Impression techniques in complete dentures.ppt

DR TESSA KURIACHAN
READER
DEPARTMENT OF PROSTHODONTICS
SREE ANJANEYA INSTITUTE OF DENTAL SCIENCES

LANDMARKS IN MAXILLA
• LIMITING STRUCTURES
– Labial vestibule
– Labial frenum
– Buccal frenum and vestibule
– Hamular notch
– Posterior palatal seal area
• Relief areas
– Incisive papilla
– Midpalatine raphae
– Fovea palatine
• Supporting structures
• Primary stress bearing
– Hard palate
– Postero lateral slopes of
residual alveolar ridge
• Secondary stress bearing
– Rugae
– Maxillary tuberosity

IN MANDIBLE
• LIMITING STRUCTURES
– Labial frenum and vestibule
– Buccal frenum and vestibule
– Lingual frenum alveololingual
sulcus
– Retromolar pads
– Pterygomandibular raphae
• SUPPORTING STRUCTURES
– Buccal shelf area
– Residual alveolar ridge
• RELIEF AREAS
– Crest of alveolar ridge
– Mental foramen
– Genial tubercle
– Torus mandibularis

IMPRESSION:
 An impression is defined as a negative likeness or copy in reverse
of the surface of an object : an imprint of the teeth and adjacent
structures for use in dentistry.GPT-8
 An impression is defined as an imprint or negative likeness of the
teeth, of the edentulous areas where the teeth have been removed,
or of both, made in a plastic material that becomes relatively hard
or set while in contact with these tissues.- Winkler.

 An impression is record of negative form of tissue of oral cavity
that make up the basal seat of denture- Boucher.
 A complete denture impression is a negative registration of entire
denture bearing , stabilizing and border seal areas present in an
edentulous mouth.- Levin. Heartwell and Rahn

According to Zarb. Bolender….12th Edition
 Healthy oral tissues.
 Impression should include all the basal seat area with in the limits
of health and function of the supporting and limiting tissues.
 The borders must be in harmony with the anatomical and
physiological limitations of oral structures.
 Physiological type of border moulding should be performed.
 Proper space should be provided with in the impression tray for
the selected impression material.

 Impression must be removed from the mouth without damaging
the mucous membrane of the residual ridges.
 A guiding mechanism should be provided for correct positioning
of the tray.
 Tray and impression material should be made of dimensionally
stable material.
 External surface of the impression should be similar to the
completed denture surface.

1. Preservation of the alveolar ridges
2. Retention
3. Stability
4. Support
5. Esthetics

 “ It is the perpetual preservation of what already
exists and not the meticulous replacement of what
is missing.”
 Wide tissue coverage
 Avoiding Excessive Pressure

 Definition
That quality inherent in the dental prosthesis acting to resist the
forces of dislodgment in a direction opposite to that of its insertion.
 Factors Affecting Retention
1. Anatomical Factors :
Size and Quality of denture bearing area.

2. Physical Factors:
• Adhesion
• Cohesion
• Interfacial Surface Tension
• Capillary Action
• Atmospheric Pressure
 Thin Mucous Saliva And a Good Peripheral Seal

Impression techniques in complete dentures.ppt

3. Mechanical factors:
• Undercuts
• Retentive springs
• Denture adhesives
• Suction chamber and suction discs
1.Muscular factors :
Correctly shaped Polished Surfaces
Correct position of teeth

 Definition
The Resistance to vertical forces applied in a direction
towards the basal seat.
 Areas Of Support : Acc to Bernard Levin
1. Primary: Right Angle to the Occlusal Forces and do not
resorb easily.
2. Secondary: Greater than at Right Angle or are parallel
to them…also tend to resorb under load.
3. Slight : Vestibular areas.

 Defintion:
The ability of the denture to remain securely in place when it
is subjected to horizontal forces.
 Requirements for Stability
1. Retention
2. Occlusion
3. Proper tooth arrangement
4. Occlusal Plane
5. Muscle control and coordination

 Labial and Buccal borders must support the lips and cheeks.
 Impressions should be completed with the same peripheral
width as that of the finished denture.

