Complete denture impressions

Clinical considerations of complete denture impressions for conventional and special cases

1. CLINICAL ASPECTS OF IMPRESSIONS COMPLETE DENTURE PROSTHODONTICS AAMIR GODIL SECOND YEAR P.G. DEPARTMENT OF PROSTHODONTICS M.A.R.D.C.

2. “ A n ideal impression must be in the mind of a dentist before it is in his hand. He must literally make the impression rather than take it ” -M.M. Devan 2

3. IMPRESSIONS IMPRESSION MATERIALS THEORIES OF IMPRESSION MAKING HISTORICAL BACKGROUND PRINCIPLES OF IMPRESSIONS IMPRESSIONS IN COMPROMISED SITUATIONS ANATOMICAL CONSIDERATIONS 3 BORDER MOLDING CLASSIFICATION OF IMPRESSIONS CLINICAL CONSIDERATIONS

4. CONSIDERATIONS 4

5. OBJECTIVES OF IMPRESSION MAKING 5

6. RETENTION 6

7. STABILITY 7

8. SUPPORT 8

9. ESTHETICS 9

10. PRESERVATION OF REMAINING STRUCTURES USE OF SELECTIVE PRESSURE TECHNIQUE FOR MAKING IMPRESSION AVOID OVER-EXTENSION 10

11. IMPRESSION MATERIALS WHICH TO USE AND WHY? 11

12. BEFORE MAKING THE IMPRESSION Examination and conditioning of the patient and the mouth. Complete case history Clinical examination Identifying and correcting adverse conditions Factors that complicate impression making Old denture wearer. 12

13. SELECTION OF IMPRESSION TECHNIQUE Clinical findings Experience of the dentist Availability of materials Patient related factors Time Undercuts Old denture wearer 13

14. WHAT ARE THE OPTIONS? Preliminary impression materials: impression compound alginate Final impression materials: a lginate silicon based elastomers zinc-oxide eugenol impression paste impression plaster tissue conditioners waxes 14

15. IMPRESSION COMPOUND Easily correctable Can be border molded Not influenced by saliva Can be used as impression tray Can be scraped easily to provide relief Viscous Cannot record fine details Compound sticks used for border molding Inelastic 15

16. ALGINATE Elastic Primary and final impression Records good details Not correctable but easily remade Not dimensionally stable Does not adhere to tray 16

17. ELASTOMERIC IMPRESSION MATERIALS Elastic Fine details Hydrophobic Adhesive required Available in different viscosities Dimensionally stable Cannot be adjusted after set Prolonged setting time 17

18. ZINC OXIDE EUGENOL IMPRESSION PASTE Rigid and inelastic Adheres to tray Flows readily and records fine details Burning sensation and tissue irritation Dimensionally stable B ulk of the impression is minimal Flaking or breaking during trimming 18

19. IMPRESSION PLASTER Minimal pressure technique Flows readily and records fine details Rigid Wash impression Absorbs saliva Dimensionally accurate with anti expansion solution 19

20. TISSUE CONDITIONERS Functional impression Relatively expensive 20

21. WAXES Flow at mouth temperature Exert pressure Fine details not recorded Corrections can be made 21

22. IMPRESSIONS FOR COMPLETE DENTURE FABRICATION HOW? 22

23. PATIENT- OPERATOR POSITIONS 23 MAXILLARY MANDIBULAR

24. 24 TRAY SELECTION POSITION BORDERS AT HAMULAR NOTCH CHECK CLEARANCE AT FRENAL AREAS ADJUST THE TRAY USING PLIERS SMOOTHEN THE TRAY BORDERS

25. 25 TRAY BUILD-UP USING UTILITY WAX

26. FOR MAXILLARY ALGINATE IMPRESSION 26

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28. MANDIBULAR ALGINATE IMPRESSION 28 MARK RETROMOLAR PAD AREA AND ENSURE TRAY EXTENSION

29. 29 PATIENT ASKED TO DO TONGUE MOVEMENTS GENTLY MOLD LABIAL AND BUCCAL AREAS PATIENT ASKED TO RAISE THE TONGUE AND TRAY IS ROTATED AND PLACED

