theories of impression making in complete denture

THEORIES OF IMPRESSION MAKING

AND IMPRESSION PROCEDURE FOR COMPLETE

DENTURE

Dr. Dipal Mawani1

CONTENTSHistory

Definitions

Biologic Considerations For Maxillary Impressions

Biologic Considerations of Mandibular Impressions

Principles of Impression Making

Classification of Impressions

Impression Procedures

Impression Techniques in Compromised Situations

Review of literature

Conclusion

References2

3

“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. De Van

History

1728: Pierre Fauchard made dentures by measuring the mouth with compasses and cutting bone into an approximate shape.

1845-1899: Concepts of atmospheric pressure, maximum extension ofdenture bearing area, equal distribution of pressure and close adaptation ofthe denture bearing tissues were stressed.

1886 – Richardson mentioned about making plaster impressions of tissuesat rest & achieving adhesion by contact

1896: Greene brothers introduced Muco-compressive theory.

1900-1929: Concepts like Rebase impressions, border molding, posterior palatal seal and techniques for flabby tissues were introduced.

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1930-1940: This era recognized the anatomy of the denture bearing areas and muscle physiology was related to impression procedures. This is evident by descriptions of border molding & concept of special trays.

1946: Page gave the concept of mucostatics

1951: Boucher introduced selective pressure theory.

1965-1980: Techniques to manage compromised situations were introduced

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COMPLETE DENTURE IMPRESSION :-

a complete denture impression is a negative

registration of the entire denture bearing,

stabilizing and border seal areas present in the

edentulous mouth. (GPT-9)

PRELIMINARY IMPRESSION :-

a negative likeness made for the purpose of diagnosis, treatment planning, and/or the

fabrication of a custom impression tray preload . (GPT-9)

BORDER MOLDING :-the shaping of impression material along the border areas of an

impression tray by functional or manual manipulation of the soft tissue

adjacent to the borders to duplicate the contour and size of the

vestibule (GPT-9)

IMPRESSION MATERIAL :-

any substance or combination of substances used for making an

impression or negative reproduction (GPT 9)

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Limiting and supporting structures of maxillary denture bearing area

8

Maxillary stress bearing and relief areas

Primary

Hard palate on either side of

raphae

Firm tuberosity

9

Secondary

Rugae area

Crest of Residual Alveolar Ridge

Relief

Incisive Foramen

Mid Palatine Raphae

Palatal Tori

Sharp Spiny Processes

Limiting and Supporting areas of mandibular denture bearing area

10

Mandibular Stress bearing and Relief areas

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Primary

Buccal Shelf Area

Retromolar Pad

Secondary slopes of

Residual Alveolar Ridge

Relief

Mandibular Tori

Mental Foramen

Genial Tubercles

Prominent Retromylohyoid Ridge

To achieve a successful impression, the following concepts should be adhered to, irrespective of the selected technique:

1. The impression should extend to include the entire basal seat.

2. The border must be in harmony with the anatomical and physiological limitations of the structures.

3. Physiological type of border moulding procedure performed (dentist /patient under the guidance of the dentist).

4. Space for the final impression material within the impression tray.

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5. Selective pressure on the basal seat during impression making.

6. The impression must be removed without damage to mucous membrane

7. A guiding mechanism is provided for correct positioning of the tray.

8. Tray and impression material should be dimensionally stable.

9. External shape is similar to external form of the complete denture.

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Principles of

Impression Making

Support

Retention

StabilityEsthetics

Preservation of alveolar

ridges

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Retention

• that quality inherent in the dental prosthesis acting to resist the forces of

dislodgment along the path of placement (GPT-9)

• It is the quality inherent in the prosthesis which resists forces of gravity,

adhesiveness of food and forces associated with opening of mouth

15

Physical Factors

affecting Retention

Adhesion

Cohesion

Gravity

Interfacial Surface Tension

Capillary Attraction

Atmospheric Pressure & Peripheral

Seal

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Adhesion :-

• Physical attraction of unlike molecules

• It acts when saliva sticks to the denture base & to the mucous membrane of basal seat .

