impressions in complete dentures

GOOD MORNING

IMPRESSIONSIN COMPLETE DENTURES

By:-

Dr SHEBIN ABRAHAM

Post Graduate

DEPT OF PROSTHODON

TICS

CONTENTS1. INTRODUCTION.2. HISTORY.3. DEFINITIONS.4. THE PHILOSOPHY AND GOALS OF IMPRESSION MAKING.5. OBJECTIVES IN IMPRESSION MAKING.6. RELATED ANATOMY.7. PRELIMINARY IMPRESSIONS AND 8. BORDER MOLDING: MATERIALS AND TECHNIQUES.9. THE MANDIBULAR IMPRESSION.10. THE MAXILLARY IMPRESSION.11. CONCLUSION12. REFERENCES.

INTRODUCTION

• Impression making is an ART.• This is a sophisticated procedure which cannot

be leaned easily and described easily.• It requires certain amount of skill and proper

knowledge of the anatomy of oral cavity.

• “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

• Good impressions are basic for construction of good denture. Every phase of denture construction is important.

HISTORY

• Before 18th century no method of making impressions found. Mostly used method then was PAINTING DYE ON RIDGE and a block of ivory or wood was pressed on the ridge the areas in contact was scrapped away until a best fit denture was found.

• In 1711, Matthias Gottfried Purman recorded use of wax.

• 1782- William rae-he got measurement of jaw by a piece of wax pushed against the jaw and he poured the impression using PLASTER OF PARIS.

• 1840- Charles de loude-first impression tray-used tin cups or shapes for impression with wax.

• In 1844, Plaster of Paris was first used as an impression material, the credit for which goes to three dentists— WESTCOTT, DWINELLE AND DUNNING.

• In 1848, gutta percha was first introduced which was placed in boiling water, kneaded and molded same way as wax and immediately inserted firmly into mouth.

• 1874 – Greene brothers J W Geeene William Greene – impression compound

• 1930s – Ward and Kelly – first ZOE impression• 1938- Henry Page –mucostatic impression concept.• 1940s – Write and Denen – first alginate impression• 1950s – elastomeric impression materials .

DEFINITIONS• IMPRESSION:

A negative likeness or copy in reverse of the surface of an object . (GPT 8)

• 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.

• PRELIMINARY IMPRESSION: A preliminary impression is an impression made for the purpose of diagnosis or for the construction of a tray

• Border molding:- The shaping of impression material by manipulation or action of muscles adjacent to it.

• FINAL IMPRESSION: A final impression is an impression for making the master cast .

• IMPRESSION MATERIAL: Any substance or combination of substances used for making an impression or negative reproduction.(GPT 8)

THE BASIC REQUIREMENT OF IMPRESSION MAKING:-

1. Knowledge of oral anatomy2. Knowledge of basic reliable

technique3. Knowledge and understanding

of materials4. Skill5. Patient management

OBJECTIVES IN IMPRESSION MAKING:-

Preservation of Alveolar

Ridge

Retention

Stability

Support

Esthetics

1. PRESERVATION OF THE ALVEOLAR RIDGES

• “ It is more important to preserve what already exists than to replace what is missing”

M M Devan’s dictum

• In impression making covering as much of the supporting area possible

2. Support

• Def:- “It is the resistance to vertical forces of mastication and to occlusal or other forces applied in the direction towards the basal seat.”

• Alveolar ridge never meant for bearing masticatory forces utilize as much area as possible without interfering in function.

• Areas of support–primary stress bearing – secondary stress bearing– slight

Primary stress bearing area:-

Areas of edentulous ridge that are at right angles to occlusal forces and usually do not resorb easily. Maxillae: – posterior ridges – flat area of palate.

Mandible:– buccal shelf area,– posterior ridges and– the pear shaped pad.

Secondary stress bearing area:-

Edentulous ridge right angle or are parallel to occlusal force.Eg; the anterior ridge resorb faster rate than the posterior areasMaxillae: – anterior ridge and all ridge slopes.

Mandible: – anterior ridge and all the ridge slopes.

• Slight: - Areas of very displaceable tissues. Ex; all the vestibular area that provides very little support but are needed for very important peripheral seal.

3. RETENTION

• Def:- It is the resistance of denture to removal in a direction opposite to that of its insertion. Retention resists the adhesiveness of foods, force of gravity, and the forces associated with the opening of the jaws.

