Impressions in complete dentures

complete denture impression

1. GOOD MORNING

2. IMPRESSIONS IN COMPLETE DENTURES By:- Dr SHEBIN ABRAHAM Post Graduate DEPT OF PROSTHODONTICS

3. CONTENTS INTRODUCTION. HISTORY. DEFINITIONS. THE PHILOSOPHY AND GOALS OF IMPRESSION MAKING. OBJECTIVES IN IMPRESSION MAKING. RELATED ANATOMY. PRELIMINARY IMPRESSIONS AND BORDER MOLDING: MATERIALS AND TECHNIQUES. THE MANDIBULAR IMPRESSION. THE MAXILLARY IMPRESSION. CONCLUSION REFERENCES.

4. 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.

5. “ 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.

6. HISTORY Before 18 th 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.

7. 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 .

8. 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

9. 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)

10. THE BASIC REQUIREMENT OF IMPRESSION MAKING:- Knowledge of oral anatomy Knowledge of basic reliable technique Knowledge and understanding of materials Skill Patient management

11. OBJECTIVES IN IMPRESSION MAKING:- Preservation of Alveolar Ridge Retention Stability Support Esthetics

12. 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

13. 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.”

14. 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

15. P rimary 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.

16. S econdary stress bearing area:- Edentulous ridge right angle or are parallel to occlusal force. Eg ; the anterior ridge  resorb faster rate than the posterior areas Maxillae : anterior ridge and all ridge slopes. Mandible : anterior ridge and all the ridge slopes.

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

18. 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.

19. Factors affecting retention:- Adhesion. Cohesion . Interfacial surface tension. Mechanical locking undercuts. Peripheral seal and atmospheric pressure. Oral and facial musculature.

20. 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

21. 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.

22. 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.

23. 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 /in 2

24. 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 .

25. Mechanical factors:- Undercuts. Retentive springs. Suction discs. Magnetic forces. Denture adhesives.

26. 4. STABILITY Def :- “ It is the ability of denture to withstand horizontal forces.” Factors affecting stability:- Height of ridge. Quality of soft tissue. Occlusal plane. Teeth arrangement. Contour of polished surface.

27. 5. AETHETICS It is one of the prime factors in complete dentures. Thickness of denture flange  for esthetics . So impressions should be made accurately.

28. THEORIES OF IMPRESSION MAKING Based on the amount of pressure used. Open and closed mouth. Hand manipulations or functional movements. Type of tray.

29. Based on the amount of pressure used : Mucostatic impression technique Mucocompressive impression technique. Selective pressure impression technique.

30. 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 stability Disadvantages;- poor retention, retention only because of interfacial surface tension and has lack of peripheral seal.

31. 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.

32. 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.

33. Based on technique:- Open mouth technique. Closed mouth technique.

34. 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. 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.

35. 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.

36. RELATED ANATOMY Maxillary landmarks. Mandibular landmarks.

37. MAXILLARY LANDMARKS. LIMITING STRUCTURE:-- LACIAL FRENUM LABIAL VESTIBULE BUCCAL FRENUM. BUCCAL VESTIBULE. HAMULAR NOTCH POSTERIOR PALATAL SEAL

38. SUPPORTING AREAS:- POSTERIOR SLOPES OF HARD PALATE. MAXILLARY TUBOROSITIES RESIDUAL RIDGE RUGAE RELIEF AREAS: INCISIVE PAPILLAE MID PALATINE RAPHE FOVEA PALATINI

39. MANDIBULAR LANDMARKS Limiting structures. LABIAL FRENUM LABIAL VESTIBULE BUCCAL FRENUM BUCCAL VESTIBULE LINGUAL FRENUM ALVEOLOLINGUAL SULCUS RETROMOLAR PAD.

40. SUPPORTING STRUCTURE:- BUCCAL SHELF AREA RESIDUAL ALVEOLAR RIDGE RELIEF AREA: GENIAL TUBURCLES MENTAL FORAMEN TORUS MANDIBULARIS CREST OF RIDGE

41. Steps in making an impression Preliminary examination of the patient Seating the patient Selection of the tray Selection of the material Making primary impression Border molding Making secondary impression

42. 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.

43. Seating of the patient Position of the operator for maxillary impression Position of the operator for mandibular impression Improper position

44. 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

45. 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

46. 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.

47. 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.

48. 5. Border of ray should be short of tissue reflection. 6 . Adequate clearance in frenal areas. 7 . Tray should be smoothened.

49. 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.

50. 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.

51. 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.

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

53. Mandibular alginate impression 3 . Tray should cover retromolar pad and rest against external oblique ridge. 1. Metal edentulous tray 2. Identification of Retromolar pad.

54. 4. Bending and cutting the tray for adjustment. 5. Adding utility was to extend lingual border.

55. 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.

56. Completed Mandibular Primary Impression

57. 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

58. 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.

59. 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.

