FINAL IMPRESSION FOR

COMPLETELY EDENTULOUS
PATIENTS

T HE OUTLINE
INTRODUCTION .
 DEFINITIONS
 OBJECTIVES .
 ANATOMICAL LANDMARKS .
 THEORIES OF IMPRESSION .
 IMPRESSION TECHNIQUES.
 IMPRESSION MATERIALS .
 PROCEDURES FOR FINAL IMPRESSION RECORDING :
 Checking and correcting the custom tray.
 Border molding the custom tray.
 Making final impression.
 Pouring the master cast.
 SPECIAL IMPRESSION TECHNIQUES
 NAUSEA DURING IMPRESSION MAKING .
 CONCLUSION .
 REFERENCES .
INTRODUCTION

 Impression making is an ART.

 It requires certain amount of skill and proper
knowledge of the anatomy of oral cavity.

 The final impression is one of interdependent

procedures , Inadequacy in any will affect the following.
“Ideal impression must be in the mind
of the dentist before it is in his hand.
He must literally make the impression
rather than take it”
M.M. Devan
DEFINITIONS
IMPRESSION
A negative likeness or copy of the surface of an
object . – gpt 8

FINAL IMPRESSION
The impression that represents the completion of
the registration of the surface or object. (– gp)

A final impression is an impression for making the

master cast .
OBJECTIVES IN IMPRESSION MAKING
ANATOMICAL LANDMARKS
ACCORDING TO THE CLINICAL SIGNIFICANCE

Landmarks
of edentulous
jaws

Limiting Supporting
Relief areas
structures structures
ANATOMICAL LANDMARKS OF THE
MAXILLA
LIMITING STRUCTURES

 LABIAL FRENUM
 LABIAL VESTIBULE

 BUCCAL FRENUM

 BUCCAL VESTIBULE

 HAMULAR NOTCH

 POSTERIOR PALATAL SEAL AREA

 LABIAL FRENUM

 It is a fold of mucous membrane

at the median line
 No muscle attachment

 Sufficient allowance should be

created in final impression and
in complete denture prosthesis
 If the frenum is attached close
to the crest frenectomy should
be done
 The labial notch of the denture
should be narrow but deep
enough to avoid interference
 LABIAL VESTIBULE

 This anterior region of maxillary basal

seat extends from one buccal frenum to
the other on the labial side.
 The major muscle in this area is
orbicularis oris.

 Three objectives are apparent:

1) The impression must supply sufficient
support to the upper lip to restore the
relaxed contour.
2) The labial flange of the impression must
have sufficient height to reach the
reflecting mucous membrane of the
labial vestibular space.
3) There must be no interference of the
labial flange with the action of lip in
function.
 BUCCAL FRENUM

 Forms the dividing line between

the labial and buccal vestibules.
 The frena may be a single or
double fold or even a broad-fan
shape.
 The levator anguli oris muscle
attaches beneath the frenum
 The orbicularis oris pulls the
frenum forward
 The buccinator pulls it backward.
 Thus it requires more clearance
for its action than the labial
frenum does.
 BUCCAL VESTIBULE

 Extends from the buccal

frenum to the hamular notch.

 The size and shape of the

distal end of the buccal flange
of the denture must be
adjusted to the coronoid
process of the mandible and to
the masseter muscle.
 HAMULAR NOTCH

 Distal limit of the buccal vestibule.

 Depression between maxillary
tuberosity and the hamulus of the
medial pterygoid plate.
 The denture border should extend
till hamular notch.
 Aids in achieving posterior palatal
seal area.
 Over extension cause soreness
 POSTERIOR PALATAL SEAL AREA
“The soft tissue at or along the junction of the soft and hard
palate on which the pressure with in the physiological limits of
the tissue can be applied by a denture to aid in the retention of
the denture.” -GPT.