Factors affecting retention:-1. Adhesion.2. Cohesion .3. Interfacial surface tension.4. Mechanical locking

undercuts.5. Peripheral seal and

atmospheric pressure.6. Oral and facial musculature.

1. Adhesion:-– it is the physical attraction of unlike molecules.– mucous membrane saliva denture.– the quality of retention depends upon :-

• Close adaptation of denture.• Size of denture bearing area.• The type of saliva.

– Thin but containing some mucous good adhesion.– THIN WATERY– THICK ROPY

2. Cohesion:-– it is the physical attraction

between like molecules. – It is formed by the thin layer of

saliva present below the denture base.

3. Interfacial surface tension:-– It is the resistance to separation

between two parallel surfaces that is imparted by a film of thin liquid between them

– dependent on the ability of the fluid to wet the surrounding material

– high surface tension less wetting and vice versa.

– Denture has high surface tension so decreased wetting by saliva.

– But the pellicle formed on the denture decreases the surface tension and increases the wetting.

– It is based on capillary action – Close adaptation of denture base thin saliva film

by capillarity increases contact.

4. Peripheral seal and Atmospheric pressure:-– It is the positive contact of the entire periphery of

the denture base to the resilient tissues that outline the basal seat.

– Any dislodging forces are resisted by the atmospheric pressure of 14.7 lb/in2

5. Oral and facial musculature:- – These are supplementary retentive forces.– Teeth are arranged in neutral zone.– The denture flanges are shaped accordingly(Fish)– Brill, Trude .

• Mechanical factors:-1. Undercuts.2. Retentive springs.3. Suction discs.4. Magnetic forces.5. Denture adhesives.

4. STABILITY

• Def:- “It is the ability of denture to withstand horizontal forces.”

• Factors affecting stability:-1. Height of ridge.2. Quality of soft tissue.3. Occlusal plane.4. Teeth arrangement.5. Contour of polished surface.

5. AETHETICS

It is one of the prime factors in complete dentures.

Thickness of denture flange for esthetics. So impressions should be made accurately.

THEORIES OF IMPRESSION MAKING

1. Based on the amount of pressure used.2. Open and closed mouth.3. Hand manipulations or functional movements.4. Type of tray.

• Based on the amount of pressure used:1. Mucostatic impression technique2. Mucocompressive impression technique.3. Selective pressure impression technique.

1. Mucostatic or passive impression-• proposed by Henry Page and Richardson.• It is made with oral mucous membrane and jaws in

normal relaxed position.• Border moulding is not done.• Impression is made with oversized trays with

impression plaster.• Good denture stabilityDisadvantages;-• poor retention, retention only because of

interfacial surface tension and has lack of peripheral seal.

2. Mucocompressive impression technique:-– Proposed by Greene – Made with waxes, impression compound etc.– Dentures made with this technique rebound back

at rest.– But at function constant pressure is applied can

decrease circulation, leading to RRR.

3. Selective pressure technique:-– Proposed by Boucher.– Impression extended as much denture bearing

area as possible, except the limiting structures.– Forces only on stress bearing area.– Made by using special tray .– With use of relief wax.

• Based on technique:-1. Open mouth technique.2. Closed mouth technique.

1. Open mouth technique:-• Impressions are made with a tray

that is held by the dentist.• The impression is made with mouth

made open wide.

2. Closed mouth technique:-• Wax occlusal rims made on

preliminary cast.• Jaw relation border moulding and

final impression with mouth closed, clenched with patient performing function movement.

• Time saving but overextension can be created.

• Hand manipulated or functional movements:-

–Hand manipulated:-• Border moulding is done and impression is

made with the hands of the dentist.– Functional movements:-• The functional movements are done by the

patient like sucking, grinning, licking, swallowing etc.• Chase and Trude introduced dynamic

impression technique.

RELATED ANATOMY

• Maxillary landmarks.• Mandibular landmarks.

MAXILLARY LANDMARKS.

LIMITING STRUCTURE:--LACIAL FRENUMLABIAL VESTIBULEBUCCAL FRENUM.BUCCAL VESTIBULE.HAMULAR NOTCH POSTERIOR PALATAL SEAL

SUPPORTING AREAS:-POSTERIOR SLOPES OF HARD PALATE.MAXILLARY TUBOROSITIESRESIDUAL RIDGERUGAE

RELIEF AREAS:INCISIVE PAPILLAEMID PALATINE RAPHEFOVEA PALATINI

MANDIBULAR LANDMARKS

Limiting structures.LABIAL FRENUMLABIAL VESTIBULEBUCCAL FRENUMBUCCAL VESTIBULELINGUAL FRENUMALVEOLOLINGUAL SULCUSRETROMOLAR PAD.