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Cohesion:-

the act or state of sticking together tightly (GPT-9)

• Physical attraction of like molecules for each other

• Occurs within the layer of fluid (usually saliva ) present between the denture base & the mucosa.

• Effective – layer should be thin

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Interfacial surface tension:-

• Resistance to separation by the film of liquid between the denture

base & the supporting tissues .

• Dependent on the ability of the fluid to wet the rigid

surrounding material .

19

Mucostatics dismiss adhesion and cohesion as factors in retention,

the entire phenomenon being attributed to interfacial surface

tension.

But it has been proved that if it was not for the forces of adhesion

and cohesion, the forces of interfacial surface tension wont exist.

Attachment of a denture is possible because both tissue and denture

base material can become wet which means its molecule will adhere

to water molecules.

Basic principles in impression making

J Prosthet Dent 2005;93:503-8.20

Atmospheric pressure:-

• Acts to resist dislodging forces applied to the denture, if dentures have an effective seal

around their borders i.e. Peripheral Seal. (14.7lb/in2)

• Retention due to atmospheric pressure is directly proportional to the area covered by

the denture base.

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Anatomical Factors involved in Retention

• Maxilla – PPS, Retro zygomatic space

• Mandible – Pear shaped pad, Retro Mylohyoid Space

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Mechanical Factors involved in Retention

• Undercuts

• Rubber Suction Discs

• Magnets

• Suction Chambers

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Stability

the quality of a complete or removable partial denture to be firm,

steady, or constant, to resist displacement by functional horizontal

or rotational stresses (GPT-9)

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Support

the foundation area on which a dental prosthesis rests;

“the resistance to forces directed toward the basal tissue or underlying

structures” (GPT-9)

Esthetics

Role of esthetics in impression making refers to the development of the

labial and buccal borders, so that they are not only retentive but also

support the lips properly.

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Preservation of the alveolar ridges

DeVan (1952) stated that “the preservation of that which remains is of utmost importance and not the meticulous replacement of that which has been lost”

• Stress-bearing areas and non-stress bearing areas should be recorded under stress and relief respectively.

• Peripheral tissues to be recorded without over extensions.

• Wide tissue coverage

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Classification

Depending on the theories of

impression making

Muco-compressive

Muco-static

Selective pressure

Depending on the technique

Open Mouth

Closed Mouth

Depending on the purpose

of the impression

Diagnostic

Primary

Secondary27

Definite pressure technique/ Muco-compressive

• Introduced by Greene brothers

• The tissues recorded under functional pressure provide better support and

retention for the denture.

• Many advocate the use of closed-mouth impression techniques.

• Advocates of this theory believe that occlusal loading during impression

making is comparable to the occlusal loading during function.

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• Primary impression made with impression compound

• Special tray made using shellac base plate. And its periphery are 1/8th inch shorter than denture outline.

• Second Impression is made in the special tray using compound

• Bite rims with uniform occlusal surfaces are then made.

• Areas to be relieved are softened and the impression is inserted in mouth and held under biting pressure for one or two minutes

• Borders are molded by asking the patient to perform functional movements

• The PPS was obtained by making the patient swallow, under biting pressure.

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Advantages

• Better retention and support during functional movements

• Provide more tissue coverage

Disadvantages

• The pressure applied can overstress the tissues.

• This often resulted in good initial retention but eventual bone resorption and loose dentures.

• Loss of retention during rest due to tissue rebound.

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Minimal pressure theory/ Mucostatic:-

• Described by Addison, 1944 who attributed it to Henry L. Page.

• He applied Pascal’s Law to soft tissues “Any pressure applied to aconfined fluid is transmitted undiminished in all directions”.

• Mucosa being more than 80% water, will react like a liquid in a closedvessel & cannot be compressed.

• The impression material should record, without distortion, every detail ofthe mucosa denture would fit all minute elevations & depressions.