1. Based on Theories:
1. Definite Pressure/Muco-compressive Technique
2. Minimal Pressure/Muco-Static Technique
3. Selective Pressure Technique
2. Based on Mouth Positioning :
1. Open Mouth Technique
2. Closed Mouth Technique

1. Based on Manipulation:
1. Hand Manipulation
2. Functional Movements

BASED ON THEORIES OF IMPRESSION
BASED ON THEORIES OF IMPRESSION
MAKING
MAKING
Definite Pressure Technique - proposed by Green
 Main objective - attain better retention of the denture.
 Advocates believe that the peripheries of the dentures must
be established during function.
 Not much regard to the biological aspect.
 Advocates of this technique often employed closed mouth
procedures.
 A positive peripheral seal is obtained by this procedure.

 TECHNIQUE- Described by Liberthal.
 Disadvantages
• Tissue Rebound.
• Force applied to the centre of the palate
• Retention-Friend or Foe?
• Tissue Ischaemia
• Inadequate border molding due to closed mouth method.
• Over-extended dentures.

 Main Objective: Preservation of ridges with acccurate
reproduction in static stage.
 Based on Pascal’s Law.
 Impression material should record without distortion, every
detail of the mucosa.
 Impressions should cover only the area of oral cavity where the
mucous membrane is firmly attached to the underlying bony
structure.
 The depth detail and outline of the flange has no retentive
value.

 Technique
 Disadvantages
1. Mucosal topography is not static.
2. Inadequate retention,support and stability due to
short flange.
3. More stress concentration,thus harmful to tissues.
4. Claims of great accuracy faulty as saliva is always
present between the material and tissue.
5. Pascal’s Law can only be partially applied to oral
tissues as they are compressible.

 MUCO-SEAL TECHNIQUE – Technique stated by Pryor.
-Variation of Mucostatic technique.
-Posterior lingual border covers the retromolar pad and then
drops as it comes anteriorly.
-The anterior lingual border is molded by the ‘ floor of the
mouth with the tongue in repose.
The tray is extended horizontally backward, over the sublingual
glands towards the tongue to affect a border seal.

 Combines the principles of both pressure and minimal
pressure techniques.
 Main Objective- Tissue preservation is combined with the
mechanical factor of achieving retention.
 Certain areas of the maxilla and mandible are by nature
better adapted for withstanding extra loads from the
forces of mastication.
 Primary Stress Bearing Areas
 Secondary Stress Bearing Areas
 Relief Areas

 Advocated maximum extension with in the comfort and functional
limits of the surrounding muscles and tissues.
 Disadvantages
 Cannot be used in flabby ridge cases
 Technique demands firm ,healthy mucosa covering the ridge
 Opponents of this technique feel that it is impossible to
record some areas with different pressure from that applied
to other areas.

 Closed Mouth Technique : Supporting tissues are
recorded in functional relationship.
 RATIONALE: Natural movements by the patient will conform the
impression material to the anatomic limitations when the
mouth is closed and under pressure.
 TECHNIQUE:
 Advantages :
 Interferences of tray handles and operator’s finger is
eliminated.

 Disadvantages:
 Rebound of the tissues during rest leads to denture
displacement.
 Tendency for over-extension or under-extension
 Contraindicated in the presence of considerable amount
of movable tissues.
 A constant pressure is exerted over tissues, hence blood
supply is compromised leading to ridge resorption.

 Open Mouth Technique : Patient’s mouth is open when
the borders are molded.
 Rationale: Bitting force does not cause dislodgement but
functional movement does.
 This technique is preferred over closed-mouth technique
 Visualization of the muscle trimming
 Various movements can be accomplished easily.
 Denture retention can be predicted in open as well as in
closed mouth movements.
 Pressure or pressure-less technique can be employed by using
this technique.

