on the tooth
cause abfraction. Bruxism is not a type of wear 30. The correct answer is D. As inflammation de-
but is rather the parafunctional habit of grinding creases, mucosal tissue heals, and bone resorbs
teeth. and remodels. As a result, the I/D may not sup-
port or retain itself on the ridge. This may lead to
26. The correct answer is D. PVS has excellent pain or fracture of the denture. The denture will
surface detail. Along with dimensional stabil- need to be relined or be remade after 6 months.
ity, these are the advantages of using a PVS ma- An immediate denture should never used as
terial for final impressions. Hydrophobicity is a a complete denture. Once time has allowed the
disadvantage of PVS. Polyether’s advantages are tissue to heal properly, a better impression can
low permanent deformation, dimensional sta- be taken to fabricate a complete denture meant
bility second only to PVS, and hydrophilicity. for a use over a longer term. Complete dentures
Temperature sensitivity is a disadvantage of PVS. also will not last forever but are fabricated for
Polyether’s main disadvantage is rigidity during multi-year use.
removal of impression. Latex gloves will retard An immediate denture is used to control in-
PVS setting. Wettability is a disadvantage of PVS. flammation and protect the surgical site from
 44 Chapter 2: Operative Dentistry and Prosthodontics

further trauma that may occur within 1 to 2 days 35. The correct answer is C. Excess VDO is usu-
post oral surgery. In addition, an I/D will aid ally the primary problem that can be corrected
to maintain VDO and a more natural esthetic by resetting the tooth setup to decrease the VDO
while tissue heals. to a more comfortable and stable height. Click-
Depending on the patients healing process, ing is also commonly the result of habit. If the
a year may be too long. Six months is typically problem is habit, this is more difficult to correct.
enough time for bone remodeling to occur in The dentist should refrain from using porcelain
the maxilla and the mandible. teeth.
Check biting is caused by insufficient VDO
31. The correct answer is C. Stability is the resis- and horizontal overlap of posterior teeth. This
tance of the denture base against lateral forces. can be corrected by resetting tooth setup prior
Support is the resistance to the forces directed to processing. The lack of posterior palatal seal
Operative Dentistry and

against the tissues. Retention is the resistance to adaptation may lead to gagging. A reline will be
the dislodgement of the denture base away from required to achieve a proper seal. You may also
Prosthodontics

the tissues. consider the posterior length of the denture if

Temperature should not affect a denture once gagging is a problem and reduce to a comfort-
it has been fabricated. Resiliency and flexibility able length.
are more important fit factors for partial den-
tures. 36. The correct answer is D. The direction of ridge
resorption for the maxilla is superior and poste-
32. The correct answer is B. Studies show that mid- rior, while the mandible is inferior and anterior.
lines up to 2 mm off center are not noticeable This discussion with the patient is important so
unless they become canted obliquely. the patient understands that the denture does
not last forever.
33. The correct answer is C. The semiadjustable
(Class III) articulator provides diagnostic infor- 37. The correct answer is F. All of the answer
mation while minimizing clinical adjustment choices are reasonable actions to be taken with
at the try-in appointment. It simulates condylar this patient. Patient education regarding denture
pathways by using averages or mechanical equiv- care and use is particularly important because
alents for all or part of the motion. Class I articu- without it, the patient will recreate the same mis-
lators are nonadjustable and only accept a single takes in denture care and use.
registration. Class II articulators are also non-
adjustable; however, they accept a horizontal 38. The correct answer is B. The residual ridge is
and vertical registration. Movements are not ori- the primary maxillary area for denture support
ented to the TMJ. Class IV articulators are fully and the buccal shelf is the primary mandibular
adjustable. They accept a three-dimensional dy- area for denture support.
namic registration. These instruments allow for The secondary area for denture support in
orientation of casts to the TMJ and simulation maxilla is rugae. Relief areas are the incisive
of mandibular movements. Class V articulators papilla, prominent midline suture, and areas of
do not exist. the residual ridges that are highly displaceable.
The secondary area for denture support in the
34. The correct answer is B. The ARCON is mandible is the residual ridge. Relief areas are
anatomically correct, which makes the under- the sharp spiny ridges with overlying displace-
standing of mandibular movements easier. The able tissue, mental foramen if exposed by se-
condylar element is in the lower member, and its vere resorption, sharp mylohyoid ridges, tori, and
condylar inclination to maxillary occlusal plane prominent genial tubercles.
angle is fixed. The non-ARCON design has its
condylar elements in its upper member, and its 39. The correct answer is E. Landmarks of the
condylar inclination to maxillary occlusal plane mandible that should be accurately captured are
angle changes as the articulator opens. the residual ridge, labial and lingual frenum,
 Answers: 31-45 45