60. 13. Inside surface reduced by 1-2 mm. 12. All borders reduced by 2-3 mm. 14. Thin mix of alginate loaded.

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

62. “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 Practitioner Hugh Devlin

63. Preparation for Secondary or Final Impression (Lab Procedures) Denture outline marked on the primary impression.

64. MAXILLARY AND MANDIBULAR SPECIAL TRAYS.

65. 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

66. Most commonly used border molding materials are:- Modelling compound sticks. Autopolymerising acrylic resin Metallic paste Elastomeric materials Impression waxes.

67. RECOMMENDED SEQUENCE OF MAXILLARY BORDER MOLDING

68. 1 .Borders should be beveled. 2 . Vibrating line marked. 3 . Tray inserted in mouth. 4 . Overextensions trimmed.

69. 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

70. 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 .

71. 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.

72. 17. Recording the frenum. 16. Molded buccal and labial borders. 19. Excess compound on tissue side trimmed. 18. Compound placed on posterior border.

73. 21. Junction of tray and compound smoothened. 20. Tray seated in mouth with firm pressure. 22. Border molded maxillary custom tray.

74. RECOMMENDED SEQUENCE OF MANDIBULAR BORDER MOLDING

75. Secondary Impression B) 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.

76. 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.

77. Dry the tray. Slowly heat the compound and apply to area “A” on one side of the tray.

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

79. Add compound to area “B” (masseter groove region and the posterior border associated with the retromolar pad). Ask the patient To close while holding the tray in position, resisting the closure with Your forefingers on the finger rests.

80. The effect of the masseter muscle on the border of the impression is recorded by asking the patient to exert a closing force while the dentist exerts a downward pressure on the tray.

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

82. Apply compound to area “C”. Temper, insert and gently massage the lower lip. Simulate muscular activity by slightly lifting the lower lip outward, upward, and inward

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

84. 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

85. 15. Border molded mandibular tray

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

87. 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.

88. 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 .

89. The requirements of such a material are that it should: Have sufficient body Allow some preshaping setting time of 3 to 5 min Retain adequate flow Allow finger placement of the material into deficient parts after the tray is seated 6. Not cause excessive displacement of the tissues 7. Be readily trimmed & shaped

90. The following procedure utilizes polyether impression materials for border molding. Place adhesive for polyether impressions on the borders of tray. 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. Thoroughly mix material for 30 to 45 seconds using a metal spatula.

91. 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

92. 9. Remove tray when impression material is set. 10. Examine border molding to determine that it is adequate.

93. THIRD TECHNIQUE:- CUSTOM TRAY DESIGN BASED ON PREVIOUSLY WORN DENTURE: The denture is treated like a standard impression, and a stone cast is poured. An acrylic resin tray is made on the cast over a wax spacer that is outlined just short of the borders of the impression. The tray is tried in the mouth and checked for overextensions. The spacer is removed, relief holes prepared, an adhesive is applied and an impression is made with the preferred material.

94. 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 oris Buccinattor Levator 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 :-

95. 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 ) Buccinator orbicularis 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: genioglosus Middle 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:-

96. 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.

97. Completed maxillary final impression. Primary impression

98. Completed mandibular final impression Primary impression

99. 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” Pterygomaxillary seal area Posterior seal area

100. Methods of recording Arbitrary scrapping. Fluid wax technique or functional technique Convention technique

101. Arbitrary scrapping.

102. Fluid wax technique

103. Conventional technique

104. IMPRESSION PROCEDURES FOR FLABBY RIDGES: 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

105. 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 fibrous Ridges R . W. I. Crawford1 and A. D. Walmsley2 BRITISH DENTAL JOURNAL VOLUME 199 NO. 11 DEC 10 2005

106. 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 fibrous Ridges R . W. I. Crawford1 and A. D. Walmsley2 BRITISH DENTAL JOURNAL VOLUME 199 NO. 11 DEC 10 2005

107. 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 fibrous Ridges R . W. I. Crawford1 and A. D. Walmsley2 BRITISH DENTAL JOURNAL VOLUME 199 NO. 11 DEC 10 2005

108. Procedure:-

109. 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;-

110. 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.

111. 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.

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

113. 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 .

114. 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.

115. CLINICAL FINDING PRIMARY IMPRESSIONS SECONDARY IMPRESSIONS TECHNIQUE Good ridge form Impression compound Plaster of Paris, zinc oxide/eugenol, alginate or elastomer Conventional Sound denture supporting tissues No undercuts As above but undercuts present Impression compound Alginate or elastomers; depends on degree of undercuts Impression technique conventional but plan path of insertion and removal of tray to match that of the proposed denture. Good ridge form but the upper 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

116. CONCLUSION

117. 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, 12 th edition . Impressions for complete dentures- Bernard Levin. Boucher’s prosthodontic treatment for edentulous patients- 10 th ed. Boucher’s prosthodontic treatment for edentulous patients- 12 th 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