30. IMPRESSION USING IMPRESSION COMPOUND 30

31. 31 ALGINATE WASH IMPRESSION

32. COMMON FAULTS MANDIBULAR Insufficient depth in posterior lingual sulcus Insufficient depth in lingual, labial and buccal sulci Edge of the tray showing through the impression An asymmetrical impression MAXILLARY Deficiency in the midline of palatal vault Excess material extending beyond posterior palatal border of the tray Insufficient depth in one or more region of sulci Tray flange exposure 32

33. PREPARATION FOR FINAL IMPRESSION 33

34. 34 CHECKING TRAY EXTENSIONS Visual examination The diagnostic impression Correction of over extension Correction of under extension

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37. TISSUE STOPS Prevent seating of the tray too superiorly or posteriorly Stabilize the tray Uniform thickness of the material Molar or cuspid areas 37

38. BORDER MOLDING The shaping of the border areas of an impression material by functional or manual manipulation of the size of the vestibule . Materials: Modelling compound sticks Auto-polymerizing acrylic resin Metallic pastes Elastomeric materials Impression waxes 38

39. REQUIREMENTS: Have sufficient body Allow some pre-shaping of the borders Setting time 3-5minutes Retain adequate flow when seating in the mouth Allow finger placement of the material in to deficient parts after seating of tray Not cause excessive displacement of tissues Readily trimmed and carved so that excess material can be carved and borders shaped before the final impression is made 39

40. BORDER MOLDING: MAXILLARY 40

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42. BORDER MOLDING: MANDIBULAR 42

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44. TESTS FOR RETENTION MAXILLARY Upward and outward pressure in the incisor region Upward and outward pressure in the premolar region Pulling the upper lip downward MANDIBULAR Protrude the tongue Move tongue in lateral direction Roll tongue back to touch palate Open the mouth. Exerting vertical pull on handle Forward pressure on distal aspect of the handle 44

45. FINAL IMPRESSION PREPARATION Removing the relief wax Removing spacer wax Escape holes Reducing the borders Applying adhesive Protecting the mouth Drying the mouth Instructing the patient MAKING THE IMPRESSION Mixing Loading Seating Removing the impression Inspecting Correcting Remaking 45

46. BORDER MOLDING AND ANATOMIC CONSIDERATIONS 46

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48. 48 KNOWING THE ANATOMY (MAXILLARY)

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50. 50 KNOWING THE ANATOMY (MANDIBULAR)

51. 51 MAKING THE RIGHT DECISION

52. SPECIAL CONSIDERATIONS FOR IMPRESSION MAKING IN COMPLETE DENTURE PROSTHODONTICS 52

53. IMPRESSION TECHNIQUES FOR RESORBED RIDGES 53

54. PROBLEMS ENCOUNTERED IN MAKING AN IMPRESSION OF RESORBED MANDIBULAR RIDGE Mucosa : thin and atrophic Inadequate denture bearing areas Attachment of muscles near the crest of the ridge Interference of tongue 54

55. FINAL IMPRESSION TECHNIQUES TO MANAGE RESORBED MANDIBULAR RIDGES: Conventional technique Functional impression technique Elastomeric technique Admix technique Cocktail technique All green technique Flange technique Modified Functional Impression Technique

56. 1.CONVENTIONAL TECHNIQUE ( Boucher) Border moulding done with green stick compound Final impression made using zinc oxide eugenol impression paste. Impression recorded using open mouth technique .

57. ADVANTAGES: 1.Easy handling 2.No dimensional change 3.Reproduction of fine details . DISADVANTAGES: 1.Short manipulation time 2.Hardens quickly before the functional movements can be recorded .

58. 2.FUNCTIONAL IMPRESSION TECHNIQUE ( W inkler) C losed mouth functional technique.

59. ADVANTAGES 1.Overall denture has better surface contact 2.Improved retention 3.Interference due to tray handling is eliminated 4.Less chances of over and under extension as the movements are performed by the patient DISADVANTAGES 1.Restriction of tongue movement therefore inaccurate recording of lingual border. 2.Completely depended on patient.