 Hand manipulation :
The contour of the denture borders may be obtained by
the dentist with the use of manual manipulation of the lips and
checks within functional limits. Patient’s tongue movements
record the lingual borders.
 Functional movements :
The denture border may also be formed by having the
patient make “functional” or “physiological” movements such
as sucking, grinning, licking, swallowing etc.

 Examination and conditioning of the patient and mouth.
 Selection of impression material (Material)
 Selection of impression trays (Mold)
 Selection of impression technique (Method)
 Seating of the patient
 Making the preliminary impression
 Border-moulding procedures
 Making the final impression

 A complete case history and clinical examination.
 Patient’s education and instructions.
 Patients with old denture are instructed to discontinue old
denture at least 72 hours prior to impression.
 Tissue conditioners may also be employed to bring the
tissues back to health.
 Drugs may also be given to reduce excessive salivation.

 The material is selected according to the clinical findings,
availability, which in turn influences the technique as well.

 Depending on the mode of hardening or setting
• Thermoplastic impression material
• Thermo set impression material
 Based on the physical properties or flexibility when set or at the
time of removal from the mouth.
• Rigid or non-elastic
• Elastic
 Based on the tissue displacement during impression making
• Mucocompressive
• Mucostatic
 Based on the prosthetic use
• Preliminary impression material
• Secondary or final impression material

 A receptacle in to which suitable impression material is placed to make a
negative likeness. (GPT)
 CLASSIFICATION OF IMPRESSION TRAYS
 Based on whether they are prefabricated or individualized
 Stock trays
 Custom trays / special trays
 Depending on the presence of perforations
 Depending on the clinical use
 Depending on the material made up of
 Metallic trays
 Non-metallic trays

Plastic Trays with Attachable Metal Handles
Metal Stock Trays

40
4. Tray should be adjusted by
bending .
1.Selection of stock tray. 2. Position borders at hamular notches.
3. Lift the tray anteriorly, 3-5 mm
space for impression material.

5. Border of the tray should
be cut if required
6. Borders should be
smoothened
7. Material
Manipulation

8. Placing the tray in the patients mouth.
9. Performing Movements to mold the material.

10. Stabilizing the tray until the material hardens.
11. Removal of impression and
cooling in chiled water.

Mandibular impression
 The distolingual flange areas can be molded
with fingers to simulate the final impression.
 The left posterior corner of the tray is
inserted while retracting the right cheek
with operator’s left hand and tray is rotated
and centralized over the ridge.

 Patient is instructed to lift the tongue, and tray is seated while
applying pressure
 Light border molding movements are performed including tongue
movements.
 Compound is allowed to harden and chilled after removal
impression is inspected.

Storage and handling of impressions
 Impression should not be kept surface touching the alginate to
prevent distortion due to tray weight.
 Any unsupported excess material should be cutoff.
 Alginate should not be stored for too long and should be poured as
early as possible.
 Compound impression should also be poured immediately for
greater accuracy, however can be stored longer than alginate.

 2% glutaraldehyde
 10% sodium hypochlorite
 Iodophors
 Household bleach (1:10)
 Other synthetic phenols derivatives.

 Cast should be soaked in slurry water
 Sulcus depth, tray borders and spacer and relief areas should
be marked on the cast.
 Severe undercuts should be blocked out using wax.

Relief Areas
 What? It is the reduction or elimination of the undesirable
pressure or force from a specific region under a denture base.
 Where? Incisive papilla, mid palatal raphae in maxilla and
ridge crest in the mandible should be relieved.
 Why? Helps to record the relief tissue in anatomical rest
position.

 Additional relief may be required for clinical situations like
flabby ridges, sharp bony projections.
 Thickness of the relief will vary according to the quality of the
tissue.
 Depends on the compressibility of the tissues requiring relief.

