Cavity preparation Cavity preparation according G.V.Blackaccording G.V.Black

II. Black classII. Black class

3.Year - FS

G.V. Black’s Approach toCavity Preparation

1. Outline form

2. Resistance form

3. Retention form

4. Convenience form

5. Removal of remaining caries

6. Finish enamel walls

7. Clean cavity preparation

G.V. Black’s Approach toCavity Preparation

1. Outline formOutline form

Based primarily on the location and extent of the caries.

Final outline form is not established until the carious dentin and, usually, its overlying enamel has been removed

G.V. Black’s Approach toCavity Preparation

2. Resistance form2. Resistance form

Resistance to both fracture of the tooth and filling material must be built in so both will be resistant to fracture during function

G.V. Black’s Approach toCavity Preparation

3. Retention form3. Retention form

The tooth preparation must be shaped in such a

way to retain the filling material, without

weakening the remaining tooth structure

G.V. Black’s Approach toCavity Preparation

4. Convenience form4. Convenience form

Allows adequate observation, accessibility, and ease of operation during the preparation and restoration of the tooth.

Only the minimal amount of reduction that will provide the necessary convenience should be done

G.V. Black’s Approach toCavity Preparation

5. Removal of the remaining caries5. Removal of the remaining caries

Deeper caries not removed by the initial cavity

preparation is now removed. Care must be

exercised as the pulp may be in close proximity.

G.V. Black’s Approach toCavity Preparation

6. Finish of enamel walls and margins6. Finish of enamel walls and margins

Remove unsupported enamel, make the margins

smooth and continuous to facilitate finishing of

the restoration.

G.V. Black’s Approach toCavity Preparation

7. Clean the cavity preparation7. Clean the cavity preparation

Rinse away all debris and dry the cavity

preparation.

Black class II. preparationBlack class II. preparation

Black class II. preparationBlack class II. preparation

Features of the Class II preparation:

open gingival, lingual, buccal contacts; dove tail; reverse “S”; convergent walls; even depth; smooth surfaces; no sharp angles.

STANDARD PRINCIPLESSTANDARD PRINCIPLES

Margins 90° (perpendicular) to tangent to Margins 90° (perpendicular) to tangent to carvosurfacecarvosurface

Proper clearance: 0.25mm – 0.5mmProper clearance: 0.25mm – 0.5mm Occlusal, axial and gingival walls in dentinOcclusal, axial and gingival walls in dentin

ExtensionExtension

Provide vertical support for occlusal forcesProvide vertical support for occlusal forces

Avoid inclined planesAvoid inclined planes

Provide vertical support for occlusal forcesProvide vertical support for occlusal forces

Convert inclined planes to “steps”Convert inclined planes to “steps”

PreparationPreparation

Incorporate the reverse-S curve (all walls approx. 90 degrees to cavosurface)

Black II - MOD

PreparationPreparation

Proximal box and rounded axiopulpal angle

PreparationPreparation

Just open” buccal proximal wall

Black II - contact pointBlack II - contact point

Positive contact

Matrix retainerMatrix retainer

Matrix systemMatrix system

AA matrix systemmatrix system provides and takes the provides and takes the place of the proximal tooth surface that place of the proximal tooth surface that was removed to restore the proximal was removed to restore the proximal contours and contact to their normal contours and contact to their normal shape and function.shape and function.

Posterior Matrix SystemPosterior Matrix System

Universal retainerUniversal retainer Also referred to as the Also referred to as the Tofflemire retainerTofflemire retainer. .

This device holds the matrix band in This device holds the matrix band in position. The retainer is positioned most position. The retainer is positioned most commonly from the buccal surface of the commonly from the buccal surface of the tooth being restored. tooth being restored.

Components of a Universal RetainerComponents of a Universal Retainer

Posterior Matrix SystemPosterior Matrix System Matrix bandsMatrix bands

Matrix bands are made of flexible stainless Matrix bands are made of flexible stainless steel and are available in premolar, molar, steel and are available in premolar, molar, and universal sizes and thicknesses.and universal sizes and thicknesses. The The largerlarger circumference of the band is circumference of the band is

the the occlusal edgeocclusal edge and is always placed and is always placed toward the occlusal surface.toward the occlusal surface.

The The smallersmaller circumference of the band is circumference of the band is the the gingival edgegingival edge and it is always placed and it is always placed toward the gingiva.toward the gingiva.

WedgesWedges

A A wedgewedge is either triangular or round is either triangular or round and made of wood or plastic. and made of wood or plastic.

The wedge is inserted into the lingual The wedge is inserted into the lingual embrasure to position the matrix band embrasure to position the matrix band firmly against the gingival margin of the firmly against the gingival margin of the preparation.preparation.

A wedge correctly positioned.A wedge correctly positioned.

Sectional MatricesSectional Matrices

A thin polished A thin polished palodentpalodent-type band -type band and a tension ring produce a tight and a tension ring produce a tight anatomic contact for composite resin anatomic contact for composite resin materials for class II restorations.materials for class II restorations.

Sectional matrices.Sectional matrices.

Thank you for attention!Thank you for attention!