Made of two regions:

 Pterygomaxillary seal
 Posterior palatal seal
 VIBRATING LINE
 “THE IMAGINARY LINE ACROSS THE POSTERIOR PART
OF THE PALATE MAKING THE DIVISION BETWEEN THE
MOVABLE AND IMMOVABLE TISSUES OF THE SOFT
PALATE WHICH CAN BE IDENTIFIED WHEN THE
MOVABLE TISSUES ARE MOVING”-GPT
 SUPPORTING STRUCTURES

Primary stress Secondary stress

bearing area bearing area

o HARD PALATE. o RUGAE.

o RESIDUAL ALVEOLAR RIDGE o Lateral slopes of the ridge.
o MAXILLARY TUBOROSITIES.
 HARD PALATE

 Covered by keratinized
stratified squamous
epithelium

 The horizental portion of

the hard palate provides
the primary stress-bearing
area.
 RESIDUAL ALVEOLAR RIDGE

 The portion of the residual

bone , soft tissue covering
that remains after the
removal of teeth .

 It is primary stress bearing

area.
 It is the foundation of the
denture.
 MAXILLARY TUBOROSITIES

 It is the distal aspects of the

posterior ridge terminating in the
hamular notch.

 Maxillary denture base should cover

the tuberosities and fill the hamular
notches.

 Gross enlargement(fibrous or bony) surgical correction.

 RUGAE

 These are irregularly shaped ridges of dense connective

in the anterior part of the hard palate.
 Set at an angle to residual ridge & covered by thin soft
tissues.
 It is considered as a secondary stress bearing area.

 Should not be distorted in the impression.

RELIEF AREAS
These are the areas which either :
 Resorb under constant load.

 Have fragile structures within.

 Covered by thin mucosa which can be easily traumatized

& hence should be relieved.

 INCISIVE PAPILLA
 MEDIAN PALATAL RAPHE

 BONY PROMINENCES
 INCISIVE PAPILLA

 Incisive papilla is a mass of

fibrous tissue about 1cm
behind the upper incisors.
 It is an exit point of
nasopalatine nerves and
vessels
 Denture base should be
relieved over the area to
avoid pressure to the
nerves & blood vessels.
 MEDIAN PALATINE RAPHE

 Extends from incisive

papilla to distal end of hard
palate.

 In the region of median

palatal suture , the sub
mucosa is extremely thin ;
so relief should be provided
to avoid trauma or rocking
of the denture.
A-Median palatine raphe
B- Fovea Palatina
ANATOMICAL LANDMARKS OF THE
MANDIBLE
LIMITING STRUCTURES

 Labial frenum
 Labial vestibule

 Buccal frenum

 Buccal vestibule

 Lingual frenum

 Alveolingual sulcus

 Retromolar pad

 Pterygomandibular raphe
 Labial frenum

 Shorter and wider than the

maxillary frenum.
 Frenum contains fiber of
Orbicularis oris and Mentalis
muscle.
 Unlike in maxilla, this frenum
is active
 The denture must be fitted
carefully around it to maintain
a seal without causing
soreness.
 Labial vestibule

 Extends from the labial

frenum to the buccal
frenum.

 The mentalis muscle

inserts very close to the
crest of the ridge in this
area and limits the border
extension in length and
width.
 Buccal frenum

 The buccal frenum forms

the dividing line between
the labial and buccal
vestibule.
 Frenum may be single or
double, broad U shaped or
sharp V shaped.
 It should be relieved to
prevent displacement of
the denture during
function.
 Buccal vestibule

 Extend from buccal frenum to

retromolar pad
 The extent of buccal vestibule
is influenced by the buccinator
muscle, which extends from
the modiolus anteriorly to the
pterygomandibular raphe
posteriorly
 The impression is widest in
this region.
 Lingual frenum

 Fold of mucous membrane.

 The anterior region of the

lingual flange is called sub-
lingual crescent area.

 A high frenum is called as

Tongue tie, it should be
corrected if it affects the
stability of the denture.
Alveololingual sulcus
 Alveolingual sulcus
 Space between the residual ridge & tongue .
 Extends from lingual frenum to retromylohyoid
curtain .
 3 regions (anterior, middle & posterior)

 The anterior region extends from the lingual f. back

to where mylohyoid muscle curves above the level of
the sulcus. (premylohyoid fossa) .
 The middle region
extends from premylohyoid fossa to the distal end of the
mylohyoid ridge, curving medially from the body of the
mandible. This curvature is caused by the prominance
of mylohyoid ridge & the action of mylohyoid muscle.
 The posterior region