SUPPORTING STRUCTURE:-BUCCAL SHELF AREARESIDUAL ALVEOLAR RIDGE

RELIEF AREA:GENIAL TUBURCLESMENTAL FORAMENTORUS MANDIBULARISCREST OF RIDGE

Steps in making an impression

1. Preliminary examination of the patient2. Seating the patient3. Selection of the tray 4. Selection of the material5. Making primary impression 6. Border molding

7. Making secondary impression

1. Preliminary examination of the patient:-–A complete case history and thorough

clinical examination should be done.

– Factors that can complicate impression making should be identified (flabby ridge, atrophic ridge).

– Patient education.

Seating of the patient Position of the operator for maxillary impression

Position of the operator for mandibular impression Improper position

3. Selection of the tray:-– “A journey of a thousand miles

begins with a single step”- Lao-tzu

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

• Too large – distort the tissues around the borders of the impression and pull the soft tissue away from the bone

• Too small – border will collapse inward on to the ridge

4. Selection of the material– Alginate is the preferred material to make

preliminary impression.– But impression compound can also be used.– A heavy consistency alginate should be used to

record the ridge anatomy.– For alginate 2-3mm gap between tray and

tissue.– For compound 5-6 mm gap

5. Making an impression:-

Preliminary impression-– Stock tray should be beaded at borders with

boxing wax in order to prevent escape of material.– The objective is to obtain a preliminary impression

that is slightly overextended around the borders.

PRIMARY IMPRESSION IN ALGINATE.

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 ray should be short of tissue reflection.

6. Adequate clearance in frenal areas.

7. Tray should be smoothened.

10. Tissue stop in central portion of tray.

8. Deficient borders corrected by adding utility wax.

9. Tray extension in buccal space and tissue side of posterior border.

11. Location of hamular notches. 12. Mark the vibrating line.

13. Some alginate to be placed in vestibule.

14. Alginate to be placed in deepest part of palate.

15. Tray to be rotated into the mouth and seated first at the back of the mouth.

16. Upper lip elevated.

17. Tray is held in the mouth.18. Labial and buccal borders to

be molded.

19. Completed maxillary primary impression with rounded and molded peripheries.

Mandibular alginate impression

3 . Tray should cover retromolar pad and rest against external oblique ridge.

1. Metal edentulous tray 2. Identification of Retromolar pad.

4. Bending and cutting the tray for adjustment.

5. Adding utility was to extend lingual border.

7. Patient told to do tongue movements.

6. Patient told to raise the tongue and tray is rotated in the mouth.

8. Gently mold the labial and buccal areas.

Completed Mandibular Primary Impression

Alginate impression in compound tray.

3. Compound placed in the tray.

1. Modeling compound. 2. Softened in water bath and kneaded.

ALTERNATIVE TECHNIQUE FOR PRIMARY IMPRESSION

5. Should cover mylohyoid ridge and external oblique ridge.

4. Molded with fingers to ridge form.

6. Gently warmed over a flame. 7. Before insertion, tempering in warm water bath.

9. Patient instructed for tongue movements and to purse lips.

8. Tray should be gently seated.

11. Any short areas can be remolded.

10. Impression should cover all denture bearing area.

13. Inside surface reduced by 1-2 mm.

12. All borders reduced by 2-3 mm.

14. Thin mix of alginate loaded.

15. Completed preliminary impression made with alginate using a compound tray.

“Applying a thin wash of alginate over the compound impression assists in delineating the residual ridge. Impression compound may not provide good surface detail, and where the residual ridge is resorbed, this technique is useful for distinguishing the crest of the ridge from the sulcus.”

Complete Dentures- A Manual for the General Dental PractitionerHugh Devlin

Preparation for Secondary or Final Impression (Lab Procedures)

Denture outline marked on the primary impression.

MAXILLARY AND MANDIBULAR SPECIAL TRAYS.

BORDER MOULDING:

Armamentarium required:-• Border molding compound• BP handle with blade• Slow speed handpiece• Acrylic bur• #7 wax spatula• Indelible marking sticks• Custom impression trays• Alcohol torch• Water bath

• Most commonly used border molding materials are:-1. Modelling compound sticks.2. Autopolymerising acrylic resin3. Metallic paste4. Elastomeric materials5. Impression waxes.

