Class II � SMOOTH surface lesions

� Occur on PROXIMAL SURFACES

of MOLARS & PREMOLARSof MOLARS & PREMOLARS

Spread of smooth surface caries Spread of smooth surface caries Spread of smooth surface caries Spread of smooth surface caries in enamel & dentinin enamel & dentinin enamel & dentinin enamel & dentin

In EnamelCone shape

Base towards outer E surface

& apex toward DEJ& apex toward DEJ

In Dentin Cone shape

Base towards DEJ

& apex towards the pulp

How to diagnose ??• Tactile ………………by mirror & probe a

curved probe is indicated

*lesion my appear chalky white

*Marginal ridge may be discolored*Marginal ridge may be discolored

• Radiographic………….bite wing radiographs

It could be

• Simple only Mesial (M) or Distal (D)

• compound ………..two surfaces• compound ………..two surfaces

Mesio-occlusal (MO) or Disto-occlusal (DO)

• Complex ……more than ) surfaces

Mesial-occlusal- Distal (MOD)

Simple class II

• Prepared Only when there is direct

access to the proximal surface such as:

- an isolated tooth

- wide interproximal embrasure

• Trapezoidal in shape with

occlusal,gingival,buccal &lingualwalls

located in the embrasures

But this is not always possible to do a simple class II

So

The proximal surface is ACCESSED The proximal surface is ACCESSED

through the occlusal surface

Compound or Complex Compound or Complex Compound or Complex Compound or Complex

Extension for convenience Extension for convenience Extension for convenience Extension for convenience

CAVITY PREPARATIONS FOR CLASS II LESIONS

The usual form of a class II cavity

preparation comprises three parts:

++. . ++. . The occlusal portion

,. . The proximal portion

-. Connected together by an ISTHMUS

The occlusal part follows the same fundamentals as for class I• Depth ………………Depth ………………Depth ………………Depth ………………1111....5555 –––– 2222mm mm mm mm (0.5 mm in dentin)• Flat pulpal floorFlat pulpal floorFlat pulpal floorFlat pulpal floor• Flat pulpal floorFlat pulpal floorFlat pulpal floorFlat pulpal floor• Parallelism of adjacent wallsParallelism of adjacent wallsParallelism of adjacent wallsParallelism of adjacent walls• Undercuts ………………..Undercuts ………………..Undercuts ………………..Undercuts ………………..except that except that except that except that the external outline is extendedthe external outline is extendedthe external outline is extendedthe external outline is extendedproximally toward the defective proximal proximally toward the defective proximal proximally toward the defective proximal proximally toward the defective proximal surfacesurfacesurfacesurface

The outline form of the proximal box dependson several factors:i.i.i.i. Extent of caries: Extent of caries: Extent of caries: Extent of caries: more extensioni.i.i.i. Extent of caries: Extent of caries: Extent of caries: Extent of caries:

mostly caries are around the contact areaii.ii.ii.ii. Convexity of the proximal surfacesConvexity of the proximal surfacesConvexity of the proximal surfacesConvexity of the proximal surfaces:

more convex smaller contact area less extension

iii.iii.iii.iii. Caries & plaque indicesCaries & plaque indicesCaries & plaque indicesCaries & plaque indices: indices iv.iv.iv.iv. Masticatory loadMasticatory loadMasticatory loadMasticatory load: load

more extension

minimal bucco-lingual width

Objectives for extension Objectives for extension Objectives for extension Objectives for extension of proximal marginsof proximal marginsof proximal marginsof proximal margins

• Include all caries , faults ,or existing Include all caries , faults ,or existing Include all caries , faults ,or existing Include all caries , faults ,or existing restorative materialrestorative materialrestorative materialrestorative material

• Create Create Create Create 90909090°°°° cavosurface margins cavosurface margins cavosurface margins cavosurface margins Create Create Create Create 90909090°°°° cavosurface margins cavosurface margins cavosurface margins cavosurface margins ( i.e. butt joint margins)( i.e. butt joint margins)( i.e. butt joint margins)( i.e. butt joint margins)