 The flange deviates

towards the ridge into the
retromylohyoid fossa.
 Proper recording gives
typical S –form of the
lingual flange.
 The posterior limit of the
mandibular denture is
determined mainly by the
palatoglossus muscle.
 Retromolar pad

 Triangular area of thick mucosa is

found distal to the last molar,
basically on the crest of the ridge.
 This pad is extremely important
in denture construction from
both a denture extension and
plane of occlusion standpoint.
 The retromolar pads should be
covered by the denture, and the
plane of occlusion is generally
located at the level of the middle
to upper-third of this pad.
 Pterygomandibular raphe

 Extending from the hamulus

above to the area of the
retromolar pad below.
 It is often visible in the
maxillary impression and,
when present, is an excellent
landmark for determining the
distal extent of the maxillary
denture.
 It is usually insignificant
when making the mandibular
impression.
 SUPPORTING STRUCTURES

 Primary stress bearing area

• Buccal shelf area

• Pear shaped retromolar pad

 Secondary stress bearing area

• Residual alveolar ridge

 Buccal shelf area

 it is the primary stress-bearing

area of the mandibular arch.
 Boundries :
• Medial side : crest of the ridge,
• Lateral side : external oblique
ridge,
• Mesial area: buccal frenulum,
• Distal side: masseter muscle.
 The buccal shelf consists
primarily of thick cortical bone
& it lies at right angles to
vertical occlusal forces.
 Residual alveolar ridge
 The crest of the residual
alveolar ridge is covered by
fibrous connective tissue.
 The bone at the crest of the
ridge is fenestrated and
consists of thin cortical bone
overlying more cancellous
bone.
 Because underlying bone is
often cancellous , the crest of
the residual ridge may not be
favorable as the primary
stress-bearing area for a
lower denture.
RELIEF AREAS

 Mental foramen(with flat ridge)

 Genial tubercle
 Sharp mylohyoid ridge
 Mandibular tori.
 Sharp bony prominences.
 Crest of knife edge ridge.
 Mental foramen

 As resorption takes place,

the mental foramen will
come to lie closer to the
crest of the ridge.
 The mental nerve and
blood vessels may be
compressed by denture
base unless relief is
provided.
 Pressure on mental nerve
can cause numbness of
lower lip.
 Genial tubercle

 The genial tubercle are a pair of

dense prominences at the
inferior border of the mandible
at the lingual midline.
 They represents the muscle
attachment of the genioglossus
and geniohyoid muscles.
 They only become relevant in
the denture when there is
excessive resorption of the
residual ridge. (A) Residual ridge,
(B) genial tubercles
 Sharp mylohyoid ridge

 The mylohyoid ridge is a

bony prominence along the
lingual aspect of the
mandible.

 The mucous membrane

overlying the sharp or
irregular mylohyoid ridge
needs to be relieved.
 Mandibular tori

 Mandibular tori are lingual

bilateral prominences of
cortical bone in the
premolar area.

 small tori may only require

relief in the denture.

 Large tori require removal

before a denture can be
fabricated.
 Depending
on the
theories of
impression
making.

Depending
on the Depending
purpose of Classification on the
the of impressions technique
impression

Depending
on the tray
type
THEORIES OF IMPRESSION

 Mucostatic (Minimal pressure)

impression theory.
 Mucocompressive (Definite pressure)
impression theory.
 Selective pressure impression theory.
Mucostatic (Minimal pressure) theory
 Harry Page gave the concept of mucostatic based on
Pascal’s law.
 The impression is made with the oral mucous
membrane and the jaws in a normal, relaxed
condition.
 The tray must be spaced or perforated.

 The suitable material is plaster impression or

alginate.
 Retention is mainly due to interfacial surface tension.

 The mucostatic technique results in a denture, which

is closely adapted to the mucosa of the denture-
bearing area .
 Advantages :
1. High regard for tissue health
2. Minimal interference with the blood supply.
pressure Bone resorption

3. This technique is useful in impressions of flabby and

sharp or thin ridges.

