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102 OPERATIVE DENTISTRY

tact with these walls. The cast mlay will then not touch these
Avails during the process of introduction, which will often save a
fracture of these walls, due to stress from within when driving the
inlay home to a seat.
The Major Portion of Retention Form comes in for considera-
tion after the inlay has been cast and fitted and just before ce-
menting to place.- However, a flat seat and nearly parallel walls

I"'ig. 57.— Class One inlay in position showing gold wire cast in the filling, which was put
into the wax pattern to support the long buccal arm. Cavity shown at (B) Fig. 56.
to this seat Avith fairly definite angles, is necessary to guard against
the tipping strain and produce proper retention form.
Preparation of Cavities of Class Two.

Large proximal cavities in molars and biscupids are successfully
handled with this method of filling.
Access. Preliminary separation is of the greatest service here
and should be general practice as much cutting for convenience
form is avoided, and better contact secured.
Complete Preliminary Separation very materially facilitates the
removal of the wax pattern as the operator does not have to be
as careful about having his wax pattern tight against the surface
of the adjacent tooth. In addition to the preliminary separation
before making the pattern, it is to the advantage of the operator