Wax Spacer
 What? Wax spacer is given for the creation of space in an
impression tray for the impression material.
 Where? Considerable debate surrounding the extent of spacer
wax with different authors suggesting different designs.
 Thickness varies with the type of impression material used:
Zinc Oxide Eugenol-
Elastomers-

Roy Mac Gregor Neill
Sharry
Boucher
Rudd and Morrow
Bernard Levin
SPACER DESIGNS

Tissue Stops
 What? The part of the special tray that extends in to the cut
out of the spacer is called as stopper.
 Why? proper orientation and stabilization of the tray while
making impression.
 Where?

 It is an individualized tray made for a particular patient .
It is fabricated on a preliminary cast made from a
preliminary impression and is used for making the final
impression.
 Materials used for fabrication of special tray include:
1.Shellac
2.Cold cure acrylic resin
3.Vacuum formed vinyl or polystyrene
4.Vacuum formed thermoplastic resins
5.Light cure resins(triad VLC, Dentsply)
6. Type ll impression compound

 Different techniques to fabricate special trays
1. Modified stock trays method with type ll impression compound
2. Double thickness or reinforced shellac base plate
3. Sprinkle-on method for acrylic resin trays
4. Finger adaptation Dough method for acrylic resin trays
5. Vacuum-formed thermoplastic resin trays
6. Visible light cure resin trays

Tray handle
 Maxillary Tray: 1 Handle on the incisor region at an angle of
45°.
 Mandibular Tray:1 Handle on the Incisor Region at an angle
of 90° and 1 Handle each on the first molar region.
 They should not interfere with the border molding
maneuvers and lip movements.
 DIMENSIONS: Length 8-10 mm
Width 8-10 mm
Thickness 3-4 mm

Depth of the sulcus is marked on the cast Borders are kept 2mm short
Borders should be beveled. Vibrating line marked.

Tray Inserted In the patient’s mouth
Lip and cheek are
reflected and the
borders are observed
Over-extensions are
trimmed

Depth of the sulcus is marked on the cast Borders are kept 2mm short
Lip and cheek are reflected and the borders
are observed
Over-extensions are trimmed

Tongue is Protruded Lateral movements performed
Over-extensions are trimmed

 A/k Peripheral tracing , Muscle trimming
 Determining the extension of a prosthesis by using tissue function
or manual manipulation of the tissues to shape the border areas of
an impression material. .(GPT-8)
 Border molding materials include:
Modeling compound sticks(Green Stick)
Polyether impression paste (Knap)
Tissue conditioners
Auto polymerizing acrylic resin
Impression waxes
Periopak ( Kirk and Holt )

Methods of border molding
 Functional method
Normal functional movements mold the borders
in harmony with muscles action
 Smiling, whistling and grinning (labial and buccal
borders)
 Sucking (buccal frenum and buccal borders)
 Licking the lips and tongue movements (lingual borders)
 Swallowing (lingual border and floor of mouth)
 Opening, closing and side to side movements
(distobuccal borders )

 Digital manipulation
 The dentist manipulates the lips and cheeks of the
patient to simulate the influence of these on the denture
borders.
 It is easy to perform and does not require much of
patient cooperation.
 Digital manipulation is influenced by the direction of
movement and the force applied.
 Combined
 Border molding is usually done by a combination of
digital manipulation by the dentist and functional
movements by the patients.

Softened compound added from hamular
notch to buccal space
Cheek gently massaged.
Softened again with alcohol torch.
Tempered in warm water bath.

Labial Border Molding Molding the Frenum
Compound placed on posterior border. Tray seated in mouth with firm pressure.

66
Compound placed on posterior border
Compound added on buccal border
The tray gently seated in place.
The border should be smooth,round
and convex.

67
Compound placed on labial
border
Labial Border Molding
Lingual Border Molding Movements

One step border molding procedure (polyether)
( Boucher, JPD:1979:41:347 )
Dale E. Smith
1. An adhesive is applied on the borders of the tray.
2. The polyether material is mixed and introduced in to a
plastic impression syringe with slightly less catalyst.
3. Polyether material is syringed around the borders and
across the posterior palatal seal areas.
4. Material is quickly preshaped to proper contours with
finger moistened in cold water.
5. Tray is inserted in the mouth making certain that lip and
cheeks are retracted sufficient to avoid distortion of
material from tray borders.