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• Demanded that a metal base be used instead of acrylics

• This theory has regarded interfacial surface tension as the only important

retentive mechanism.

• Did not use conventional flanges (did not resist vertical displacement).

• Dykins (1947) recommended a short lingual flange to resist lateral

displacement.

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• High regards for the tissue health and preservation

• Good stability due to close adaptation of denture bases

• Less tissue coverage

• Reduced retention

• Lack of border-moulding reduces effective border seal

• Lack of border seal permits food lodgment

• Compromised aesthetics due to short denture flanges

• Tissue variations at the time of impression making and insertion may affect the results.

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Advantages Disadvantages

Selective Pressure Technique (Boucher):-

• Principle – mucosa over the ridge is best able to withstand pressure

mucosa covering midline is thin and has little submucosal

tissue.

• Forces acting on the denture confined to the stress-bearing areas.

• Non stress-bearing areas are relieved and the stress-bearing areas are

allowed to come in contact with the tray.

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Disadvantages of selective pressure technique

•Demands firm, healthy mucosal covering over the ridge.

Hence, it cannot be used in flabby ridges

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MUCOSEAL TECHNIQUE :-

• Stated by Pryor, 1948

• Introduced as a variation to mucostatic technique

• Anterior lingual border molded by the floor of the mouth with the tongue in repose

• Tray extended horizontally backward, over sublingual glands towards the tongue to achieve a border seal

• Benefit of minimal pressure, provides maximum extension of denture borders & maximum denture bearing area coverage.

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Impression by the use of subatmospheric pressure– Milo V. Kubalek, Bert C. Buffington (1966)

• The objective of this technique is to reduce the stress onany given tissue by increasing the load bearing area.

• To realize the idea, the form of tissues must be recordedboth vertically and laterally so that all surfaces can bear anequal load and vacustatic technique is an attempt toachieve this.

• When a controlled partial vacuum is established, animpression tray specially built for the patient is maintainedin the mouth without direct mechanical support of anykind.

• The difference between subatmospheric pressure withinthe tray and atmospheric pressure outside is all thatretained the impression in a static position.

• It denotes the equilibrium of forces which results when acontrolled vacuum is established.

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Open mouth impressions:-

• Made with a tray that is held by the dentist.

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Advantages

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.

Closed mouth impressions:-

• Supporting tissues are recorded in functional relationship.

• Requires wax occlusal rims.

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• Interferences of tray handles

and operator’s finger is

eliminated.

• Time saving -- Border molding, final impression, jaw relation (tentative/final) can be completed in 1 time.

• Rebound of the tissues during rest leads

to denture displacement.

• Tendency for over-extension or under-

extension

• Fatiguing to the dentist and patient.

• A constant pressure is exerted over

tissues, hence blood supply is

compromised leading to ridge

resorption.

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Advantages Disadvantages

• Hand manipulation

The contour of the denture borders may be obtained by the dentist with the use of manual manipulation of the lips and cheeks 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.

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Depending on Manipulation :-

(1) Diagnostic Impression :-

• The negative replica of the oral tissues used to prepare a diagnostic cast.

• Used for study purposes like measuring the undercuts, locating the path

of insertion.

• Is made as a part of treatment plan and to estimate the amount of pre-

prosthetic surgery required.

• Can be used for tentative jaw relation and to evaluate the inter-arch

space. 43

Depending on the purpose of the impression

(2) Primary Impression :-

• An impression made for the purpose of construction of a special tray.

• There should be at least 6mm clearance between the stock tray and the

ridge for materials used in making primary impression.

(3) Secondary Impression:-

• Making the wash impression.

• Developing the posterior palatal seal.

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(A) Selection of Impression material :-

• The material is selected according to the clinical findings,

availability, which in turn influences the technique as well

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• The beginning of good impression starts with the selection ofthe correct stock tray.