RECOMMENDED SEQUENCE OF MAXILLARY BORDER MOLDING

1.Borders should be beveled. 2. Vibrating line marked.

3. Tray inserted in mouth. 4. Overextensions trimmed.

8. Softened compound added from hamular notch to buccal space.

5. Tray should be short of 2 mm from base of sulcus 6. Borders should be adjusted.

7. Extra clearance in frenal areas

12. The tray rotated in mouth and cheek gently massaged.

9. Compound molded with fingers.

10. Softened again with a gas torch or spirit lamp.

11. Tempered in warm water bath.

15. To record the frenum patient told to purse the lips.

13. Appropriate molding will have mat surface.

14. Compound added in buccal frenum area.

17. Recording the frenum.16. Molded buccal and labial borders.

19. Excess compound on tissue side trimmed.

18. Compound placed on posterior border.

21. Junction of tray and compound smoothened.

20. Tray seated in mouth with firm pressure.

22. Border molded maxillary custom tray.

RECOMMENDED SEQUENCE OF MANDIBULAR BORDER MOLDING

Secondary ImpressionB) Mandibular

4. External oblique

ridge marked.

1. Tray outline marked 2-3 mm short of denture outline.

2. Custom tray fabricated.

3. Posterior border of tray should cover anterior half of the pad.

5. Pencil mark transferred to fitting surface.

7. Anterior border of the tray adjusted.

6. Tray border should be resting against the ridge.

8. Lingual border adjusted.

Dry the tray. Slowly heat thecompound and apply to area “A” onone side of the tray.

Seat the tray evenly. Define the tray extension by moldingthe lateral border “A” by massaging the cheek and having thepatient pucker and smile.The cheek is lifted outward, upward, inward, backward, andforward to activate movement of the frenum.

Add compound to area “B” (masseter groove region and theposterior border associated with the retromolar pad).

Ask the patientTo close while holding the tray in position, resisting the closure withYour forefingers on the finger rests.

The effect of the masseter muscle on the border of theimpression is recorded by asking the patient to exert aclosing force while the dentist exerts a downward pressureon the tray.

Area “A” and area “B” have been completed and trimmed. Avoiddisplacing the tissues associated with the retromolar pad.

Apply compound to area “C”. Temper, insert and gentlymassage the lower lip. Simulate muscular activity byslightly lifting the lower lip outward, upward, andinward

The anterior lingual flange is molded by asking the patientto protrude the tongue and then to push the tongueagainst the front part of the palate.

This area is molded by asking the patient to lip the upper lip from One corner to other or is asked to touch the cheeks on both sides With the tongue. He also asked to swallow

15. Border molded mandibular tray

With the edge of your knife blade scrape away a thin layer of compound from theborder molded periphery. This will create space for your impression material andavoid excessive tissue displacement.

Impression tray loaded with Zinc oxide eugenol.

•Clearance provided for frenum.

•Tray held gently in place. •Lips and cheek movements to be done as material sets.

• SECOND TECHNIQUE:- ONE- STEP BORDER- MOLDED TRAY:

• Has two general advantages:1. The number of insertions of the tray for maxillary

and mandibular border molding is reduced.2. Developing all borders simultaneously avoids

propagation of errors caused by a mistake in one section affecting the border contours in another.

• The requirements of such a material are that it should:

1. Have sufficient body 2. Allow some preshaping 3. setting time of 3 to 5 min4. Retain adequate flow 5. Allow finger placement of the material into

deficient parts after the tray is seated6. Not cause excessive displacement of the tissues7. Be readily trimmed & shaped

• The following 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 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.

• THIRD TECHNIQUE:- CUSTOM TRAY DESIGN BASED ON PREVIOUSLY WORN DENTURE:

1. The denture is treated like a standard impression, and a stone cast is poured.

2. An acrylic resin tray is made on the cast over a wax spacer that is outlined just short of the borders of the impression.

3. The tray is tried in the mouth and checked for overextensions.

4. The spacer is removed, relief holes prepared, an adhesive is applied and an impression is made with the preferred material.

LANDMARK MOVEMENTS MUSCLE ACTING

1. Labial frenum Elevation of lip upward No muscles

2. Labial vestibule Elevating the upper lip outward downward inwards

Orbicularis oris

3. Buccal frenum Elevating the cheek outward inward downward and backward forwards

Orbicularis orisBuccinattorLevator anguli oros.