 Disadvantages :
1. Neglects the wider distribution of masticatory forces.
2. The completed denture may not fit the mucosa at all
times (uneven distribution of load during mastication ).
 Mucocompressive (Definite pressure)
theory
 The assumption that denture retention is tested most
severely during mastication, many dentists formerly
considered it essential for the tissue to remain in contact
with the denture during chewing.
 Records the oral tissues in a functional and displaced
form.
 Tray must be closely fitted with occlusal rim.

 The suitable material is zinc oxide euogenol

or compound impression with zinc oxide or plaster as a

wash .
 The oral soft tissues are resilient and thus tend to return
to their anatomical position once the forces are relieved.
 (a) the difference in the shape of
the mucosal surface produced by a
mucostatic technique (dotted line)
and a mucodisplacive technique
(continuous line).
 (b) the impression surface,
obtained by a mucodisplacive
technique, fits the mucosa closely
when the denture is under occlusal
load;
 (c) when the occlusal load is
removed the mucosa returns to its
resting shape and the denture
ceases to fit accurately.
 Advantages:
1. Permits the patient to exert his own masticatory force on the
impression material during setting.
2. The natural movements exerted by the patient will conform the
impression material to the anatomic limitations of the mouth.
3. Permits adequate lingual border molding of the impression
“tongue movements are more forceful”.

 Disadvantages :
1. Dentures made by this technique tend to get displaced due to
the tissue rebound at rest.
2. Excess pressure could lead to increase alveolar bone
resorption.
3. Pressure on sharp bony ridges results in pain.
4. Tissues displaced under biting forces may become permanently
deformed and unable to maintain their original form.
 Functional Dynamic
impression
 For patients having existing complete dentures.

 Tissue conditioners are of great help in not only restoring

the tissue health but also, reproducing the tissue details for
a good final impression.
 Technique

 Trim the existing dentures to obtain space for tissue

conditioner.

 Mix 1.5 parts of powder and 1 part of liquid in a glass bottle

for 5 s. Pour the mix on a mixing pad and spread it with a
spatula for 10 s to remove air bubbles.
 While retracting the patient's lip, seat the tray in the mouth
with a rather firm pressure. Mold the borders by digitally
manipulating the cheek and lip tissues in one step.

 Permit patient a few minutes (5 min) to test alignment and

material to flow, then remove denture, rinse with cold water
and determine remaining pressure points that require further
relief. Add material where necessary and repeat the previous
step .

 Now dentures can be given to the patient. Dismiss the patient

for 24 hours with the proper home care instructions given for
the material.
 At the next appointment the patient should be evaluated for
healthy mucosa and well rounded peripheral borders of the
denture.

 A functional impression will result from which the model can

be poured .
Advantages :

 time saving.
 yielding accurate details.

 Functional border molding .

 Particularly useful in geriatric patients, old

denture wearers, replacement of ill fitting
dentures.
Selective pressure impression theory.
 Proposed by Boucher.

 Combines the principles of both pressure and minimal

pressure techniques.
 Forces only on stress bearing area.

 Design of the special tray:

The non stress-bearing areas are relieved.

The stress-bearing areas are allowed to come in contact
with the tray.
 The suitable material is zinc oxide euogenol.
 PHILOSOPHY OF THE SELECTIVE PRESSURE
TECHNIQUE
 Certain areas of the maxilla and mandible, are by nature
better adapted for withstanding extra loads from the
forces of mastication.

 In this technique idea of tissue preservation is combined

with mechanical factor of achieving retention, through
minimum pressure which is within physiologic limits of
tissue tolerance.
 Advantages :
Technique considers the physiologic functions of the
tissues of the basal seat, therefore appears more sound.

 Disadvantages :
1. Some feel that it is impossible to record areas with
varying pressure.
2. Since some areas are still recorded under functional
load, the denture still faces the potential danger of
rebounding and loosing retention
IMPRESSION PROCEDURES FOR FLABBY RIDGES

 OPEN WINDOW TECHNIQUE

 SELECTIVE PRESSURE BY RELIEF OF COMPOUND
IMPRESSION.
 OPEN WINDOW TECHNIQUE

 A primary impression is made and

a cast is poured.

 An indelible pencil is used to

outline the unsupported movable
tissue.

 A single custom tray is made, and

an opening is cut in the tray as
indicated by the transfer of
indelible pencil line.
 The tray is adjusted in the
mouth, and a routine border
molding is formed.