(B) Selection of Impression tray :-

Selection of maxillary stock

Tray :-

• Width and height of the vestibular spaces

• Posteriorly - cover the Hamular notches & vibrating line

• Anteriorly - labial notch should coincide with labial frenum providing sufficient clearance for the impression material

• Tray under extended –

• Tuberosities

• Distobuccal areas.

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Selection of mandibular

stock tray :-

• Posteriorly the tray should cover the retromolar pad

• Anteriorly should be centralized with labial frenum with adequate clearance

• Tray under extended –

• Retromolar pad or in

• Retromylohyoid fossae.

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(C) Selection of impression technique :-

• Clinical findings

• Availability of the materials

• Experience of the dentist

• Patient related factors

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Operator position for maxillary impression

Correct

49

Incorrect

Operator position for Mandibular Impression

50Correct Incorrec

t

Making the preliminary impression

Tray should be adjusted by bending

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Selection of stock tray Position borders at

hammular notches

Lift the tray anteriorly, 3-5 mm space for

impression material

Border of the tray

should be cut if

required

Borders should be

smoothened

Material

Manipulation

(hot water bath

at 140F)

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Placing the tray in the patients mouth.

Performing Movements to mold the material.

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• Impression compound is softened in a hot water bath at 140°F.

• After kneading it is loaded on to the tray and shaped roughly to

the shape of the ridge with the fingers.

• The distolingual flange areas can be molded with fingers to

simulate the final impression.

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Mandibular 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.

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• 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.

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Different Techniques

Modified stock tray -

Type II impression compound Double

thickness or reinforced

shellac base plate

Sprinkle-on method for acrylic resin

traysFinger adaptation

Dough method for acrylic resin

trays

Vacuum-formed

thermoplastic resin trays

Visible light cure resin

trays

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Special Tray :-

An individualized impression tray made from a cast recovered from a preliminary

impression. It is used in making a final impression (GPT 8 )

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 59

Checking for tray extensions

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Tray Inserted In the patient’s

mouthLip and cheek are reflected and the borders

are observed

Over-extensions are trimmed

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Tongue is Protruded Lateral movements performed Over-extensions are trimmed ;

Borders are smoothened.

If tray displaces =

indicates contra-lateral

side over extension

If tray raises posteriorly

distolingual flange need

adjustment.

Border molding (Peripheral tracing , Muscle trimming)

• Border molding materials include:

• Modelling compound sticks (Green Stick)

• Polyether impression paste

• Tissue conditioners

• Auto polymerizing acrylic resin

• Impression waxes

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Methods of border molding

Labial and Buccal borders

Smiling whistling grinning

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(1) Functional method :-

Normal functional movements mold the borders in harmony with muscle action

Buccal frenum and Buccal

borders

Sucking

Lingual borders

Licking the lips and tongue movements

Lingual border and Floor of

mouth

Swallowing

Distobuccalborders

Opening, closing and side to side

movements

(2) Digital manipulation :-

• Dentist manipulates the lips and cheeks of the patient to simulate the influence of these on the denture borders.

• Easy ; does not require much of patient cooperation.

• Influenced by the direction of movement and the force applied.

(3) Combined :-

• Border molding is usually done by a combination of digital manipulation by the dentist and functional movements by the patients.

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Steps in Sectional border molding

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Softened compound added along dry

borders of required segment

Cheek outward, downward and

inward

Softened again with alcohol torch.

Tempered in warm water bath.

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Labial Border Molding

outward, downward and inwardsMolding the Frenum

Compound placed on posterior border. Tray seated in mouth with firm pressure.

Compound placed on posterior border

71Compound added on buccal border

The tray gently seated in place.

The borders should be smooth,round

and symmetrical

Compound placed on labial border

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Labial Border Molding

outward, upward and inward

Lingual Border Molding Movements

77

Secondary impression

The final impression material is mixed according to manufacturer’s directions and uniformly distributed within the tray.