6. Borders should be checked in the mouth for proper
extensions.
7. All border molding movements are carried out quickly.
8. When the material is set tray is removed from mouth.
9. Border molding is examined for accuracy.
10. Any deficient site can be corrected with a small mix of
polyether material added to the appropriate area.
 Advantages
-Numbers of insertion of the tray are reduced.
-Developing all borders simultaneously avoids
propagation of errors caused by a mistake in one
section affecting the border contours in another.

Preparing the tray for final impression
 Removing the wax spacer
 Removing the wax relief
 Escape holes:
 To reduce the buildup of hydrostatic pressure
 Facilitates escape of excess material
 Placed with no.6 round bur one half inch apart
 Drying the mouth

Making the final impression
 Zinc oxide eugenol base and catalyst is dispensed in two
equal lengths and mixed to a smooth uniform mix with out
entrapping air bubbles.

Common faults in impression making
 Insufficient depth in the facial and lingual sulci
 Short tray extensions
 Lack of impression material
 Insufficient pressure
 Not seating the tray completely
 Tissue trapped like tongue and cheeks
 Insufficient flow of material

 Edge of the exposed through the impression
 Improper positioning and centralize the tray
 Use of too large or too small tray
 Excess material extending beyond borders
 Excessive or prolonged pressure
 Excess loaded material

 Asymmetrical impression
 More material on one side of the tray
 Failure to center the tray
 Lack of tissue manipulation
 Deficiency in the mid line of the palatal vault
 Insufficient material in palatal area
 Insufficient pressure
 Impaired flow of material
 Trapped air

 Impression separation from the tray
Tray retention can be improved by
 More no. of perforations
 Forcing the material through the holes while loading
 Having a rim lock
 Use of suitable adhesive
 Careful retrieval of the impression from mouth

Impression techniques in compromised situations
&
Complicating factors
Unsupported hyperplastic flabby ridges.
 Severely resorbed mandibular ridge.
 Hyperactive gag reflex.
 Restricted access to oral cavity.
 Excessive salivation.
 Unemployed Mandibular Ridge.

Impression technique for patient with unsupported flabby ridges
The hypermobile tissues should be recorded without distortion
with minimum displacement and rest of the tissues are recorded
with selective pressure technique.
 A primary impression is made with alginate and a special tray is
constructed with relief wax placed over the mobile tissues, border
molding is carried out and the final impression is made with free
flowing material.

 Techniques :
Hobirk Technique
Walter Technique
Filler Technique
Zafrulla Khan Technique
Splint method by Allan Mack

 Hobkirk technique:
The impression is made with heavy bodied silicone in a
border molded special tray. The heavy bodied material
overlying the hypermobile tissue is cut away and escape
holes are made. A wash impression is then made with light
bodied material.
 Walter Technique:(BDJ 1964:117:392)
Recorded the healthy denture bearing tissue with zinc
oxide eugenol paste and the undisplaced fibrous tissue
with impression plaster.

 William H.Filler (JPD 1971:25:609)
 Has described a modified impression technique used in
patient with extremely hyperplastic residual ridges and
surgical preparation of the mouth is contraindicated.
 It makes use of two trays where the second tray is keyed
over the first tray in its proper location.

J. prosth.dent ,june 609-612 1971
Light bodied Permlastic is used in the
first tray and plastogum is painted on
the second tray and tray is seated in
position.

Management of the flabby ridge: using contemporary materials
to solve an old problem ( BDJ:2006:200:258 )
Lynch CD and Allen PF
Primary impression with alginate
Perforations on the displaceable area on
the custom tray
Heavy body silicone material impression
made on the normal tissues
light bodied silicone material of
displaceable area

 Useful in tissues that are exceptionally flabby.
 A loosely fitting tray or a special tray made with heavy relief
over the flabby areas is taken, plaster is mixed and applied over
the flabby area to a thickness of about 3mm and is allowed to
set.
 Tray is filled with 2nd mix of plaster and the impression is
made.
 The initial coating of the flabby areas thus acting as a ‘splint’
whilst the impression is made and is removed along with the
impression.

