Transcript Cavity preparation according G.V.Black

Cavity preparation
according G.V.Black
II. Black class
3.Year - FS
G.V. Black’s Approach to
Cavity 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 to
Cavity Preparation
1. Outline 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 to
Cavity Preparation
2. 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 to
Cavity Preparation
3. 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 to
Cavity Preparation
4. 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 to
Cavity Preparation
5. 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 to
Cavity Preparation
6. 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 to
Cavity Preparation
7. Clean the cavity preparation

Rinse away all debris and dry the cavity
preparation.
Black class II. preparation
Black class II. preparation
Features of the Class II preparation:



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open gingival, lingual, buccal contacts;
dove tail; reverse “S”; convergent walls;
even depth;
smooth surfaces;
no sharp angles.
STANDARD PRINCIPLES
Margins 90° (perpendicular) to tangent to
carvosurface
 Proper clearance: 0.25mm – 0.5mm
 Occlusal, axial and gingival walls in dentin

Extension
Provide vertical support for occlusal forces

Avoid inclined planes
Provide vertical support for occlusal forces

Convert inclined planes to “steps”
Preparation
Incorporate the reverse-S curve (all walls
approx. 90 degrees to cavosurface)
Black II - MOD
Preparation
Proximal box and
rounded axiopulpal angle
Preparation
Just open” buccal proximal
wall
Black II - contact point
Positive contact
Matrix retainer
Matrix system
A matrix system provides and takes the place
of the proximal tooth surface that was removed
to restore the proximal contours and contact to
their normal shape and function.
Posterior Matrix System

Universal retainer
 Also referred to as the Tofflemire retainer. This
device holds the matrix band in position. The
retainer is positioned most commonly from the
buccal surface of the tooth being restored.
Components of a Universal Retainer
Posterior Matrix System

Matrix bands
 Matrix bands are made of flexible stainless steel
and are available in premolar, molar, and universal
sizes and thicknesses.
 The larger circumference of the band is the
occlusal edge and is always placed toward the
occlusal surface.
smaller circumference of the band is the
gingival edge and it is always placed toward
 The
the gingiva.
Wedges

A wedge is either triangular or round and
made of wood or plastic.

The wedge is inserted into the lingual
embrasure to position the matrix band firmly
against the gingival margin of the
preparation.
A wedge correctly positioned.
Sectional Matrices

A thin polished palodent-type band and a
tension ring produce a tight anatomic contact
for composite resin materials for class II
restorations.
Sectional matrices.
Thank you for attention!