buccal frenae, buccal shelf areas, external The patient should feel comfortable with the
oblique lines, retromolar pads, lingual sulci, and denture. Teeth should not prematurely contact
retromylohyoid spaces. each other and should not interfere with the pa-
tient’s proprioception.
40. The correct answer is D. The advantages of us- Check the patient’s profile. An increased
ing polysulfide are the long working time, its VDO would cause strained facial expression. A
flexibility, and its tear-resistant properties. Long decreased VDO would cause a drooping at the
setting time, unpleasant odor, and highest per- corners of the mouth and a prognathic appear-
manent deformation are disadvantages of poly- ance.
sulfides. Evaluating and measuring an old denture can
Final impressions are beaded with rope wax be one of the most important tools to determin-
and boxed with boxing wax to create master casts

Operative Dentistry and

ing a patient’s VDO.
with proper land areas along the borders of the
impression and an adequate base. 43. The correct answer is E. The delivery/insertion

Prosthodontics
An interim denture base is fabricated on the appointment is typically the longest because all
master cast to support the occlusal rim. The oc- discrepancies in tissue adaptation, border ex-
clusal rim is made of wax to help with jaw rela- tension, VDO, occlusal harmony, and esthetic
tion records and the setting of the teeth. The rim value must be addressed. When the corrections
is contoured and adjusted in the mouth. are accompanied by patient education and in-
structions, the adaptation should be a pleasant
41. The correct answer is E. Thirty-three to 45 de- learning experience for the patient. It is very
grees is the correct angle for an anatomical poste- important to have a 24-hour follow-up to ad-
rior tooth setup. There are six factors relevant to just undetected errors. Delivery should not be
selection of posterior teeth: (1) occluso-gingival schedule on Friday unless your office is open on
length, (2) mesiodistal width, (3) buccolingual Saturdays.
width, (4) shade, (5) type of occlusal surface, and
(6) material. 44. The correct answer is F. These are all benefits of
The semi-anatomical posterior setup is 10 to resting the oral tissue from the constant contact
20 degrees, while the nonanatomical setup is 0 of the denture on it.
degree. Anatomical setup is used for easier pen-
etration of food, better esthetics, interdigitating 45. The correct answer is D. Rebasing is the replace-
cusps offer a guide for jaw closure, and can be ment of the entire denture base while keeping
ground to harmonize with the TMJ and jaw clo- the same denture teeth in their current occlusal
sure. The nonanatomical set-up is used as a sim- relationship. This option can also be utilized
pler technique requiring less instrumentation. It when the denture base has been fractured or has
is also used when closure is in more than one po- become stained or discolored.
sition and adapts more easily to Class II and III Although the fabrication of new dentures
jaw relationships. would be the best option, especially if dentures
have been used over a long period, personal and
42. The correct answer is E. Parallelism of the resid- economical issues may make this option unrea-
ual ridges is an excellent guide if the ridges sonable.
have not experienced excessive bone resorption. Relining is the replacement of the intact sur-
Once casts have been mounted, the maxillary face of the denture base with a new layer of ma-
and mandibular casts can be evaluated for par- terial to make up for loss of supporting tissue.
allelism, which will aid in VDO approximation. It is important to understand that a visual refer-
The closest speaking space, or 1 mm, is con- ence of the loss of supporting tissue is important
sidered when the patient speaks. Special con- before recommending this treatment option.
sideration should be given to “ch,” “s,” and “j” The use of denture adhesive should never be
sounds. Teeth should not touch during normal the solution to an ill-fitting denture.
conversation.
 46 Chapter 2: Operative Dentistry and Prosthodontics