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Techniques of Impression making

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One step border molding procedure (polyether) ( Boucher, JPD:1979:41:347 )

Dale E. Smith

81

Adhesive is applied on

the tray

Polyether loaded into a

plastic syringe with slightly less

catalyst

Material is syringed

around the borders & PPS area

Quickly pre-shaped to

proper contours with finger

moistened in cold water

Tray is inserted in the mouth

without material

distortion

Borders checked for

proper extensions

All movements carried out

quickly.

Remove tray when

material is set

Examine for accuracy

Deficient site corrected with a small mix of

polyether material added

to the 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. 82

Impression using new silicone impression materials

I.Hayakawa, I Watanabe(2003)

• Convenient technique for making

impression using newer silicone

materials .

• Heavy bodied silicone material is

used for simultaneous molding of

all borders . (Exahiflex GC)

• Final wash impression is made

with light bodied silicone material

(Exadenture GC)

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Tray 2mm short of tissue

Apply adhesive

Add silicone across border and PPS area

Examine borders ; trim excess material ; Deficient areas remolded

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Advantages :

• Easy to perform

• Recommended for beginners

• Reduction in chair side time

• Silicone material – non irritating, minimal patient discomfort.

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Impression techniques in compromised situations

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Unsupported hyperplastic flabby ridges

Severely resorbed mandibular ridge.

Restricted access to oral cavity.

Unemployed Mandibular

Ridge.

Impression technique for patient with unsupported flabby ridges

87

HobkirkTechnique

Zafrulla Khan Technique

Jone.D. Walter Technique

Splint method by Allan

William.H.FillerTechnique

• The hypermobile tissues should be recorded without distortion with minimum displacement.

• Rest of the tissues are recorded with selective pressure technique.

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Hobkirk technique:

• Single custom tray used.

• Border molding is done in the usual manner.

• Impression - heavy bodied addition silicone

89

Material overlying the hypermobile tissue is cut away and escape

holes made.

Wash impression - light bodied material.

90

Walter Technique: (BDJ 1964:117:392)

• Healthy tissues - zinc oxide eugenol paste

• Undisplaced fibrous tissue - impression plaster.

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Zafurulla Khan Technique: -

92

Splint Technique by Allan Mack

• Exceptionally flabby tissues.

• Special tray made with heavy relief over the flabby area, plaster is mixed

and applied (3mm), 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 it gets removed along with the second

impression

93

Impression Technique For Severely Resorbed Mandibular Ridge

• Cases which lack of ideal amount of supporting structure.

• Encroachment of the surrounding mobile tissues on to the denture

border reduce both stability and retention.

• 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.

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Flange TechniqueDynamic Impression

Technique

Winkler’s Technique(Functional

Reline)Miller’s Technique

Mccold and Tyson Admixed Technique

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Flange technique by Frank Lott and Bernard Levin(JPD 1966:16:394-413)

• 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.

96

Dynamic impression method(G. Tryde, K.Olsson, Jenson)

Dislocating effect of the muscles on improperly formed denture

borders is avoided

Impression material : Irreversible hydrocolloid

• For this mandibular rests are made

on the occlusal aspect of lower record

base with thermoplastic material.

97

• Alginate is mixed and DIRECTLY APPLIED on tissues & then tray is placed

• When material is soft the patient is asked to close the jaw slowly.

• Impression material is shaped by muscular activity.

• Patient should swallow 3 to 4 times in the 10 seconds interval till the material in still moldable state .

98

• Winkler’s technique : -

He described closed mouth

impression technique which uses

tissue conditioners and the final

impression is made with a light body

elastomeric impression material

Miller’s Modification: -Uses mouth temperature waxes instead of tissue conditioners

99

• Complicated by folds of atrophic and/or non-keratinised tissue lying on the ridge

• Impression medium -- admix –

3 parts (red) impression compound

7 parts of greenstick (by weight)

• The working time of this admix is 1–2 minutes and this enables the clinician to mould the tissues to give good peripheral moulding

100

Flat mandibular ridge covered with atrophicmucosa : McCord and Tyson admixed technique

Fabrication of a sectional impression tray and sectional complete denture for a patient with microstomia and trismus: A clinical report (J Prosthet Dent 2003;89:540)

• Maxillary impression inserted into the patient’s mouth in 2 separate pieces: left and right.

