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Amalgam cavity design

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Amalgam cavity design

  1. 1. Cavity Designs For Amalgam Restorative
  2. 2. Contents Introduction Historical review Definition of Cavity and Cavity preparation Objectives of cavity preparations Factors affecting tooth preparation Nomenclature of tooth preparation Cavity classification Principles of tooth preparations for amalgam Physical , Biological and Anatomical considerations of cavity preparation Armamentarium Class l, ll , lll , lV, V Cavity Designs Tooth preparation for pin amalgam and bonded amalgam Recent concept of cavity design v/s old design Conclusion References
  3. 3. Introduction
  4. 4. Historical Background  1908-G. V Black father of operative dentistry  Established principles of cavity preparation  Dr. Arthur – developed instruments  Charles .E.Woodbury – Cavity design (class lll )  Dr. wedelsteadt --  1868* Dr. Jonathan Taft – bulky chisels  Bur drill (1/32 to !/5 inch )  Hand pieces (foot engine )  Hand pieces (air driven ultraspeed )
  5. 5.  Brief review of class ll Design  1908 - Black ‘s cavity  1924 –Prime  1951 – Markely  1972 – Rodda  1976 – Elderton / Granger
  6. 6. Cavity – Defect in enamel or in enamel and dentin resulting from the pathological process of dental careis ( Acc Charbeneau 3 Edition)  Cavity preparation  Mechanical alteration of a defective, injured or diseased tooth in order to best receive the restorative material which will reestablish a healthy state for the tooth including esthetic corrections where indicated, along with normal form and function (Sturvdent 4 Edition)  Acc Gilmore  Acc Charbeneau
  7. 7. • Objectives of cavity preparation Factors affecting tooth preparation  General factors  Diagnosis  Dental anatomy  Patient factors  Conservation of tooth structure  Restorative material factors
  8. 8. Nomenclature
  9. 9.  Cavity Line angle Point angle  Class l 8 4  Class 2 11 6  MOD 14 8  Class lll 6 3  Class lV 11 6  Class V 8 4
  10. 10. Cavosurface margin
  11. 11. Classification of cavity  G.V .Black classification (Sturvdent 4 Edition) According  Class l – pit and fissure restoration -Restoration on occlusal surface of premolar and molars -Restoration on occlusal two thirds of facial and lingual surfaces of molars -Restoration on lingual surface of maxillary incisors
  12. 12.  Class ll –Restoration on proximal surfaces of posterior teeth  Class lll - Restoration on proximal surfaces of anterior teeth that do not involve the incisal angle  Class lV -Restoration on proximal surfaces of anterior teeth that do involve the incisal angle  Class V – Restorations on the gingival third of the facial or lingual surfaces of all teeth  Class Vl – Restoration on the incisal edge of anterior teeth or the occlusal cusp heights of posterior teeth
  13. 13. Modification of blacks original classification Class Vl - cavities on both mesial and distal proximal surfaces of bicuspids and molars when restored will share a common occlusal isthmus ( Acc charbeneau ) (Markely and bronner ) Class ll – Cavities on single proximal surfaces of bicuspids and molars
  14. 14. According to number of surfaces involved  Simple  Compound  Complex Simple Compound
  15. 15. New cavity of classification Site 1. Pits fissures and enamel on occlusal surface of posterior teeth or other smooth surfaces such as Cingulum pits on anterior Site 2. Approximal enamel immediately below areas in contact with adjacent teeth Site 3. The cervical one third of the crown or,following gingival recession, the exposed root. Acc Graham J mount (1997)
  16. 16. The four sizes of carious lesions  Size 1. Minimal involvement of dentine just beyond treatment by remineralization alone.  Size 2. Moderate involvement of dentine. sound,. That is, the remaining tooth structure is sufficiently strong to support the restoration .  Size 3. The cavity is enlarged beyond moderate.The remaining tooth structure is weakened to the extent that cusps or incisal edges are split, Size 4. Extensive caries with bulk loss of tooth structure has already occurred.