The maxilla and mandible will continue to retainers, indirect retainers, auxiliary rests, and
resorb, thus causing the denture to become even denture bases.
more unstable over time. The types of maxillary major connectors in-
clude:
46. The correct answer is C. 1. Single posterior palatal bar
Kennedy Class I—Bilateral distal extension 2. Palatal strap
Kennedy Class II—Unilateral distal extension 3. Anterior posterior or double, palatal bar
Kennedy Class III—All tooth supported 4. Horseshoe or U-shaped connector
Kennedy Class IV—Single anterior area 5. Closed horseshoe or anterior posterior palatal
crossing the midline. This classification strap
(IV) cannot have a modification. An easy 6. Complete palatal coverage
Operative Dentistry and

method to determine modification is to

count the number of missing spaces (spans 49. The correct answer is C. A lingual plate and
not teeth) in a single arch and subtract that Kennedy bar will both provide support, such as
Prosthodontics

number by 1. with a splint, to anterior teeth that have lost sup-

port of the bone. They also provide additional
47. The correct answer is E. Applegate’s rule 8 states indirect retention when most, if not all, posterior
that there can be no modification areas in Class teeth are being replaced with the partial denture.
IV arches. The following are Applegate’s rules: Remember that the major connector itself is not
Rule 1—Classifications should always follow an indirect retainer; however, the support given
rather than precede any extractions of teeth that by the rests on the anterior teeth supply indirect
might alter the original classification. retention. Since the bar is contacting all anterior
Rule 2—If a third molar is missing and is not teeth, the force is distributed along the bar to all
to be replaced, it is not considered in the classi- teeth contacted, thus reducing total force on a
fication. Answer B is Rule 4, Answer C is Rule 5, single tooth. The lingual plate should be con-
and Answer D is Rule 6. All are true statements sidered before the Kennedy bar because of food
and therefore the incorrect answers. entrapment between the double bar and tongue
Rule 3—If a third molar is present and is to annoyance with the Kennedy bar.
be used as an abutment, it is considered in the The lingual bar is the most commonly used
classification. major connector. Its advantage is its simplicity
Rule 4—If a second molar is missing and is and its minimal contact of oral tissue.
not to be replaced, it is not considered in the The labial bar is indicated for patients with
classification. severe lingually inclined lower anterior teeth
Rule 5—The most posterior edentulous area and/or premolars where a traditional lingualized
always determines the classification. bar cannot be fabricated. This major connector
Rule 6—Edentulous areas other than those should only be used when absolutely necessary
determining the classification are referred to as and all other options have been exhausted.
modifications and are designated by their num-
ber. 50. The correct answer is C. A retentive clasp is di-
Rule 7—The extent of the modification is not vided into three parts: the proximal, middle, and
considered, only the number of additional eden- terminal. The terminal third is placed beneath
tulous areas. the height of contour, allowing it to engage at
the undercut.
48. The correct answer is D. Answer choices II Although there is a variable amount of flex-
and IV describe minor connector functions. Mi- ibility in the middle part, as the wrought wire
nor connectors connect all the remaining com- transforms from rigid (proximal) to flexible (ter-
ponents of the RPD to the major connector minal), the terminal end is still more flexible.
and provide stress distribution. These remain- The proximal part is the most rigid and is posi-
ing components include clasp assemblies, direct tioned above the height of contour.
 Answers: 46-57 47

51. The correct answer is A. Rigidity, durability, es- restoration. By having the buccal and lingual
thetic, and restorability are not requirements for walls converge occlusally will lock the restora-
clasp design. The six basic requirements for clasp tion in place. Proximal retention locks should be
design are as follows: placed 0.2 mm into the DEJ. Entirely in dentin
1. Retention—provide retention against dis- maintaining enamel support, regardless of the
lodgement axial depth. If the retention locks are placed en-
2. Support—property of clasp to resist displace- tirely into the axial wall, there is no effective re-
ment in a gingival direction tention obtained, and there is the increased risk
3. Stability—resistance to horizontal displace- of pulpal exposure.
ment Beveling or rounding the axiopulpal line an-
4. Reciprocation—to resist horizontal forces ex- gle increases the bulk of and decreases the stress

Operative Dentistry and

erted on the tooth by the retentive arm concentration within the restorative material.
5. Encirclement—each clasp must encircle This aids in the resistance form of the prepa-
ration.

