Page 59 - My FlipBook

The gingival wail should be flat and should form a right angle
with the pulpal wall. The buccal and lingual walls should diverge
toward the approximal and occlusal margins (Fig. 56). The walls
should be grooved in the dentin occluso-gingivally to form mortices
(Fig. 57), and they should run at right angles with the approximal
surface.
The gingival wall should be flat and should form
a right angle with the pulpal wall. The buccal and
Jlpproximo-Occlusal
Cavities with lingual walls should be so prepared that their mar-
a Step. gins extend in straight lines which slightly diverge
toward the occlusal surface (Fig. 58). These walls

Fig. 60.
should converge slightly toward the pulpal wall and they should unite
with this wall in the form of a curve.
The step should be deep enough to insure strength to the porce-
lain, and if possible it should be wide enough to form its margins at
points where there is no masticatory stress. Its seat should be flat
and at right angles with the pulpal wall. Its axial walls should diverge
toward the approximal marginal ridge (Fig. 58A), and also toward the
occlusal surface.
In extensive cases the buccal and lingual cusps
should be involved and the cavity margins extended
Carge
TTpproximoOcclusal on the buccal surfaces, obliterating to a large de-
eaoities. gree frail margins of porcelain on the occlusal sur-
face. The gingival wall should be flat and at right
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