  17. 17. Site1 ,size 0 Site1 ,size 1 Site1 ,size 2
  18. 18. Site1 ,size 3 Site1 ,size 3 Site1 ,size 4 Site2 ,size 0
  19. 19. Site2 ,size 1 Site2 ,size 2 Site 2,size 2
  20. 20. Site 2,size 3 Site 3,size 0 or 1 Site ,size 4 Site 3,size 2
  21. 21. Site 3,size 4 Site 3,size 3
  22. 22. Principles of tooth preparation for amalgam • Initial stages • Final stages - Out line form
  23. 23. Cavosurface margin
  24. 24. Resistance form
  25. 25. Reverse curve
  26. 26. Primary retention form
  27. 27. •Convenience form •Removal of infected dentin Spoon excavator Round bur •Pulp protection •Secondary resistance and retention form •Final procedure
  28. 28. Physical , Biological and Anatomical considerations of cavity preparation Physical considerations Stress bearing area anterior posterior Weak areas Applied mechanical properties
  29. 29. •Biological considerations Irritating agents of tooth preparation •Anatomical properties
  30. 30. Armamentarium used for cavity preparation Basic instruments
  31. 31. Burs 330 245
  32. 32. Class l designs
  33. 33. Class l, design 1  Caries penetration into dentin does not exceed 0.5-1mm  Width- I/4 intercuspal distance  Low caries index
  34. 34. General shape Molar outline Premolar outline
  35. 35. Mesio distal cross section
  36. 36. Pulpal floor of Lower premolar
  37. 37. Class l, design 2 Indication ; caries cones in dentin extend 1mm or more from the DEJ Pulpal floors have different levels
  38. 38. Mesiodistal cross section
  39. 39. Class l, design 3 Indication ; in occlusal one to two thirds of facial and lingual surfaces of molars and on lingual surfaces anterior teeth of General shape
  40. 40. Internal anatomy
  41. 41. Class l, design 4 Applied to molars involving their occlusal surfaces,the grooved part of the facial or lingual surfaces
  42. 42. --Pulpal wall elevated occlusaly --Use in mandibular first molar
  43. 43. Class l, design 5 : Indications  Occlusal surface, most of the facial or lingual surface involved  Occlusal surface is not conducive to retention of restoration  Location of margins  In occlusal cavity mesial and distal margins located at Corresponding axial angles  Gingival margins  –gingival third of the facial or lingual Surface  Pulpal floor – internal boxes (mesial third)
  44. 44. Mesio distal cross section
  45. 45. Class l, design 6 : Includes occlusal surfaces of molars or premolars as well as portion of facial, proximal or lingual surface in form of a table of an entire cusp or section of cusp (marginal ridges ) Gingival margin should extend to allow Occlusal clearance of 1.5-3 mm from Opposing teeth
  46. 46. Class l, Design 7  Involves occlusal , facial and lingual surfaces of molars and premolars  Pins and posts are indicated
  47. 47. Class l, design 8  Endodontically treated tooth  Pulp chamber is retention form
  48. 48. Out line form • Extent of caries • Extent for convenience • Location of gingiva • Convexity of proximal surface • Location and extent of contact areas Resistance form Occlusal loading and its effects
  49. 49. Small cusps Tensile stress Compressive stress Large cusps
  50. 50. Tooth structure Facial and lingual parts of restoration
  51. 51. Groove of restoration facial or lingual parts of restoration
  52. 52. Cusps Crossing ridges
  53. 53. Axial parts of restoration
  54. 54. Design features for the protection of mechanical integrity of restoration Axial wall
  55. 55. Reverse curve
  56. 56. Class ll, Design 1 Conventional design Indications Moderate to large size proximal Lesion with occlusal surface cavity promotes the cavity width of cavity to exceed 1/4 0f intercuspal distance
  57. 57. Proximal box Inverted truncated shape
  58. 58. Tunnel preparation
  59. 59. Class ll, Design 2 (moderate design ) Indications •Moderate to small sized proximal lesions •In stress concentration area •Width not exceeding 1/4 of intercuspal distance General shape width
  60. 60. Bucco lingually Mesiodistaly
  61. 61. Class ll, Design 3 (conservative design ) • Involves primarily proximal surface and very limited part of occlusal Surface, not extending beyond adjacent triangular fossa •Sound occlusal crossing ridges •Minimal loading areas General shape Internal anatomy
  62. 62. Gingival margin Middle third Gingival third
  63. 63. Class ll, Design 4 (Simple design ) •Proximal surface only •Indications; Decay restricted to contacting or proximal surface without undermining marginal ridges Diastema or adjacent tooth is missing
  64. 64. Bucco-lingual Cross section Occlusal-gingival Cross section
  65. 65. Class ll, Design 5 Part of proximal surface ,with a limited access area on facial or lingual surface Indications : •1)Preparation will have 4 surrounding walls •small proximal lesions •Marginal ridge intact •Does not involve contact area 1)Do not have dovetail 2) Preparation will not have surrounding walls •medium proximal lesion 2) Have dovetail