• Establish (ideally) not more than Establish (ideally) not more than Establish (ideally) not more than Establish (ideally) not more than 0000....5555 mm mm mm mm clearance with the adjacent proximal surface clearance with the adjacent proximal surface clearance with the adjacent proximal surface clearance with the adjacent proximal surface facially, facially, facially, facially, linguallylinguallylinguallylingually, & , & , & , & gingivallygingivallygingivallygingivally

((((could be checked by the tip could be checked by the tip could be checked by the tip could be checked by the tip of a sharp explorer)of a sharp explorer)of a sharp explorer)of a sharp explorer)

The proximal outline is an INVERTED The proximal outline is an INVERTED The proximal outline is an INVERTED The proximal outline is an INVERTED TRUNCATED CONE withTRUNCATED CONE withTRUNCATED CONE withTRUNCATED CONE with

�GINGIVA L wall forming the base GINGIVA L wall forming the base GINGIVA L wall forming the base GINGIVA L wall forming the base &&&&

�FACIAL /BUCCAL and FACIAL /BUCCAL and FACIAL /BUCCAL and FACIAL /BUCCAL and �FACIAL /BUCCAL and FACIAL /BUCCAL and FACIAL /BUCCAL and FACIAL /BUCCAL and LINGUAL walls forming its sides LINGUAL walls forming its sides LINGUAL walls forming its sides LINGUAL walls forming its sides

Inverted truncated coneInverted truncated coneInverted truncated coneInverted truncated coneProximal box isProximal box isProximal box isProximal box is• WiderWiderWiderWider at the gingival area than the occlusal

i.e.i.e.i.e.i.e.i.e.i.e.i.e.i.e.• Buccal & lingual Buccal & lingual Buccal & lingual Buccal & lingual walls are converging occlusally following the outer contourfollowing the outer contourfollowing the outer contourfollowing the outer contourof the buccal & lingual surfaceof the buccal & lingual surfaceof the buccal & lingual surfaceof the buccal & lingual surface

INVERTED INVERTED INVERTED INVERTED TRUNCATED CONE TRUNCATED CONE TRUNCATED CONE TRUNCATED CONE

ContributesContributesContributesContributes RESISTANCE RESISTANCE RESISTANCE RESISTANCE & & & & RETENTIONRETENTIONRETENTIONRETENTION to the proximal boxto the proximal boxto the proximal boxto the proximal box

**** Buccal & lingual walls Buccal & lingual walls Buccal & lingual walls Buccal & lingual walls B &L proximal margins are extended :B &L proximal margins are extended :B &L proximal margins are extended :B &L proximal margins are extended :• To include cariesTo include cariesTo include cariesTo include caries

SOSOSOSO

• To include cariesTo include cariesTo include cariesTo include caries• Extended to Extended to Extended to Extended to B & L embrasures B & L embrasures B & L embrasures B & L embrasures To To To To break contact with the adjacent tooth break contact with the adjacent tooth break contact with the adjacent tooth break contact with the adjacent tooth ((((0000....3333----0000....5555mm)mm)mm)mm)

Tip of an explorer should pass through Tip of an explorer should pass through Tip of an explorer should pass through Tip of an explorer should pass through easilyeasilyeasilyeasily

(convenience)(convenience)(convenience)(convenience)

� located in the located in the located in the located in the GINGIVAL GINGIVAL GINGIVAL GINGIVAL EMBRASUREEMBRASUREEMBRASUREEMBRASURE just Below the just Below the just Below the just Below the

****GINGIVAL WALL (floor)GINGIVAL WALL (floor)GINGIVAL WALL (floor)GINGIVAL WALL (floor)

EMBRASUREEMBRASUREEMBRASUREEMBRASURE just Below the just Below the just Below the just Below the contact area (contact area (contact area (contact area (0000....5555----1111mm)mm)mm)mm)

