Page 37 - My FlipBook

Occasional!}- a step may be used in simple ap-
proximal cavities. The labial outline of the cavity
Simple Hpproximal
Gapities with should have the same form as that previously de-
a Step. scribed. The gingival wall, however, should extend
from the labial wall through to the lingual surface,
and the pulpal wall should be prepared the same as in Fig. 15.
A step should be cut on the lingual surface extending through the
gingival and middle thirds of the tooth (Fig. 19). The lateral extent of
this step is determined by the degree of stress to which the tooth is sub-
ject. It should be as deep as the pulp will permit. The pulpal wall of
the step should form a right angle with the pulpal wall of the cavity.
Care should be exercised to prevent the step from extending too near the
incisal edge.
The enamel should be removed laterally from
the gingival to the incisal wall with a dentate fissure
tecbniauc of
Preparing the bur and small stones in the right angle. After this
Step. has been done, a fissure bur with face at a right
angle with its axis should be used to deepen the
cavity. Enough of the gingival should be involved to prevent frail
margins of porcelain in this region. The margins should be finished
with properly shaped plug-finishing burs or Arkansas stones. A slight
groove should extend along the angle of the pulpal and lateral wall of
the step in the gingivo-incisal direction (Fig. 19 A). The cavity should
be so prepared that the distance from the gingival to the incisal margin
on the lingual surface is greater than this distance on the labial surface
(Fig. 19 B).

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