Impression Technique For Severely Resorbed Mandibular
Ridge
 PROBLEM: Lack of ideal amount of supporting structure,and
 Support and the encroachment of the surrounding mobile tissues
on to the denture border reduce both stability and retention.
 If the alternative methods like implants, bone grafting,
vestibuloplasty are not indicated ,one has to resort to conventional
means.
 Thus the main aim of the impression procedure is to gain
maximum area of coverage with minimum pressure by obtaining a
fairly long retromylohyoid flange for a better border seal and
retention.

 Techniques :
Flange Technique
Dynamic Impression Technique
Winkler’s Technique(Functional Reline)
Miller’s Technique
Roberto Von Krammeck Technique
Robert L Defranco (Functional Reline)
Mccold and Tyson Admixed Technique

 Flange technique (JPD 1966:16:394-413)
 Frank Lott and Bernard Levin
 Involves making impressions of the soft structures
adjacent to the buccal,lingual, labial surfaces and
incorporating the resulting extensions or flanges in
denture.
 Fluid wax is rolled from the retromolar pad region to
sublingual region ,large enough to restore the areas of
estimated resorption.
 Patient is asked to forcefully perform functional
movements to give a border extensions which covers
maximum surface area.

Dynamic impression methods.
(G. Tryde, K.Olsson, Jenson)
Advantage :
- Avoidance of the dislocating effect of the muscles on
improperly formed denture borders .
- complete utilization of the possibilities of active and passive
tissue fixation of the denture.
Impression material : Irreversible hydrocolloid
Impression tray serves 3 functions
1. Must not interfere active muscle movements -
2. Permit proper thickness of impression material
3. Stabilize the mandible in correct position -

 Characteristics of Dynamic Dentures
1.Longer Borders Buccally and Lingually
2. Marked Sub-Lingual Extension shaped like a shelf.
3. Labially the border is determined by mentalis and
orbicularis oris.
4. Buccal border-Buccinator muscle.

 Over extended primary impression of alginate was made.
 Occlusal wax rims were constructed and the borders were adjusted so
that the lingual flange and sublingual crescent area were in harmony
with the resting and active phases of the floor of the mouth.
 Closed mouth technique - 3 applications of conditioning material were
used – each application for approximately 8-10 minutes.
 The third and final wash was made with light bodied material. The
technique resulted in an impression that had tissue placing effect with
relatively thick buccal lingual and sublingual crescent area.

 Miller’s Modification:
uses mouth temperature waxes instead of tissue
conditioners.
 Roberto Von Krammeck Modification:
Used Modelling Compound.

 Robert L Defranco Technique
Open and Closed Mouth Procedure
-Jaw relations at selected VD
-Develop mandibular buccal borders with tissue conditioners
-Lingual borders developed with mouth open
-Patient is instructed to make ooo and eee sounds while biting on
the occlusal rims.
-Final Impression is made with Light Body with Mouth Open

 McCold and Tyson Admixed Technique
-Uses Admix of Impression Compound and Green Stick in
the ratio 3:7
-Rationale: Admix removes any soft tissue folds and
smoothens them over the bone

Neutral zone technique.
 The neutral zone is the area where the displacing forces of the lips
cheeks and tongue are in balance. It is in this zone that the natural
dentition lie, and this is where the artificial teeth should be
positioned.
 This area of minimal conflict may be located by using the neutral
zone technique. The artificial teeth can then be set up in the correct
positions. This technique is described below.
Acrylic tray with spurs for
retention
Occlusal pillars to the correct
height

Establishing correct
vertical height
Viscogel rim being
molded within the mouth
Completed viscogel imp.

