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Cavity Designs For Amalgam Cavity Designs For Amalgam RestorativeRestorative
ContentsContents
IntroductionHistorical reviewDefinition of Cavity and Cavity preparationObjectives of cavity preparationsFactors affecting tooth preparationNomenclature of tooth preparationCavity classificationPrinciples of tooth preparations for amalgamPhysical , Biological and Anatomical considerations of cavity preparationArmamentarium Class l, ll , lll , lV, V Cavity DesignsTooth preparation for pin amalgam and bonded amalgam Recent concept of cavity design v/s old designConclusion References
Introduction Introduction
Historical BackgroundHistorical 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 )
Brief review of class ll Design
1908 - Black ‘s cavity 1924 –Prime 1951 – Markely 1972 – Rodda 1976 – Elderton / Granger
Cavity Cavity –– Defect in enamel or in enamel and Defect in enamel or in enamel and dentin resulting from the pathological process of dentin resulting from the pathological process of dental careis dental careis ( Acc Charbeneau ( Acc Charbeneau 3 Edition)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
• Objectives of cavity preparationObjectives of cavity preparation
Factors affecting tooth preparation General factors Diagnosis Dental anatomy Patient factors Conservation of tooth structure Restorative material factors
NomenclatureNomenclature
Cavity Line angle Point angle
Class l 8 4Class 2 11 6MOD 14 8Class lll 6 3Class lV 11 6Class V 8 4
Cavosurface marginCavosurface margin
Classification of cavityClassification 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
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
Class Vl - cavities on both mesial and distal proximal surfaces of bicuspids and molars when restored will share a common occlusal isthmus ( Acc charbeneau )
Modification of blacks original classification Modification of blacks original classification (Markely and bronner (Markely and bronner ) )
Class llClass ll – – Cavities on single proximal surfaces of Cavities on single proximal surfaces of bicuspids and molarsbicuspids and molars
According to number of surfaces According to number of surfaces involvedinvolved
Simple Compound Complex
Simple
Compound
New cavity of classificationNew cavity of classification Site 1. Pits fissures and enamel on occlusal surface of posterior teeth or other smooth surfaces such as Cingulum pits on anteriorSite 2. Approximal enamel immediately below areas in contact with adjacent teethSite 3. The cervical one third of the crown or,following gingival recession, the exposed root.
Acc Graham J mount (1997)
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.
Site1 ,size 0 Site1 ,size 1
Site1 ,size 2
Site1 ,size 3 Site1 ,size 3
Site2 ,size 0Site1 ,size 4
Site2 ,size 2
Site2 ,size 1
Site 2,size 2
Site 3,size 0 or 1Site 2,size 3
Site ,size 4 Site 3,size 2
Site 3,size 4
Site 3,size 3
Principles of tooth preparation for amalgam
• Initial stages • Final stages
- Out line form
Cavosurface margin
Resistance form
Reverse curve
Primary retention form
•Convenience form
•Removal of infected dentin Spoon excavator Round bur
•Pulp protection
•Secondary resistance and retention form
•Final procedure
Physical , Biological and Anatomical considerations
of cavity preparation
Physical considerationsStress bearing area anterior posterior
Weak areas
Applied mechanical properties
•Biological considerations
Irritating agents of tooth preparation
•Anatomical properties
Armamentarium used for cavity preparation
Basic instruments
330 245
Burs
Class l designs
Class l, design 1Class l, design 1
Caries penetration into dentin does not exceed 0.5-1mm
Width- I/4 intercuspal distanceLow caries index
Molar outline Premolar outline
General shape
Mesio distal cross section
Pulpal floor of Lower premolar
Class l, design 2Indication ; caries cones in dentin extend 1mm or more from the DEJ
Pulpal floors have different levels
Mesiodistal cross section
Class l, design 3
Indication ; in occlusal one to two thirds of facialand lingual surfaces of molars and on lingual surfacesanterior teeth of
General shape
Internal anatomy
Class l, design 4
Applied to molars involving their occlusal surfaces,the grooved part of the facial or lingual surfaces
--Pulpal wall elevated occlusaly--Use in mandibular first molar
Class l, design 5 :Class l, design 5 : IndicationsIndications 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)
Mesio distal cross section
Class l, design 6 :Class l, design 6 :Includes occlusalIncludes occlusal surfaces of molars or surfaces of molars or premolars as well as portion of facial, premolars as well as portion of facial,
proximalproximalor lingual surface in form of a table of an or lingual surface in form of a table of an
entireentirecusp or section of cusp (marginal ridges )cusp or section of cusp (marginal ridges )Gingival margin should extend to allow
Occlusal clearance of 1.5-3 mm fromOpposing teeth
Class l, Design 7Class l, Design 7
Involves occlusal , facial and lingual surfaces of molars and premolars
Pins and posts are indicated
Class l, design 8Class l, design 8 Endodontically treated tooth Pulp chamber is retention form
Out line formOut 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
Small cusps
Tensile stress
Compressive stress
Large cusps
Tooth structure Facial and lingual parts of restoration
Groove of restoration