Prosthodontics
more than 180 degrees of the abutment tooth
6. Passivity—for insertion and removal of partial The uninvolved proximal wall should be
denture slightly obtuse (6 degrees) and diverge toward
the occlusal. This will provide adequate sup-
52. The correct answer is C. An indirect retainer port and prevent undermining of the uninvolved
must be rigid. If the retainer were to flex, forces marginal ridge and fracture of the restoration.
would be multiplied instead of dissipated. The The resistance form aids in the resistance of
remaining statements are true regarding indirect the restoration and the tooth to fracture as a re-
retainers. Indirect retainers are most often incor- sult of occlusal forces. The pulpal depth of the
porated when there is a unilateral or bilateral restoration is preferred to be a minimum of 2.0
distal extension. mm as measured from the central fossa and en-
tirely into an even layer of hard dentin.
53. The correct answer is E. After examination, di-
agnosis, and the treatment planning phases, the 57. The correct answer is E. Glass ionomer ce-
sequence of mouth preparation appointments ments are made of a polyacrylic acid liquid and
must be planned with the goal of conserving as an acid-soluble calcium fluoroaluminosilicate
much time as possible. glass powder. Glass ionomer releases fluoride
over a sustained period of time, which aids in
54. The correct answer is C. Kennedy Class IV is a the remineralization of tooth structure and has
single, but bilateral (crossing the midline), eden- been shown in studies to inhibit the progres-
tulous area located anterior to the remaining sion of secondary caries. Glass ionomer bonds
teeth. chemically to tooth structure by having the car-
Kennedy Class I—Bilateral distal extension boxyl groups of the polyacids chelated by the cal-
Kennedy Class II—Unilateral distal extension cium, which is in the apatite of the enamel and
Kennedy Class III—All tooth supported dentin. Enamel has a higher inorganic compo-
Kennedy Class IV—Single anterior area sition than dentin, and thus the bond strength
crossing the midline. This classification to enamel is higher. Calcium hydroxide liners
(IV) does not have a modification. should only be used if the remaining dentin
thickness is less than 0.5 mm. This is done
55. The correct answer is D. Wrought alloy clasps to protect these deep areas from direct contact
are placed in an undercut of 0.020 inch. Chrome with unset glass ionomer. Glass ionomer shows
metal cast clasps are placed in an undercut of mild pulpal effects that tend to subside within
0.010 inch. Golf cast clasps are placed in an un- a month’s time. When glass ionomer cements
dercut of 0.015 inch. are compared with zinc phosphate cements,
glass ionomer cements have shown a lower sol-
56. The correct answer is C. Retention form of the ubility in the environment of the oral cavity.
preparation prevents dislodging of the amalgam Mechanical properties with the exception of a
 48 Chapter 2: Operative Dentistry and Prosthodontics

lower elastic modulus are similar in comparison is very deep and they will provide thermal insu-
as well. lation, thus protecting the pulp. With composite
restorations, a base is not needed for thermal in-
58. The correct answer is B. The setting time is the sulation; however, with small pulpal exposures,
time needed from the start of mixing to the calcium hydroxide is still used for its ability to
time for a material to reach a state of hardness. aid in the formation of secondary dentin bridges.
The penetration test is used to determine the A small amount of calcium hydroxide can be
end point of the reaction. The setting time of placed on a pinpoint exposure and covered with
Gypsum can be manipulated as to increase or a liner (usually, a zinc phosphate) to provide
decrease. The following chart below shows ways pulpal protection. This is a direct pulp cap pro-
to decrease the setting time of Gypsum: cedure. An indirect pulp cap is when a small
amount of carious dentin is left behind and then
Operative Dentistry and