�Formed of Formed of Formed of Formed of both enamel & dentin both enamel & dentin both enamel & dentin both enamel & dentin �Parallel to the occlusal surfaceParallel to the occlusal surfaceParallel to the occlusal surfaceParallel to the occlusal surface

�Width about Width about Width about Width about 0000....1111----1111....5555mm mm mm mm depending on the tooth to be depending on the tooth to be depending on the tooth to be depending on the tooth to be preparedpreparedpreparedprepared

•The gingival wall could extend to The gingival wall could extend to The gingival wall could extend to The gingival wall could extend to reach reach reach reach cementumcementumcementumcementum

so so so so

sometimessometimessometimessometimes

so so so so width of gingival wall will be less than width of gingival wall will be less than width of gingival wall will be less than width of gingival wall will be less than 1111mm (approximately mm (approximately mm (approximately mm (approximately 0000....7777----0000....8888mmmmmmmm))))

• Axial wall is parallel to the long axis of the Axial wall is parallel to the long axis of the Axial wall is parallel to the long axis of the Axial wall is parallel to the long axis of the tooth gingivotooth gingivotooth gingivotooth gingivo----occlusallyocclusallyocclusallyocclusallywith with with with slight slanting towards the pulpal floor slight slanting towards the pulpal floor slight slanting towards the pulpal floor slight slanting towards the pulpal floor iiii.e. tapered occlusally .e. tapered occlusally .e. tapered occlusally .e. tapered occlusally (forming an obtuse (forming an obtuse (forming an obtuse (forming an obtuse

****AXIAL WALLAXIAL WALLAXIAL WALLAXIAL WALL

with with with with slight slanting towards the pulpal floor slight slanting towards the pulpal floor slight slanting towards the pulpal floor slight slanting towards the pulpal floor iiii.e. tapered occlusally .e. tapered occlusally .e. tapered occlusally .e. tapered occlusally (forming an obtuse (forming an obtuse (forming an obtuse (forming an obtuse angle with the pulpal floor)……………why?????angle with the pulpal floor)……………why?????angle with the pulpal floor)……………why?????angle with the pulpal floor)……………why?????

To increase thickness of amalgam

At the isthmus portion ……..

& so increase resistance

• Placed into dentin Placed into dentin Placed into dentin Placed into dentin o.o.o.o.5555----o.o.o.o.8888 mm from DEJ mm from DEJ mm from DEJ mm from DEJ

The axial wall should The axial wall should The axial wall should The axial wall should parallel theparallel theparallel theparallel thefaciofaciofaciofacio----lingual lingual lingual lingual contourcontourcontourcontour

Connects the occlusal Connects the occlusal Connects the occlusal Connects the occlusal & proximal boxes& proximal boxes& proximal boxes& proximal boxes

• WidthWidthWidthWidth ……………………….……………………….……………………….……………………….narrow as possiblenarrow as possiblenarrow as possiblenarrow as possible• WidthWidthWidthWidth ……………………….……………………….……………………….……………………….narrow as possiblenarrow as possiblenarrow as possiblenarrow as possible----¼ intercuspal distance¼ intercuspal distance¼ intercuspal distance¼ intercuspal distance

((((1111----1111....5555mm wide)mm wide)mm wide)mm wide)

Resistance

The facial (buccal) & the lingual walls of the occlusal cavity at the ISTHMUS portion should approach the proximal portion should approach the proximal

surface at a right angle (butt joint)

Resistance

soThese walls may, therefore, be cut into:

1111. . . . a uniform curvea uniform curvea uniform curvea uniform curve2222. straight line. straight line. straight line. straight line3333. reverse "s. reverse "s. reverse "s. reverse "s----curve" (facially) curve" (facially) curve" (facially) curve" (facially) 3333. reverse "s. reverse "s. reverse "s. reverse "s----curve" (facially) curve" (facially) curve" (facially) curve" (facially)

Depending on:iiii.... the occlusal anatomy of the tooththe occlusal anatomy of the tooththe occlusal anatomy of the tooththe occlusal anatomy of the toothii.ii.ii.ii. the position and size of contact areathe position and size of contact areathe position and size of contact areathe position and size of contact areaiii. the width of the embrasuresiii. the width of the embrasuresiii. the width of the embrasuresiii. the width of the embrasures