60. 3.ELASTOMERIC IMPRESSION TECHNIQUE:

61. ADVANTAGES: 1.Single step border moulding. 2.Minute details are recorded due to the use of light body addition silicone. DISADVANTAGES: 1.Single step border moulding is technique sensitive 2.Comparatively expensive.

62.   4.ADMIX TECHNIQUE ( Mc Cord and Tyson ) This reduces the potential discomfort arising from atrophic mucosa . Impression compound and green stick compound are mixed in the ratio of 3 : 7 parts by weight are placed in a bowl of water at 60 degrees Celsius. RATIONALE Viscous admix of impression compound and green stick compound removes the soft tissue folds and smoothens them over the mandibular bone.

63. ADVANTAGES: 1.Functional position of muscle are recorded in single step. 2.Less chair time and economical. DISADVANTAGE: 1.Overextension of impression Kneaded to a homogenous mass that provides a working time of about 90 seconds. Wax spacer is removed; this homogenous mass is loaded and patient is made to do various tongue movements.

64.   5.COCKTAIL TECHNIQUE After making the primary impression , customized custom tray is made with self cure acrylic resin. Rest are made on the custom tray with increased vertical height , and impression compound softened and placed top of mandibular rest. Patient is asked to close the mouth , so that mandibular rests fit against the maxillary alveolar ridge.

65. This would help in stabilisation of the tray during impression making as it would prevent antero-posterior and medio-lateral displacement of the tray. Impression and green stick compound are mixed in the ratio of 3:7 and loaded on the tissue surface. Patient is asked to perform functional movements and in this way impression is recorded . ADVANTAGES: 1.Dislocating effect of muscles on the tray is avoided. 2.Rest made on the mandibular tray prevents displacement of the tray.

66. 6.  ALL GREEN TECHNIQUE Green stick compound is kneaded to a homogenous mass and is loaded on the special tray and border movements are done. Final impression made using zinc oxide eugenol paste.

67. 7.FLANGE TECHNIQUE (Lott And Levin) Labial and lingual borders are manipulated using Adaptol wax. Removal of excess wax from the inner surface of the tray. Carbide bur used to remove 1mm of resin from the crest of the ridge. Tray cleaned and painted with rubber base adhesive. Final impression made using polysulfide impression material.

68. 8. MODIFIED FUNCTIONAL IMPRESSION TECHNIQUE ( CHANDRASHEKHARAN et AL) 69 Preparation of acrylic custom tray on primary cast with a window over Atwood’s Class IV ridge. Fabrication of a wax handle over the window. Border molding of buccal and lingual flanges with A-silicone putty. Trim the excess and overextended borders Remove the wax handle Inject light body A-silicone through the window Final impression Chandrashekharan et al. A Technique for Impressing the Severely Resorbed Mandibular Edentulous Ridge. Journal of Prosthodontics 00 (2011) 1–4 c 2011 by the American College of Prosthodontists

69. IMPRESSION TECHNIQUES FOR FLABBY RIDGES 70

70. A so-called ‘fibrous’ or ‘flabby’ ridge is a superficial area of mobile soft tissue affecting the maxillary or mandibular alveolar ridges. It can develop when hyperplastic soft tissue replaces the alveolar bone and is a common finding, particularly in the upper anterior region of long term denture wearers. 71

71. APPROACHES TO MANAGEMENT OF FLABBY TISSUE 72

72. There are two impression principles which are reported to overcome this problem : Mucodisplacive impression technique: with the aim of compressing the loose flabby tissue to allow functional support from it by replicating the contour of the ridge during compression by occlusal forces . Mucostatic impression technique: which aims to achieve support from the other firm areas of the arch and maximizes retention . 73 R. W. I. Crawford, A. D. Walmsley. BRITISH DENTAL JOURNAL VOLUME 199 NO. 11 DEC 10 2005

73. One Part Impression Technique (Sélective Perforation Tray) 74 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 Lamb D J. Problems and solutions in complete denture prosthodontics. pp 57-60. London: Quintessence , 1993.