Variable Decrease setting time covered with calcium hydroxide. This procedure
utilizes the antimicrobial properties of calcium
Prosthodontics

P:L ratio By ⇑ P:L ratio, have less liquid

per unit volume at start of hydroxide.
mixing
Rate and time Longer and more rapid the 60. The correct answer is E. Composite restorations
of spatulation plaster is mixed, the shorter should have all internal line angles rounded; this
setting time that can be allows for better banking of the composite mate-
achieved
Contamination If impurities are added to rial. It is easier to place composite into rounded
of P:L mixture, it will decrease the line angles than sharp ones. Remember, sharp
set time; this can be done by internal line angles are needed for retention
the addition of slurry in gold restorations. Micromechanical bonding
water/terra alba. This is the through acid etching provides primary retention
addition of small amounts of
for composite restorations when needed addi-
set Gypsum in watery
mixture tional retention can be obtained. Undercuts can
Temperature Temperature has shown to be made into the gingivo-axial and inciso-axial
have minimal effect; it, lines angles with a small round bur; this will
however, slightly shortens provide a form of mechanical retention. This is
the set time of the reaction usually done for larger carious lesions. The cavo-
surface margins when placed on enamel should
be beveled. This is true as beveling will allow the
59. The correct answer is D. The pulpal depth of an
acid-etch attack to occur at the ends of enamel
amalgam preparation should extend to a mini-
rods, allowing for better adhesion and retention
mum of 0.5 mm into sound dentin. This will aid
of the restorative resin material. Beveling also
in the resistance form of the cavity preparation.
aids in preventing microleakage. Outline form
The ideal remaining amount of dentin to pro-
of the prep is determined by the extent of the car-
vide thermal insulation to the pulp is 2.0 mm. If
ious lesion; this holds true for all restorative ma-
the remaining dentin thickness is less than 2.0
terials. A butt joint is indicated when the prepa-
mm, a base or liner should be used to replace
ration does not end on enamel. This allows for
the destroyed dentin.
increased retention and a better seal when bond-
ZOE (zinc oxide and eugenol) cannot be
ing to cementum or root dentin.
used on restorations where bonding to enamel
or dentin is needed since the eugenol will in- 61. The correct answer is C. A chamfer margin pro-
terfere with the curing phase (polymerization) vides the best support of a cast gold restoration.
of resin-based composites. Picking a desirable A shoulder is used for porcelain jacket and all
base for a deep restoration is required to replace ceramic crowns. A shoulder bevel is used for
the amount of dentin that has been destroyed. A proximal boxes of inlays and occlusal shoulders
base is needed when the restoration to be placed of mandibular three-fourth crowns.
 Answers: 58-72 49

62. The correct answer is D. All of the state- 67. The correct answer is C. Posterior denture teeth
ments are requirements of a good provisional that are set edge to edge can cause cheek bit-
restoration. The restoration must be fabricated of ing. Lip biting after denture fabrication can be
material that prevents the conduction of temper- caused by reduced muscle tone or a large ante-
ature extremes. The temporary restoration must rior horizontal overlap. Tongue biting may be
be made of material and possess contours that the caused by having the denture teeth set too far
patient will be able to clean easily. It is of great lingually. Gagging may be caused by a denture’s
importance that gingival margins of the tempo- posterior palatal seal extended too far poste-
rary not impinge upon the gingival tissues. riorly.

63. The correct answer is C. This patient needs to 68. The correct answer is D. Physiologic dentinal
function and needs a replacement for esthetics; sclerosis is the natural aging process of dentin.