4. Distobucaal region Elevating the cheek outward downward and also opening the mandible wide, and moving the mandible side to side

Coronoid process of manibule.

5. Posterior palatal seal area By asking the patient to say ah in unexxagerated manner with his head bent downward

Junction of hard and soft palate.

MAXILLAE :-

LANDMARKS MOVEMENTS MUSCLES ACTING

1. Labial frenum Recorded by elevation of lower lip incisivus

2. Labial flange Recorded by elevating the upper lip and extended it outward, downward inwards

Orbicularis oris, incisive labii inferioris

3. Buccal frenum Recorded by elevating the cheek outward and downward inwards backwards and forwards

Triangularis(depressi anguli oris)Buccinatororbicularis

4. Distobuccal region Recorded by extending the cheek outward inwards upwards

Masseter

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

Ant region: genioglosusMiddle region: mylohyoid.Posterior region: superior cons, palatoglossus

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

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

Masseter on the buccinator

MANDIBLE:-

• Before the final impressions are made the spacer wax is scrapped off.

• The patient is asked to rinse with cold water or mouthwash to remove away the saliva.

• The acrylic margin inside tray left after removing the spacer is trimmed of .

• Relief holes are made in tray.• The patients mouth can be cleaned with

anaesthetic especially at the posterior palate region to temporarily paralyse the salivary gland.

• Sufficient amount of material is loaded and the impression is made.

Completed maxillary final impression.

Primary impression

Completed mandibular final impression

Primary impression

POSTERIOR PALATAL SEAL AREA• Def:- “The soft tissue at or

along the junction of hard and soft palate where the pressure within the physiological limit can be applied inorder to aid in retention of denture”

a) Pterygomaxillary seal areab) Posterior seal area

Methods of recording

• Arbitrary scrapping.• Fluid wax technique or functional

technique• Convention technique

• Arbitrary scrapping.

• Fluid wax technique

• Conventional technique

IMPRESSION PROCEDURES FOR FLABBY RIDGES:

ONE PART IMPRESSION TECHNIQUE (SÉLECTIVE

PERFORATION TRAY).

CONTROLLED LATERAL

PRESSURE TECHNIQUE.

PALATAL SPLINTING

USING A TWO-PART TRAY SYSTEM.

SELECTIVE COMPOSITION

FLAMING.

TWO PART IMPRESSION TECHNIQUE: MUCOSTATIC

AND MUCODISPLACI

VE COMBINATION

A review of prosthodontic management of fibrousRidges R. W. I. Crawford1 and A. D. Walmsley2 BRITISH DENTAL JOURNAL VOLUME 199 NO. 11 DEC 10 2005

• ONE PART IMPRESSION TECHNIQUE (SÉLECTIVE PERFORATION TRAY):-

– Used in cases of decreased mucosal disposal.

• Procedure:-– Preliminary impressions are taken in

stock trays using low-viscosity alginate after appropriate border correction.

– A spaced special tray is fabricated from the primary cast for use with a low viscosity impression material, such as impression plaster, low-viscosity silicone or alginate.

– Pressure on the unsupported, displaceable soft tissue can be minimised further by the use of perforations in the tray overlying these areas

A review of prosthodontic management of fibrousRidges R. W. I. Crawford1 and A. D. Walmsley2 BRITISH DENTAL JOURNAL VOLUME 199 NO. 11 DEC 10 2005

• CONTROLLED LATERAL PRESSURE TECHNIQUE

– Used in fibrous posterior mandibular ridge region.

• Procedure:-– Compound (green stick) is used to record the denture

bearing area using a correctly extended special tray.– A heated instrument is then used to remove the

greenstick related to the fibrous crestal tissues and the tray is perforated in this region.

– Light bodied silicone impression material is then syringed onto the buccal and lingual aspects of the greenstick and the impression gently inserted.

– The excess material is extruded through the perforations and theoretically the fibrous ridge will assume a resting central position having been subjected to even lateral pressures.

A review of prosthodontic management of fibrousRidges R. W. I. Crawford1 and A. D. Walmsley2 BRITISH DENTAL JOURNAL VOLUME 199 NO. 11 DEC 10 2005

• PALATAL SPLINTING USING A TWO-PART TRAY SYSTEM:-– By Osborne in 1960.– Used in anterior maxillary region.