 Wash impression with ZOE paste.

 An impression of the displaceable mucosa is then
recorded by applying or syringing a thin mix of
impression plaster or light-bodied silicone.
 Selective Pressure Impression by relief
 A preliminary compound impression is made .

 The compound is then scraped over the out line of

the flabby ridge .

 Plaster impression material or zinc oxide eugenol

paste are used as awash impression .

 Plaster and zinc oxide records the relieved areas with

minimal pressure where other areas are recorded
under considerable pressure.
A- Scraping the compound selectively. B- Secondary impression in Zn/O eugenol
or plaster.
 IMPRESSION TECHNIQUE FOR
SHARP KNIFE EDGE RIDGES
 The mandibular primary impression alginate in a stock
tray.
 The primary cast is poured and a tray devoid of spacer or
relief wax is fabricated.
 A window is cut in the tray using a straight bur outlining
the marked area, corresponding to the crest of the ridge.
 The tray is then seated onto the cast, and softened
modelling wax is placed into the window, shaped to form a
handle.
 The tray is seated in mouth labial
and lingual borders are border
molded with putty.
 The borders of the impression are
trimmed by 0.5 mm
 The wax handle is removed and
the putty material over the
window is cut out.
 Light-body elastomeric impression
material is loaded into the tray,
which is then seated on the ridge.
 Additional light-body material is then expressed into
the window.
 Lingual and facial borders are molded, ensuring the
tray remains steady until the impression material
sets.
IMPRESSION TECHNIQUES
 Open mouth technique

 Impressions are made with a tray that is

held by the dentist.

 The impression is made while the mouth is

opened .

 Preferred because the operator can see

whether muscle trimming is done properly.
 Closed mouth technique
 Supporting tissues are recorded in a
functional relationship

 Wax occlusion rims that are made on

preliminary casts.

 The patient can manipulate his tissues

by closing, sucking and swallowing to
form peripheral borders.

 Tongue movements are more forceful

when teeth are together.
 Advantage :
1. Permits the patient to exert his own masticatory force on
the impression material during setting.
2. The natural movements exerted by the patient will conform
the impression material to the anatomic limitations of the
mouth.
3. Permits adequate lingual border molding of the impression
“tongue movements are more forceful”.
4. Saving time.

 Disadvantage :
1. Tendency for over extensions or under extensions.
2. No control over the amount of pressure.
3. Soft tissues – displaced- rebound.
4. Bone resoption
IMPRESSION MATERIALS
 Classification
 Elastic
1. Reversible hydrocolloid
2. Irreversible hydrocolloid
3. Rubber impression materials
a. Polyether
b. Silicone

 Non-elastic
1. Gypsum products
2. Metallic oxide pastes(ZOE).
3. Impression compound
 IDEAL REQUIREMENT OF IMPRESSION
MATERIAL

I. Factors affecting accuracy:

 High flow to record the dental arch accurately.
 Dimensional accurate during setting to retain the recorded
dimensions. [i.e. No expansion or contraction]
 Flexible after setting to be removed easily from the mouth.

 Adhesive to the tray upon removal after setting.

 Resistant to tearing or fracture upon removal from the

patient’s mouth.
 Can be disinfected without loss of accuracy.

 Dimensional stable during storage until pouring the model.

 Compatible with model materials

II. Other factors:

1.Acceptable for the patient:

- Non toxic , non irritant, tasteless & odorless.
2. Good handling property:
-Easy to mix or prepare with minimum equipment.
-Viscous enough in order not to flow out of the tray.
-Adequate working time for loading & insertion the tray
with the impression material.
3.Adequate shelf life.
4. Reasonable cost.
 Impression Plaster
 used as a “mucostatic” impression material for making final
impressions.