Operative Dentistry and

therefore, no treatment would be appropriate. In Reparative dentin is produced in the pulp cham-
this case, a fixed bridge prosthesis would be a very ber at the lesion site in response to insults such

Prosthodontics
long span over this edentulous gap, which re- as caries, dental procedures, or attrition.
quires sufficient abutments to adequately place The smear layer is any debris, calcific in na-
force and support. In addition, the severe bone ture, produced by reduction or instrumentation
resorption would compromise result of both an of dentin, enamel, or cementum.
FPD and a Maryland bridge. Because of all of
the above, a removable partial denture would be 69. The correct answer is C. Dentin has un-
the best choice in this instance. evenly distributed intertubular and peritubular
dentin and is therefore heterogeneous in nature.
64. The correct answer is A. An anterior posterior Enamel, however, is almost entirely homoge-
palatal bar connector can be used in almost nous in nature.
any maxillary partial denture to attain symme-
try. A palatal palate is a thin broad connector 70. The correct answer is A. Primers contain hy-
that may be used for simple edentulous area and drophilic monomers that have an affinity for
full palatal coverage. A palatal horseshoe-shaped the exposed collagen fibril arrangement and hy-
connector should only be used when a large non- drophobic properties for the copolymerization
operable torus exists. The use of a single palatal with adhesive resins.
bar is limited to tooth borne restorations for bi-
lateral short-span edentulous areas. 71. The correct answer is B. The hydrodynamic the-
ory proposes that when a stimulus causes the slow
65. The correct answer is B. Contact of the tip of fluid movement to become more rapid, nerve
the tongue with the anterior palate and lingual endings in the pulp are deformed, and this is
surfaces of the maxillary teeth produce “T” and interpreted as pain. Stimuli such as tooth prepa-
“D” sounds. “P” and “B” sounds are produced by ration, air drying, and application of cold have
the lips only. “Th” sounds are produced by the been suggested as causes of sudden, rapid move-
tongue protruding slightly between the maxillary ment.
and mandibular anterior teeth.
72. The correct answer is C. Premolars retain
66. The correct answer is D. Calcium chloride ac- sealants best because the patient is older and
celerates the setting time. Rosin facilitates the it is easier to get better isolation for moisture
speed of the reaction and results in a smoother, control to place the sealant. It is harder to
more homogenous product. Resinous balsam is achieve adequate isolation on primary teeth and
used to increase flow and improve mixing prop- in younger patients. Permanent second molars
erties. Oil of cloves is used in preference to are also noted for difficulty of isolation and mois-
eugenol because it reduces burning sensation ture control.
of the soft tissues of the mouth.
 50 Chapter 2: Operative Dentistry and Prosthodontics

73. The correct answer is A. Permanent first mo- 78. The correct answer is B. The labial reduction
lars erupt when the patient is young. It is more should be in two planes (cervical and facial
difficult to get optimal isolation for restoration planes). A minimum of 1.2 mm in required to
placement at this young age. Sealants are rarely create a satisfactory appearance, but 1.5 is pre-
placed on primary first molars and primary sec- ferred. The incisal reduction for a PMF crown is
ond molars. 1.5 to 2.0 mm. The lingual reduction is 1 mm in
excursion if contacts are in metal, but 1.5 mm of
74. The correct answer is C. The size of the bur reduction is necessary if contact is in porcelain.
does not matter in this situation. Heat and pres-
sure are the most common causes of pulp dam- 79. The correct answer is C. A lingual chamfer
age during cavity preparation. The longer the is insufficient in this situation. A full porcelain
cutting time, the more heat is generated, and restoration will require a shoulder margin. Ade-
Operative Dentistry and

the more damage can be caused. Greater tooth quate reduction is imperative for an all-ceramic
reduction would lead a cavity preparation to be restoration. The facial surface requires a two-
Prosthodontics