Patients problems should be identified before impression is made
 Prosthodontic management
- Avoid thick or over extended trays.
- Avoid excess loading of material
- Use a fast setting material
- Singer’s marble technique can be followed
 Distraction maneuvers
- Engage the patient in conversation of some special
interest.
- Ask the patient to concentrate on one foot or to raise it.
 Pharmacologic measures
- Local anaesthetics
- Antihistamines, Sedatives, CNS depressants
 Psychological intervention
- Hypnosis helpful in certain cases
.

A MODIFIED EDENTULOUS MAXILLARY CUSTOM
A MODIFIED EDENTULOUS MAXILLARY CUSTOM
TRAY TO HELP PREVENT GAGGING
TRAY TO HELP PREVENT GAGGING
Gordon m callison
J.prosth.dent1989:62

Impressions In Patients With Restricted Access To Oral Cavity
 Walter described a technique with the use of sectional
stock trays.
 Impressions of each side of the jaw were made one at a
time and the two halves were assembled together before
pouring the cast.

JPD 2004, vol92 page322-7
 This clinical report describes the fabrication of a collapsible
maxillary removable complete overdenture using a sectional
impression tray technique and a custom-made palatal hinge
mechanism.
 Patient-edentulous woman with microstomia resulting from
scleroderma

Excessive salivation
 Placing cotton rolls in the upper buccal sulcus and in the
floor of the mouth.
 Rinse the mouth well with an astringent mouth wash just
prior to impression.
 Use of saliva ejector.
 Rinse with cold water.
 Antisialogue in extreme cases.

Unemployed mandibular ridge
 Due to continuous ridge resorption in old denture wearers
support of the denture becomes progressively transferred
to peripheral parts of the denture bearing areas while the
ridge takes less load. Thus the ridge is referred as
unemployed.
 TECHNIQUE:
Old denture New denture

 Primary impression with alginate and cast poured.
 An impression compound impression is taken of the cast with this
tray and chilled.
 Periphery is trimmed.
 Green Stick Is Applied to the periphery and placed in patients mouth
to record borders with border molding.
 The compound over the ridge is then cut with a sharp knife.
 Record the working surface with impression paste under heavy digital
pressure to transfer as much of the load as possible to the peripheral
parts of the denture bearing area.

 The main objective of impression making is to construct
dentures having maximum retention and stability without
causing any damage to the supporting structures.
 A good impression often favorably impresses and relieves
the anxieties of the patient.

 Thus the choice of impression technique and material is
made by the dentist on the basis of the oral
conditions ,concepts of function of the tissues surrounding
the denture and ability to handle the available impression
material.
 A good impression must aid to fulfill M.M Devan’s dictum
“It is perpetual preservation of what already exist and not
the meticulous replacement of what is missing.”

 Zarb GA,Bolender CL,Prosthodontic treatment for edentulous
patients,12th
ed.
 Boucher CO,Swenson’s complete dentures,6th
ed.
 Zarb GA,Bolender CL,Boucher’s Prosthodontic treatment for
edentulous patients,11th
ed.
 Winkler S,Essentials of Complete Denture Prosthodontics.
 Anusavice KJ, Phillips’ science of dental materials,10th
ed.
 Rudd KD, Morrow RM, Dental laboratory procedures
complete dentures Vol. l ,2nd
ed.
 Hobkirk JA,Dental techniques, A colour atlas of complete
dentures

 Physiological determinants of primary impressions for complete
dentures,JPD:1984:53:611.
 Final impressions for complete dentures,1970:23:250.
 Predictable impression procedures for complete dentures
DCNA:1996:40:39.
 The maxillary denture: its palatal relief and posterior palatal seal
JADA:1967:75:1182.
 Impression procedure for severely atrophic
mandible,JADA:1972:84:130.
 Tongue position in relation to the edentulous mandibular
impressionsJPD:1987:57:458.
 A selective pressure technique for the edentulous
maxilla,JPD:2004:92:299.

“ If you can meet with triumph and disaster ,
And treat those two imposters just the same”
Roger Federer
Champion ,
Wimbledon 2009

Impression techniques in complete dentures.ppt

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