PROPERTIES
1. Excellent at recording fine detail (because
very fluid when inserted in mouth)
2. Dimensionally stable if anti expansion
solution used
3. Fractures if undercuts present
4. Needs to be treated with a separating
medium (e.g. varnish or soap solution)
before being cast in stone or plaster
5. Exothermic setting reaction
6. Non toxic but may be unpleasant due to
dryness and heat evolved during setting
7. Susceptible to excess saliva.
 ADVANTAGES
1. Good surface detail
2. Excellent dimensional stability
3. Rate of the setting reaction can be controlled by the
clinician
DISADVANTAGES
1. Very rigid – often need to be fractured when
removed from the mouth.
2. Fractures if undercuts are present
3. Properties affected by operator handling technique
4. Taste and roughness may cause the patient to vomit

„History „: exothermic, breaks, non convenient…

 Zinc Oxide Eugenol (ZOE)
Impression Paste
 Applications
• Mainly used for final impressions of edentulous ridges with minor
or no undercuts.
• As a wash impression with other impression materials, such as
impression compound.
• As an occlusal registration material.
• As a temporary liner material for dentures.
• As a surgical dressing.
 Properties
• Good consistency and flow.
• Rigid when set.
• Non toxic
• Adherence to tissues
• Mucostatic or mucocodisplacive
• Good surface details.
• Good dimensional stability
MANIPULATION:
 Mixing is done on an oil-impervious paper or glass slab.
 Two ropes of paste of same length and width, are squeezed on mixing
slab.
 A stiff stainless steel spatula is used for mixing.
 Mixing is done for 30-40 sec until no color streaks in the mix are seen &
a uniform consistency is obtained.
 The mix is then transferred to the impression tray .
 Advantages:
1. It has enough working time to complete border moulding.
2. It can be checked in mouth repeatedly without deforming.
3. It registers accurate surface details.
4. It is dimensionally stable.
5. Does not require separating media since it does not stick
to cast material.

Disadvantages:
1. Requires special tray for impression making.
2. Cannot be used in very deep undercuts
3. Sticky in nature and adheres to tissues.
4. Burning sensation of eugenol causes tissue irritation.
Indications
1. As final wash material (with selective pressure
impression technique).
2. In cases having pronounced nausea.
3. With mucocompressive impression technique.
4. Excessive salivation: zinc oxide is not washed away by
copious saliva ”suitable for lower imp.”

Contraindications
1. Cannot be used in deep undercuts.
2. Eugenol allergy in some patients.
3. In case of dry mouth (xerostomia) because it is sticky
in nature and adheres to tissues.
 Rubber base impression materials
 Excellent elastic recovery.
 Excellent dimensional stability.

 A wide range of viscosities

 A wide range of working and setting times.

 They are clean and easy to handle.

 Non-adherence to dry mucosa.

 Can be classified into:

1) polysulfide
2) condensation polymerizing silicones
3) addition polymerizing silicon
4) polyether
 Polysulfide rubber
Properties
 Elastic recovery is moderate
 Flexibility high, more flexible than all other elastomers.

 Highest tear strength among elastomers

 Flow rates moderate to high

Advantages Disadvantages
 Long working time.  Unpleasant odor.
 Good flow before setting.  Stains cloths.
 Good surface reproduction.  Needs a custom tray to avoid
 High flexibility, easy removal distortion.
from undercuts.  May flow down patient’s throat
 Cheaper than silicones and because of its low viscosity.
polyether.  Must be poured within 1 hr;
low dimensional stability.
 Condensation silicones
Properties
 Elastic recovery is high
 Flow rates low, lower than polysulfides

 Stiffer than polysulfides

 Tear strength is low to moderate

 High polymerization shrinkage can be offset by using a two-

step putty-wash technique
Advantages Disadvantages
 Well accepted by the patients  Must be poured within 1 hr
 High elasticity because it may distort as a
result of shrinkage
 The putty-wash method
eliminates the need for a  Hydrophobic in nature, requires
custom tray a dry field, and is difficult to
pour in stone
 Addition silicones
Properties
 Elastic recovery is excellent.
 Flow rates very low
 Low dimensional changes.
 Have greater rigidity, so are removed with difficulty from
undercuts.
 Tear strength, low to moderate; comparable to condensation
silicones but still less than polysulfides.
Advantages Disadvantages
 Highly accurate.  More rigid than condensation silicones.
 High elasticity.  May release hydrogen, causing
 Pleasant taste, odor, colors. imperfections in the stone cast;
delay pour for 1 hr.
 May be poured 1 week after
making the impression.  Hydrophobic in nature.
 Multiple pours possible.  Latex gloves can inhibit
polymerization.
 Can be used with both stock
and custom trays.  Expensive.
 Polyether
Properties
 Elastic recovery moderate.
 Minimum shrinkage, 0.3% in 24 hr; gives high accuracy, but
inferior to some addition silicones.
 Flow rates are very low.
 Stiffness is high, difficult to remove from the mouth and to separate
from the cast.
 Low tear strength values.
Advantages Disadvantages
 Easy to handle and to mix  Short working and setting times.
 More accurate than  Material is stiff after setting, least
polysulfides and condensation flexible of all elastomers.
silicones  Bitter taste objectionable to
 Good surface reproduction patients.
 Easily poured in stone;  May distort if stored in humidity
 if kept dry, can stay for 1 week or water.
without dimensional changes  Expensive
PROCEDURES FOR FINAL IMPRESSION
RECORDING

