Class 1
Class 1
Class 1
General principles of
cavity preparation
I- Biological
II- Mechanical
The basic principles of tooth
preparation are as follows:
1. Initial tooth preparation:
• Outline form
• Primary resistance form
• Primary retention form
• Convenience form
2. Final tooth preparation:
• Management of remaining caries
• Secondary resistance and retention form
• Pulp protection, if required
• Finishing of enamel margins
• Final inspection of the preparation
Outline Form
The outline form means extending the preparation
margins to the place they will occupy in the final
preparation.
Following facts, must be kept in mind while making
outline form:
• Removal of all carious and defective pits and fissures .
• The out line form should be include all its pits and
fissures to avoid the caries recurrence ( extension for
prevention)
• Removal of all unsupported enamel rods
• To avoid ending preparation margins in high stress
areas like cusp tip and crest of the ridges.
• Placing margins on sound tooth structure.
Convenience Form
.
The convenience form of the preparation
facilitates and provides sufficient visibility,
accessibility and ease of operation in
preparation and restoration of the tooth.
Composite restoration
Cast metal
Gingival wall
Width of the wall about 1.5 – 2 mm
Axial wall
Parallel to long axis of the tooth at right angle
to the gingival wall
Convex ?
Meet the pulpal floor at axio-pulpal line angle
Axio- pulpal line angle should be round
Keep in mined that each part of
the compound class I cavity must
have its own retention and
resistance form - each part have
a separate means of resistance
and retention.