Usually Usually Usually Usually The lingual embrasure is wider The lingual embrasure is wider The lingual embrasure is wider The lingual embrasure is wider than the buccal embrasure than the buccal embrasure than the buccal embrasure than the buccal embrasure

So in such casesSo in such casesSo in such casesSo in such casesThe extension of the bucco The extension of the bucco The extension of the bucco The extension of the bucco ––––The extension of the bucco The extension of the bucco The extension of the bucco The extension of the bucco ––––proximal wall into the embrasure proximal wall into the embrasure proximal wall into the embrasure proximal wall into the embrasure leads to excessive cutting of the leads to excessive cutting of the leads to excessive cutting of the leads to excessive cutting of the buccal cuspbuccal cuspbuccal cuspbuccal cusp

To avoid this To avoid this To avoid this To avoid this A A A A reverse curve reverse curve reverse curve reverse curve (S shape curve) (S shape curve) (S shape curve) (S shape curve) is is is is made in the made in the made in the made in the buccal proximal wall buccal proximal wall buccal proximal wall buccal proximal wall so as so as so as so as to :to :to :to :•Have a Have a Have a Have a butt joint butt joint butt joint butt joint with the cavosurface with the cavosurface with the cavosurface with the cavosurface marginmarginmarginmarginHave a Have a Have a Have a butt joint butt joint butt joint butt joint with the cavosurface with the cavosurface with the cavosurface with the cavosurface marginmarginmarginmargin•Have a Have a Have a Have a dentin supported dentin supported dentin supported dentin supported bucco bucco bucco bucco ––––proximal wallproximal wallproximal wallproximal wall

Resistance

Ideal extension

Each part of the cavity Each part of the cavity Each part of the cavity Each part of the cavity should have its own should have its own should have its own should have its own resistance and resistance and resistance and resistance and resistance and resistance and resistance and resistance and

retentive featuresretentive featuresretentive featuresretentive features(self dependent)(self dependent)(self dependent)(self dependent)

• Prepare occlusal box• Extension to the involved proximal surfacePrepare the axial wall uniformly Prepare the axial wall uniformly Prepare the axial wall uniformly Prepare the axial wall uniformly 0000....5555 mm in dentinmm in dentinmm in dentinmm in dentin

How to prepare ?? How to prepare ?? How to prepare ?? How to prepare ??

• Prepare the axial wall uniformly Prepare the axial wall uniformly Prepare the axial wall uniformly Prepare the axial wall uniformly 0000....5555 mm in dentinmm in dentinmm in dentinmm in dentin• Extend cavity buccal, lingual & gingivalExtend cavity buccal, lingual & gingivalExtend cavity buccal, lingual & gingivalExtend cavity buccal, lingual & gingival

Resistance and retention are Resistance and retention are Resistance and retention are Resistance and retention are achieved by…………..?????achieved by…………..?????achieved by…………..?????achieved by…………..?????

Resistance and retention are Resistance and retention are Resistance and retention are Resistance and retention are achieved by…………..?????achieved by…………..?????achieved by…………..?????achieved by…………..?????

Extra means of retention………..???Extra means of retention………..???

Finishing of enamel Finishing of enamel Finishing of enamel Finishing of enamel Finishing of enamel Finishing of enamel Finishing of enamel Finishing of enamel margins…………how.??????? margins…………how.??????? margins…………how.??????? margins…………how.???????

Finishing of enamel Finishing of enamel Finishing of enamel Finishing of enamel margins…………how.??????? margins…………how.??????? margins…………how.??????? margins…………how.???????

• A type of preparation which preserves as much tooth structure as possiblepossible

• Access is also gained through the marginal ridge of the affected mesial or distal surface & no further extension to the occlusal surface

•The buccal & lingual walls & meet the surface

of the tooth at to provide

bucccoaxially & lingoaxiallylingoaxially