 Checking and correcting the custom tray.

 Border molding the custom tray.
 Making final impression.
 Pouring the master cast.
 Checking and correcting the custom tray

Borders of the tray approximately 2 mm The borders of the tray are impinging
above the depth of the vestibule on the movable tissues intraorally and
must be shortened.
The buccal and labial flanges of the The vibrating line has been identified at
impression tray have been shortened the midline and is marked .
sufficiently to create adequate space for
the border molding material.
The posterior extent of the impression tray
is shortened to coincide with the vibrating line.
For most patients, the labial and lingual The impression tray should show a
flange lengths will be of equal length smooth continuous decrease in flange
length as it continues from the buccal
to the crest of the ridge.
The lingual flange of the tray should resemble a smooth
continuous line beginning at the level of the labial
flange in the anterior and gradually increasing in
length, as compared to the buccal flange, as it
approaches and enters the retromylohyoid area.
 Border molding the custom tray

 Border molding is shaping of the border areas of an

impression material by functional or manual manipulation
of the soft tissue adjacent to the borders to duplicate the
contour and size of the vestibule. (– gp)
 Borders of the tray are molded to a form that will be in
harmony with the physiological action of the limiting
anatomical structures.
 Most commonly used border molding materials are:-
1) Modelling compound sticks.
2) Autopolymerizing acrylic resin
3) Elastomeric materials
4) Impression waxes.
Modelling compound sticks:
Advantages:
 Soften easily.

 Quite hard at mouth or room temperature so other areas

of periphery can be molded with least possible distortion
to the previously completed section.
 Corrections easily accomplished.

Autopolymerizing acrylic resins:

Disadvantages:
 Irritating.

 Strong odor.

 Heat produced polymerization.

Elastomeric materials:
Heavy body-border molding.
Advantage-
 wide range of working and setting time.

 Elastic recovery good.

Disadvantage:
 Borders difficult to trim.
Suggested sequence for border molding the
maxillary arch
Suggested sequence for border molding the
mandibular arch
Only sufficient border molding material is While the material is still softened,
added to the impression tray to slightly the border molding movements are
overfill the space created when the tray completed.
was shortened 2 mm from the depth of the
vestibule.
 Border molding the maxillary arch
LANDMARK MOVEMENTS
1. Labial frenum Elevation of lip upward

2. Labial vestibule Elevating the upper lip outward downward

inwards

3. Buccal frenum Elevating the cheek outward inward downward

and backward forwards

4. Distobuccal region Elevating the cheek outward downward and also

opening the mandible wide, and moving the
mandible side to side

5. Posterior palatal seal By asking the patient to say ah in unexaggerated

area manner with his head bent downward
 Border molding the mandibular arch
LANDMARKS MOVEMENTS
1. Labial frenum Recorded by elevation of lower lip

2. Labial flange Recorded by elevating the upper lip and extended it

outward, upward and inwards.

3. Buccal frenum Recorded by elevating the cheek outward and

upward, inwards, backwards and forwards.

4. Distobuccal Recorded by extending the cheek outward inwards

region upwards.

5. Lingual flange Recorded by moving the tongue from side to side.

6. Lingual frenum. Protrude his tongue outward to touch his lip.

7. Massetric notch Asking the patient to close against force or bite.

The border molding is completed, and all excess
material has been removed.
 SECOND TECHNIQUE
ONE- STEP BORDER- MOLDED TRAY

 Has two general advantages:

 The number of insertions of the tray for maxillary and

mandibular border molding is reduced.