74. Controlled Lateral Pressure Technique 75 Grant A A , Heath J R, McCord J F. Complete prosthodontics : problems, diagnosis and management . pp 90-92. London: Wolfe, 1994.

75. Palatal Splinting Using A Two-part Tray System 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. Devlin H. A method for recording an impression for a patient with a fibrous maxillary alveolar ridge. Quint Int 1985; 6: 395-397.

76. Selective Composition Flaming 77 By performing the impression in this way , the original relatively undistorted shape of the fibrous tissues is retained while the tissues more capable of functional denture support are recorded in a displaced state. Lamb D J. Problems and solutions in complete denture prosthodontics. pp 57-60. London: Quintessence , 1993.

77. Two Part Impression Technique: Muco -static And Muco-displacive Combination 78 Osborne J. Two impression methods for mobile fibrous ridges. Br Dent J 1964; 117: 392-394

78. Modifications: Window Technique: An alternative , described by Hobkirk , McCord and Grant, involves removal of acrylic from a complete special tray creating a window over the displaceable area . The advantage of a window design means that the appropriate border correction can be undertaken and checked around the entire sulcus before the second stage of the impression is completed. 79

79. 80 Cage Technique : Used for multiple dispersed areas of fibrous tissue where multiple small windows are made.

80. Modified Fluid Wax Technique (FOR RESORBED + FLABBY RIDGES) : 81 Tan et al. Modified fluid wax impression for a severely resorbed edentulous mandibular ridge. J Prosthet Dent. 2009;101:279-282

81. IMPRESSION TECHNIQUES FOR LIMITED MOUTH OPENING AND MICROSTOMIA 82

82. 83 Baker et al (J Prosthet Dent 2000;84:241-4 .) Hydrocolloid primary impression using sectional plastic stock tray. Fabrication of sectional light cure custom tray segment by segment connected by horizontal hinge. Elastomeric impression is made with first half of the tray followed by the second part. Approximate both the sections while making the second sectional impression and close the horizontal hinge. Allow the impression to set. Remove the impression in sections. Evaluate- reassemble- pour

83. Colvenkar S Journal of Prosthodontics 19 (2010) 161–165 c 2009 84

84. Moghadam BK (J PROSTHET DENT 1992;67:23-5.) Make an impression of the left side of the mouth with irreversible hydrocolloid by using tray No. 1 Pour this impression with dental stone as soon as possible . Separate the cast from the impression when the stone has set. Make a 45-degree bevel with a sharp knife at the medial border of the cast anteroposteriorly to increase the contact area of this cast with the next pour Make an impression of the right side of the arch with irreversible hydrocolloid by using tray No. 2. Position the cast made from the first impression in this impression and stabilize the cast in the impression . Pour the impression containing the cast in dental stone. Separate the cast from the impression after the stone has set and trim the borders. 85 McCord JF , Tyson KW, Blair IS. A sectional complete denture for a patient with microstomia . J Prosthet Dent 1989;61:645–7.

85. Luebke RJ J Prosthet Dent 1984;52:135–7 . A plastic tray was chosen by measuring the ridge with calipers and then cut in two sections with a disc with the handle in the larger section. Three building blocks (toy ) (LEGO Systems, Inc., Enfield, Conn) were selected to reapproximate sectional trays as one unit which were fixed to the tray by the help of autopolymerising resin. Depending on whether the patient is dentulous or edentulous, polyether or zinc oxide eugenol paste was used to make impressions. With the larger section tray, impression of two thirds of the arch was made after which the impression was removed from the mouth, allowed to set and trimmed flush the edge of the tray using surgical blade. This was further repeated with second sectional tray and both were joined and poured 86

86. Cura et al J Prosthet Dent 2003;89:540–3. Putty-type impression material can be manually dispensed intraorally to serve as custom trays to make diagnostic maxillary and mandibular impressions . Once the impression putty is placed onto the denture bearing areas , the impression material was border moulded to the appropriate contour. The impression putty custom tray was removed after the material polymerized. Impression material was loaded onto the silicone custom trays and inserted intra orally . 87