closer in proximity to the pulp. Proximity to the plane anatomical reduction of 1-mm depth. The
pulp chamber increases the potential for pulpal incisal edge requires 1.5-mm reduction in inter-
damage. cuspation and excursive movements. The lin-
gual surface of the tooth must be reduced 1.0
75. The correct answer is B. Class II classification is mm to provide adequate relief for porcelain cov-
for interproximal lesions on posterior teeth only. erage
Cavity Classes I, V, and VI can involve both an-
terior and posterior teeth. 80. The correct answer is D. Age is not an abso-
lute contraindication for implant placement or
76. The correct answer is D. A shoulder margin restoration. Patients with acute or terminal ill-
is unnecessary for a full metal crown; a cham- ness are not candidates for implant placement.
fer margin is sufficient. The use of depth cuts Patients with unrealistic expectations, poor mo-
along anatomical planes of the occlusal surface tivation, or poor oral hygiene are not sound can-
will ensure adequate reduction and prevent over- didates for implants placement. Elective dental
reduction. The final preparation of the occlusal work on pregnant patients is not indicated. Im-
surface should follow a similar anatomical con- plant placement in patients who have received
tour of the crown prior to reduction. Axial re- IV bisphosphonates or head and neck radiation
duction should be approximately 6 degrees and is relatively contraindicated because of the risks
should be slightly convergent to provide the max- of bisphosphonate-related necrosis and osteora-
imum retention for the restoration. Increased dionecrosis, respectively.
taper results in excessive reduction of tooth struc-
ture. The use of PFM or partial ceramic cov- 81. The correct answer is B. The extent of caries
erage in nonesthetic areas will preserve tooth is important because that is all that needs to be
structure. removed without removing sound tooth struc-
ture. Removing sound tooth structure is unnec-
77. The correct answer is B. The recommended di- essary when performing a composite restoration,
mensions for a complete cast crown are a mini- and doing so would not produce the most
mum of 1-mm clearance on nonfunctional cusps optimal preparation. A composite restoration
and 1.5 mm on functional cusps. The functional does not require mechanical retention. The
cusp bevel must be at a flatter angle than the cus- preparation does not correspond with the tooth
pal plane to provide adequate reduction, which shade.
should be placed at about 45 degrees to the long
axis of the tooth. A chamfer margin on a full 82. The correct answer is D. The polymer matrix
metal crown allows for a 0.5-mm metal thick- is the phase to which the other ingredients get
ness, which provides adequate strength for the added. The filler particles are silicon dioxide or
restoration. glass that improves the physical properties of the
 Answers: 73-91 51

matrix. The coupling agent assists in the adhe- properties than those in dentin; the mineral con-
sion of the matrix to the filler particles. The ini- tent in dentin is relatively sparse and arranged in
tiator is what allows the polymerization of the a more tubular structure, allowing for more rapid
composite to be activated. progression of caries (answer D).

83. The correct answer is D. 1.5 mm is the proper 87. The correct answer is A. Actinomyces visco-
amount of reduction because 0.3 to 0.5 tooth sus is the most common cariogenic bacteria in
structure reduction is needed to accommodate root surface or smooth surface caries (answer
the metal and an additional 1.0 mm is needed for B). Streptococcus sanguis is the earliest organ-
the porcelain. 0.8 and 1.0 mm are not enough re- ism found in dental plaque (answer C). A good
duction to accommodate both metal and porce- way to remember common cariogenic bacte-
lain. 2.5 mm is too much reduction. ria: SALIVA: S. mutans, sanguis. A. viscosus.

Operative Dentistry and

Lactobacilli. Veillonella. A. naeslundii.
84. The correct answer is A. Gold is a strong ma-