facial or lingual parts of restoration
Cusps Cusps Crossing ridgesCrossing ridges
Axial parts of restorationAxial parts of restoration
Axial wall
Design features for the protection of mechanical integrity of restoration
Reverse curveReverse curve
Class ll, Design 1Class ll, Design 1
Moderate to large size proximal Lesion with occlusal surface cavity promotes the cavity width of cavity to exceed 1/4 0f intercuspal distance
Conventional design
Indications
Proximal box
Inverted truncated shape
Tunnel preparationTunnel preparation
Class ll, Design 2 (moderate design )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
Bucco lingually
Mesiodistaly
Class ll, Design 3 (conservative design )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 shapeInternal anatomy
Gingival marginGingival margin
Middle third Gingival third
Class ll, Design 4 (Simple design )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
Bucco-lingualCross section
Occlusal-gingival
Cross section
Class ll, Design 5Class ll, Design 5
Part of proximal surface ,with a limited access area on facial or lingual surfaceIndications :
1)Do not have dovetail2) Have dovetail
•1)Preparation will have 4 surrounding walls •small proximal lesions•Marginal ridge intact•Does not involve contact area
2) Preparation will nothave surrounding walls
•medium proximal lesion
Class ll, Design 6Class ll, Design 6The occlusal ,proximal and part of the facial or lingual surfaces
Indications ; Cusp is missing Badly broken down teeth
Cusp reductionsCusp reductions
Class ll, Design 7Class ll, Design 7
Shape A : junctions between the class ll and class V via, theProximal , crossing the axial anglesShape B : via buccal / lingual groove
Shape A Shape B
(Combinations of class ll with class V )
Class ll, Design 8Class ll, Design 8
Two or more surfaces of an endodontically treated tooth does not require post retention
Class lll Class lll Amalgam is usually not indicated for anterior teeth due to Amalgam is usually not indicated for anterior teeth due to
its esthetic , but distal surface of the cuspid is a unique its esthetic , but distal surface of the cuspid is a unique location location
General principles are similar to class ll cavity preparation but with emphasis laid on in 5 areas of preparation1 esthetic concern2 extension for access3 stress consideration enamel rod directionIncisal access
Designs of cavity preparation at the distal slope of Designs of cavity preparation at the distal slope of the cuspidthe cuspid
Indications; 1 The lesion does not involve or undermine the distal slope of cupid2 bulky walls will remain, incisally, after removal of Undermine tissues3 the labials axial angle is intact4 the restoration will be directly loaded by vertical forces
Internal anatomy ;
Axial convex Depth - .5 from DEJ
Retention points : Depth 1 to 2 mm in dentin
Class lVClass lV
Indications :•Incisal angle is undermined •Labial and lingual walls intact
Labio lingual cross section
ModificationsModifications
Class V cavityClass V cavity Involvement :smooth surfaces apical to height of contour Involvement :smooth surfaces apical to height of contour on facial and lingual surfaces of all teeth eg ; erosion, on facial and lingual surfaces of all teeth eg ; erosion,
abrasion , hypoplasia, aplasiaabrasion , 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
•lesion are confined to lesion are confined to gingival third of the gingival third of the facisal or lingual third facisal or lingual third of the facial or lingual of the facial or lingual surfacesurface - axial angles intact - axial angles intact- no furcation - no furcation involvementinvolvement
Class V design 1
Class V ,design 2Class 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 shapeMesiodistal cross section
Mesio distal
Occluso gingival
Class V Design 3Class 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
Class V Design 4Class V Design 4
Multiple lesions in gingival third with sound tooth structure separating them
General shape
Class V Design 5Class V Design 5
Internal anatomy
Involves bifurcation or part of it
Class VIClass VI
Retention coves
Retention locks
Tooth preparation for pin Tooth preparation for pin amalgamamalgam
Pin location
Recent concept of cavity designs Recent concept of cavity designs v/s old design v/s old design
Black concept :Extension for prevention :Outline form – the cause of the problemThe logical alternatives :Outdated class l cavity design ;
Dental update 1985 360-370
Traditional occlusalTraditional occlusal
Narrow occlusal outline maintains the Narrow occlusal outline maintains the occlusal tooth structureocclusal tooth structure
Modern Class l Cavity design Modern Class l Cavity design
Occlusal surface
Cavosurface angleCavosurface angle
Drawback’s of black’s cavity designDrawback’s of black’s cavity design1. 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
•Conservative design (small is beautiful )•Tooth fracture :
Enamel –amalgam junctionEnamel –amalgam junction
Outdated class ll cavity designOutdated class ll cavity designocclusal shapeocclusal shapeis a wide isthmus necessary ?is a wide isthmus necessary ?
Retention grooves Gingival floors
Evolution of theMinimal class ll Amalgam cavityPreparation
Modern Class ll cavityModern Class ll cavity
operative dentistry vol 29,525-529
O
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!
ReferencesReferences 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