 Developing all borders simultaneously avoids

propagation of errors caused by a mistake in one
section affecting the border contours in another.
 The requirements of the material used

 Have sufficient body

 Allow some pre shaping
 setting time of 3 to 5 min
 Retain adequate flow
 Not cause excessive displacement of the tissues
 Be readily trimmed & shaped
 Thefollowing procedure utilizes polyether
impression materials for border molding.

1. Place adhesive for polyether impressions on the

borders of tray.

2. Express a 3- inch strip of polyether material from

large tube onto a mixing pad. Next express 2.5 inches
of catalyst to provide sufficient working time to
complete border molding.

3. Thoroughly mix material for 30 to 45 seconds using a

metal spatula.
4. Position the polyether material on the borders, making
certain that a minimum width of 6 mm exists on inner
portion.

5. Quickly preshape the material to proper contours with

fingers moistened in cold water

6. Place the impression tray in the mouth .

7. Inspect all borders to be sure that impression material is

present in the vestibule

8. Border molding is done

9. Remove tray when impression material is set.

10. Examine border molding to determine that it is adequate.

 Making final impression
 The final impression is made using the desired impression
material.

 The patient is asked to rinse with cold water or

mouthwash to remove away the saliva.

 The selected impression material is mixed according to

the manufacturer’s directions and applied evenly to the
tray.

 When inserting the impression tray, the clinician must

carefully observe the seating of the tray onto the tissues.
 Border molding of the impression must be initiated
before the impression material begins to polymerize
and must continue until the material begins to
polymerize.

 Care is often required to minimize patient discomfort

when removing an impression.

 The impressions should be rinsed and then

disinfected before further handling.
 POSTERIOR PALATAL SEAL AREA
“The soft tissue at or along the junction of the soft and hard
palate on which the pressure with in the physiological limits of
the tissue can be applied by a denture to aid in the retention of
the denture.” -GPT.

Made of two regions:

 Pterygomaxillary seal
 Posterior palatal seal
Methods of recording

 Arbitrary scrapping.
 Fluid wax technique or functional
technique
 Conventional technique
 Arbitrary scrapping.
 Fluid wax technique or functional
technique

 Mouth temperature wax is

painted on the impression
surface with in the outline of
the post dam area.
 The impression is inserted in
the mouth and held under
pressure.
 The patient is asked to firmly
place his tongue against the
lower incisor area and rotate
his head periodically.
 The wax should exhibits a
butterfly appearance.
 Conventional technique
”scrapping the cast according to functional tracing of the
post dam area”
 The patient should be seated in an upright position.
 Tray selection : the tray should be of correct size because
large tray takes more impression material .
 Border molding : Post dam must be done to prevent
impression material to escape posteriorly and initiate gag
reflex .
 Use as little material as possible for making the impression .

 Thick mix of the impression material and away from the

patient.
 The tray inserted first posteriorly then anteriorly.
 The patient should blow the nose to clear any nasal
obstruction and then encouraged in deep nasal breathing .

 Explain to the patient that, as soon as the impression is seated

the head may be brought well forward and that a bowl will be
provided to hold under the chin to catch any saliva that may
run out of the mouth.

 Desensitize the surface of the mucous membrane with :

 phenol mouth washes.
 Application of topical anesthesia (cream or spray)
 CONCLUSION

“Ideal impression must be in the mind

of the dentist before it is in his hand.
He must literally make the impression
rather than take it”
M.M. Devan
 REFERENCES
 Zarb G, Hobkirk JA, Eckert SE, Jacob RF, editors. Prosthodontic
treatment for edentulous patients. 13th ed.

 Arthur O. Rahn, John R. Ivanhoe, Kevin D. Plummer Prosthetic

Treatment of the Edentulous Patient _ Fifth Edition,.

 Sheldon Winkler, Essentials of complete Denture prosthodontics, 2nd

edition,2012.

 Sharry .J.J, Complete denture Prosthodontics, 3rd edition,

 R.M. Basker, Prosthetic Treatment of the Edentulous Patient Fifth Edition