Prosthodontics
terial. As opposed to other materials, gold rarely 88. The correct answer is C. The four zones of in-
fractures. When used in restorations, it has the cipient lesions are listed above in correct order
greatest functional longevity. Gold esthetics are A to D. These characterize separate zones seen
inferior to other materials as gold does not look in a sectioned enamel lesion. The translucent
like natural teeth. The impression material used zone is the deepest zone and is named for its ab-
is dictated by the operator, not the restoration. sent or composition-less appearance seen under
Gold has a wear rate that is actually similar to polarized light. The dark zone represents rem-
enamel. Gold, unlike porcelain, will not cause ineralization and is named after its characteristic
wear on the opposing teeth to be accelerated inability to transit polarized light. The body zone
is the largest zone and represents a demineral-
85. The correct answer is B. It is important to know ization phase. The surface zone is the outermost
which restoration is going to be the best for the zone and seems to be unaffected by the caries.
specific tooth, and depending on the amount
of remaining tooth structure, if a post will be 89. The correct answer is D. Rampant caries are
necessary. The canal configuration is not going rapidly progressing and widespread caries. They
to affect the final outcome of how the tooth is are often the result of histological disadvan-
restored. The function of the restored tooth is tages, poor hygiene, drug abuse, radiation, high
not one of the first things to be considered. sugar diets, or disadvantaged saliva. They present
acutely (A), are most often associated with pain
86. The correct answer is C. Frank Caries describe (E), are seen in children (C), and result in large
caries that have progressed just into the denti- cavitation because of its deep and narrow pre-
noenamel junction (DEJ). Carious lesions oc- sentation.
cur when a mass of bacteria adhere to the tooth
surface forming a dental plaque. The plaque bac- 90. The correct answer is E. While all of the above
teria feast on refined carbohydrates, metabolize are known risk factors for caries, A and B are
the sugars, and produce acidic byproducts. The high-risk factors, B and C are moderate-risk fac-
acid lowers the pH of the plaque adherent to the tors. Other high-risk factors for caries include
tooth; when the pH drops to 5.5, demineraliza- visible plaque, frequent between meals snacks,
tion begins to take place; this is known as the inadequate saliva, and dental appliances.
critical pH (answer A). Early lesions are capa- Moderate-risk factors include: interproximal
ble of remineralization or arrest if the pH is in enamel lesions, other white spots or discol-
favor of building and mineral content like fluo- orations, and recreational drug use.
ride is abundant. Incipient caries describe caries
that have not progressed farther than enamel; 91. The correct answers is D. Autogenous graft.
these are reversible and capable of remineraliza- Xenograft and alloplastic grafts are only osteo-
tion (answer B). Caries in enamel have different conductive and will not grow new bone without
 52 Chapter 2: Operative Dentistry and Prosthodontics

the presence of surrounding cells, such as os- 94. The correct answer is D. The first statement is
teoblasts, that will form bone. They only act as a FALSE and the second statement is TRUE.
scaffold to which new bone can be added onto. Defects in color vision primarily affect 8%
Allografts can be osteoconductive and os- to 10% of the MALE population, for example,
teoinductive, meaning that they act as a scaf- about 10% of all males are color blind.
fold onto which new bone forms and their bone The second statement is TRUE. Achroma-
matrix contains inducing agents that cause new tism is the complete lack of hue sensitivity.
bone to form. Dichromatism is sensitivity to two of the primary
Only autogenous bone is osteoconductive, os- hues. Anomalous trichromatism is sensitivity to
teoinductive, and osteogenic, meaning in addi- all three primary hues with a deficiency or ab-
tion to acting as a scaffold for new bone to adhere normality of one of the three primary pigments
to and having a matrix with inducing agents to in the retinal cones.
Operative Dentistry and

stimulate new bone, it also has the capability of

forming new bone on its own, without the aid of 95. The correct answer is C. Ovate pontic.
Prosthodontics

surrounding growth factors. Sanitary (hygienic) pontics have the best ac-
cess for oral hygiene but usually provide you with
92. The correct answer is B. Fentanyl. the worst esthetic outcomes once the gingival tis-
Triazolam, lorazepam, and diazepam are all sues have healed.
benzodiazepines that can be delivered by an oral Conical pontics typically provide for good ac-
route and are routinely used for oral conscious cess for oral hygiene but again tend to have poor
sedation. esthetic outcomes with the final prosthesis
Fentanyl is considered to be an IV drug used Modified ridge lap pontics are moderately
in IV sedation easy to clean and can provide good esthetics.
Ovate pontics: generally accepted to provide
93. The correct answer is A. Both the statement and the best esthetics for the final prosthesis because
the reason are correct and related. of its support of the gingival architecture around
Taken straight from advantages of single tooth the extraction site following healing.
implants section of the “Contemporary Implant
Dentistry” textbook by Dr. Carl Misch, 3rd edi-
tion.