• The aim of this technique is to maintain the contour of the easily displaceable tissue while the rest of the denture bearing area is recorded

A review of prosthodontic management of fibrousRidges R. W. I. Crawford1 and A. D. Walmsley2 BRITISH DENTAL JOURNAL VOLUME 199 NO. 11 DEC 10 2005

• Procedure:-

– Procedure:

• A preliminary impression in a fluid material such as alginate is cast producing a model of a relatively undistorted ridge.

• A 3-4 mm spaced rigid special tray is constructed and used to take a composition impression of the primary cast.

• The impression periphery is carefully softened and functionally trimmed.

• The fibrous part of the ridge can be outlined on the impression surface.

• The composition overlying the firm denture bearing areas is softened with a flame before the tray is seated under heavy pressure, attempting to replicate functional force.

SELECTIVE COMPOSITION FLAMING;-

TWO PART IMPRESSION TECHNIQUE: MUCOSTATIC

AND MUCODISPLACIVE COMBINATION

• Osborne in 1964• Pressure exerted by the tray does not

cause distortion of the mobile tissues.• Procedure:-– The preliminary impressions are taken and

cast. The displaceable tissue can be marked on the impression and transferred to the primary cast.

– A close fitting cold-cured or light-cured acrylic base is constructed so that the flabby ridge area is left uncovered.

• Appropriate border correction is then carried out before an impression of the firm, supported mucosa is recorded in zinc oxide-eugenol or medium-bodied silicone.

• An impression of the displaceable mucosa is then recorded by applying or syringing a thin mix of impression plaster or light-bodied silicone.

IMPRESSION TECHNIQUE FOR SEVERELY RESORBED RIDGES.

• Method:-• The mandibular primary impression alginate in a stock

tray • The primary cast is pour and a tray devoid of spacer or

relief wax is fabricated• the custom tray is adjusted to be 2 mm short of the

functional depth of the labial and lingual sulci. • The crest of the ridge is marked using an indelible pencil

and is transferred to the tray via placement of the tray on the ridge.

• 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.A Technique for Impressing the Severely Resorbed

Mandibular Edentulous RidgeNair K. Chandrasekharan, et al, Journal of Prosthodontics 21 (2012) 215–218

• The tray is seated in mouth labial and lingual borders are border molded with putty

• Areas of overextension indicated by exposure of the tray borders are corrected ,

• A second application of putty is made over the first, and the borders are molded again .

• 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.

CLINICAL FINDING PRIMARY IMPRESSIONS

SECONDARY IMPRESSIONS

TECHNIQUE

Good ridge form Impression compound

Plaster of Paris, zinc oxide/eugenol, alginate or elastomer

ConventionalSound denture supporting tissues

No undercuts

As above but undercutspresent

Impression compound

Alginate or elastomers; depends on degree ofundercuts

Impression technique conventional but plan path of insertion and removal of tray to match that of the proposed denture.

Good ridge form but theupper ridge is displaceable

Alginate Use a two stage impression technique

Controlled minimally displacive impression techniques

Ridge may look satisfactory but consists of fibrous tissue or is non-corticated (e.g. knife-edge) ridge-pain elicited when palpated

Alginate or medium- bodied elastomer

Zinc-oxide/eugenol or light-bodied elastomer

Controlled pressure impression technique

Very atrophic ridges or where optimum peripheral extension is indeterminate

Impression compound

Functional impression method

Modify denture appropriately and add impression material which is molded by functional movements

Suggested Impression Techniques

Complete Prosthodontics-Problems, Diagnosis and Management, Grant, Heath and Mc Cord

CONCLUSION

References.• Hugh Delvin, Complete Dentures- A clinical manual for

the general dental practitioner• Zarb- Bolender, Prosthodontic treatment for Edentulous

Patients- Complete dentures and Implant supported prostheses, 12th edition.

• Impressions for complete dentures- Bernard Levin.• Boucher’s prosthodontic treatment for edentulous

patients- 10th ed.• Boucher’s prosthodontic treatment for edentulous

patients- 12th ed.• Complete Prosthodontics-Problems, Diagnosis and

Management, Grant, Heath and Mc Cord.• A Technique for Impressing the Severely Resorbed

Mandibular Edentulous Ridge Nair K. Chandrasekharan, et al, Journal of Prosthodontics 21 (2012) 215–218

• A review of prosthodontic management of fibrous Ridges R. W. I. Crawford1 and A. D. Walmsley2 BRITISH DENTAL JOURNAL VOLUME 199 NO. 11 DEC 10 2005