• After placement, these pieces were stabilized by means of the acrylic resin block.

• Zinc-oxide eugenol impression.

101

•After the impression paste set, acrylic resin block detached from the

pins, right and the left pieces removed separately by fracturing the

impression material.

•The acrylic resin block was carefully fitted on the pins, and after it

was determined that the fracture line joined smoothly, and cast were

poured

102

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:

103

Old

denture

New denture

• Primary impression - alginate and cast poured.

• Impression compound impression is taken of the cast.

• 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 -- transfer as much of the load as possible to the peripheral parts of the denture bearing area.

104

105

Cocktail Impression Technique: A New Approach to Atwood’s Order VI Mandibular Ridge DeformityPraveen GJ Indian Prosthodont Soc (Jan-Mar 2011) 11(1):32–35

Custom tray with mandibularrests

Custom tray fits against maxillary alveolar ridge at an increased ht.

106

Patient performing functional movements

The final impression

Review of Literature

107

Diurnal variation in palatal tissue thickness –Stephens, Cox, Sharry (1966)

• In this study the variation in palatal thickness atdifferent time of the day is measured.

• A small micrometer was attached to an acrylic resinhood which straddled the upper arch and fitted theocclusal surface of the molar and premolar teeth, thiswas used to measure the diurnal changes in palataltissue.

• The results indicated that the palatal tissues werethickest when the subjects were lying in bed after a fullnight sleep and it starts to shrink in the morning andcontinues in the afternoon. Slight increase in tissuethickness is seen again in the evening.

108

CONCLUSION

The main objective of impression making is to fabricate

dentures having maximum retention and stability

without causing any damage to the supporting

structures. 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.

109

References :

• Zarb GA,Bolender CL,Prosthodontic treatment for edentulous patients- 12th

ed, 13th ed

• Rudd KD, Morrow RM, Dental laboratory procedures complete dentures Vol. l ,2nd ed

• Impression for complete dentures, Bernard Levin

• Complete denture prosthodontics, John J Sharry, 3rd ed

• Essentials of Complete Denture Prosthodontics, Winkler

• A colour atlas of overdentures and complete dentures

• Basic principles in impression making MM Devan J Prosthet Dent 2005;93:503-508

• Complete denture impressions J Prosthet Dent;1965:15(4):603-614

• Jacobson TE, Krol AJ. A contemporary review of the factors involved in complete denture retention, stability, and support. Part I: retention. The Journal of prosthetic dentistry. 1983 Jan 1;49(1):5-15.

110

• Jacobson TE, Krol AJ. A contemporary review of the factors involved in complete dentures. Part II: stability. The Journal of prosthetic dentistry. 1983 Feb 1;49(2):165-72.

• Jacobson TE, Krol AJ. A contemporary review of the factors involved in complete dentures. Part III: support. The Journal of prosthetic dentistry. 1983 Mar 1;49(3):306-13.

• Management of the flabby ridge: using contemporary materials to solve an old problem,BDJ:2006:258:261

• Modified impression technique for hyperplastic alveolar ridges JPD:1971:25:609.

• Physiological determinants of primary impressions for complete dentures,JPD:1984:53:611

• A systematic review of impression technique for conventional complete denture J Indian Prosthodont Soc :10(2):105-111

• A critical analysis of mid century impression techniques for full dentures J ProsthetDent 1951; 472-491

• A critical analysis of complete denture impression procedures: contribution of early prosthodontists in India J Indian Prosthodont Soc ;11(3):172-182

• Impressions for complete dentures using new silicone impression materials Hayakawa, Watanabe; Quintessence International:34:3:177-180

• Fabrication of a sectional impression tray and sectional complete denture for a patient with microstomia and trismus: A clinical report; J Prosthet Dent 2003;89:540

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THANK YOU

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