87. 88 Mandibular sectional stock tray to be joined with acrylic hook and steel bur at the handle region. A is the metal pin B is the bend to hook around handle C C is bent handle sections D is the metal tubing within acrylic into which A will be fitted E is the fins to approximate tray sections Maxillary sectional tray locked at the handle region with steel pins into tubings and acrylic hook into bent handles. Hegde C. et al Journal of Prosthodontic Research 56 (2012) 142–146

88. 89 Foldable mandibular sectional tray with steel burs and acrylic blocks which are folded while inserting into the oral cavity and opened on the arch to seat on the pins. Anterior and posterior tray sections joined by steel burs

89. IMPRESSION TECHNIQUES FOR PATIENT WITH GAG REFLEX 90

90. General Management and Useful Tips Call well rested patient Avoid patient visits - immediately after meals - early morning appointment Calm environment Continuous reassurance to the patient One technique common to all Shipmon and Massad described it as “CARING ATTITUDE FACTOR”

91. Behavioural Techniques Behaviour modification Objectives : Reduce anxiety and ‘‘unlearn’’ the behaviour that provoke gagging.

92. Singer’s Desensitisation T echnique Also called “marble technique” Involves 7 visits 1 st visit: 5 marbles placed in mouth, patient instructed to keep them for 1 week 2 nd visit: ability to tolerate marbles evaluated 3 rd visit: before making impressions, topical anaesthetic applied , primary impression made, base plates made with a rough finish 4 th visit: lower base plate inserted , 3 marbles placed and a “training bead” 5 th visit: upper base plate inserted , asked to discontinue marbles 6 th visit: patient able to endure the presence of both base plates , occlusal rims constructed Jaw relation taken , try in completed. 7 th visit: completed lower denture inserted first + upper base plate + a training bead. Next upper denture inserted Singer JL. The marble technique : method for treating the hopeless gagger for complete dentures. J. Prosthet . Dent. 1973;8

93. Impression Technique If stock trays are used, a posterior dam can be constructed in the tray using wax or silicone putty. This will help to prevent material exuding from back of the tray. In patients with a history of gagging, consider using a less fluid impression material with faster setting characteristics . Avoid overloading trays and initially seat the tray posteriorly . Use of sectional impression trays

94. IMPRESSION TECHNIQUES FOR NEUTRAL ZONE 95

95. The neutrocentric concept requires that posterior mandibular denture teeth be arranged to occupy as central a location as possible, relative to the denture foundation, without disturbing adequate tongue function This tooth arrangement is said to facilitate mandibular denture stability during occlusal loading The term neutral zone concept was coined by Beresin and Schiesser in 1976 . It is that region where forces imposed by the tongue directed outward are neutralized by inwardly directed forces originating from the cheeks and lips during normal neuromuscular function. 96

96. 97

97. Historically, different terminology has been loosely associated with this concept, including dead zone stable zone zone of minimal conflict zone of equilibrium zone of least interference biometric denture space denture space potential denture space Arranging artificial teeth within the neutral zone achieves 2 important objectives: Prosthetic teeth do not interfere with normal muscle function Normal oral and perioral muscle activity imparts force against the complete dentures that serves to stabilize and retain the prostheses rather than cause denture displacement 98

98. A soft material that can be molded by the action of the tongue, cheek, and lips is used to establish the neutral zone. Modelling compound softened at 65 F is adapted to the top of the lower tray and shaped similar to a wax occlusion rim. The tray and modeling compound are placed in the mouth, and the patient is instructed to swallow. The actions of the muscles and tongue during swallowing mold the soft compound into the neutral zone and shape the polished surfaces of the denture. The modeling compound is allowed to harden in the mouth sufficiently to prevent distortion and is placed in cold water to harden for trimming. The modeling compound is trimmed so that the occlusal plane is established approximately 1 to 2 mm below the lateral border of the tongue when it is at rest. 99

99. SUMMARY 100

100. Thank You 101