  66. 66. Class ll, Design 6 The occlusal ,proximal and part of the facial or lingual surfaces Indications ; Cusp is missing Badly broken down teeth
  67. 67. Cusp reductions
  68. 68. Class ll, Design 7 (Combinations of class ll with class V ) Shape A : junctions between the class ll and class V via, the Proximal , crossing the axial angles Shape B : via buccal / lingual groove Shape A Shape B
  69. 69. Class ll, Design 8 Two or more surfaces of an endodontically treated tooth does not require post retention
  70. 70. Class lll Amalgam is usually not indicated for anterior teeth due to its esthetic , but distal surface of the cuspid is a unique location General principles are similar to class ll cavity preparation but with emphasis laid on in 5 areas of preparation 1 esthetic concern 2 extension for access 3 stress consideration enamel rod direction Incisal access
  71. 71. Designs of cavity preparation at the distal slope of the cuspid Indications; 1 The lesion does not involve or undermine the distal slope of cupid 2 bulky walls will remain, incisally, after removal of Undermine tissues 3 the labials axial angle is intact 4 the restoration will be directly loaded by vertical forces
  72. 72. Internal anatomy ; Axial convex Depth - .5 from DEJ Retention points : Depth 1 to 2 mm in dentin
  73. 73. Class lV Indications : •Incisal angle is undermined •Labial and lingual walls intact Labio lingual cross section
  74. 74. Modifications
  75. 75. Class V cavity Involvement :smooth surfaces apical to height of contour on facial and lingual surfaces of all teeth eg ; erosion, abrasion , hypoplasia, aplasia  Resistance and retention  To minimize the effects of displacing forces forces grooves occlusal and gingival walls are essential - cementum completely removed - Gingival margins follow the curvature of the furcation
  76. 76. Class V design 1 •lesion are confined to gingival third of the facisal or lingual third of the facial or lingual surface - axial angles intact - no furcation involvement
  77. 77. Class V ,design 2  Lesions on facial or lingual gingival third have involved axial angle  Lesion on facial or lingual gingival third are apical to contact area General shape Mesiodistal cross section
  78. 78. Mesio distal Occluso gingival
  79. 79. Class V Design 3 Indications; Lesion on gingival third facially or linguallly is continuous with isolated decalcifications or lesions occlusal to height of contour Bilateral extension
  80. 80. Class V Design 4 Multiple lesions in gingival third with sound tooth structure separating them General shape
  81. 81. Class V Design 5 Internal anatomy Involves bifurcation or part of it
  82. 82. Class VI
  83. 83. Retention coves
  84. 84. Retention locks
  85. 85. Tooth preparation for pin amalgam
  86. 86. Pin location
  87. 87. Recent concept of cavity designs v/s old design  Black concept :  Extension for prevention :  Outline form – the cause of the problem  The logical alternatives :  Outdated class l cavity design ; Dental update 1985 360-370
  88. 88. Traditional occlusal
  89. 89. Narrow occlusal outline maintains the occlusal tooth structure
  90. 90. Modern Class l Cavity design Occlusal surface
  91. 91. Cavosurface angle
  92. 92. Drawback’s of black’s cavity design 1. It is basically for gold inlays cavity preparation 2. Incorporation of wide occlusal dovetail 3. 1/3 rd intercuspal distance 4. Wide parallel proximal box extending gingival sulcus 5. Damage to adjacent tooth 6. Flat floors
  93. 93. •Conservative design (small is beautiful ) •Tooth fracture :
  94. 94. Enamel –amalgam junction
  95. 95. Outdated class ll cavity design occlusal shape is a wide isthmus necessary ? Retention grooves Gingival floors
  96. 96. Evolution of the Minimal class ll Amalgam cavity Preparation
  97. 97. Modern Class ll cavity
  98. 98. operative dentistry vol 29,525-529 O
  99. 99. Conclusion Although composite resins and crown and bridge restorative dental techniques receive much attention, amalgam will continue to be the most extensively used restorative material for many years to come . If it is used with care in minimal cavities, the restoration, the tooth and the occlusion will all last longer!
  100. 100. References  Marzouk –operative dentistry  Sturdevant- opertive dentistry 4 th edition  Charbeneau – principles and practise of operative dentistry  Black’s operative dentistry  Conservative amalgam restoration jol .of prosth. Dent. 1973  New approaches to cavity design british dental journal 1984  Axial wall revisited j. of operative dent. 1990,42-48  Evaluation of cavity preparation dent update 1985, 357-380  Modern class ll cavity –new zealand dent j 1972,132-137  Coservative class ii cavities j of dental reasearch 1984, 306

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