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176 FILLING TEETH.

flame of a spirit lamp to anneal it, and dispel all
foreign substances; it should in no case be brought
above a perceptible red heat; and usually not to that
point; it should be done carefully, so as not to fuse
any of the particles, as that would impair their facility
of cohesion in this process: small portions are often
required to fill up small interstices, or notches.
In crown cavities, the filling should begin at the
bottom; in proximal cavities, at the cervical wall.

By introducing the gold in this manner, the pressure
is made on a line with the axis of the tooth ; which
is an important consideration. The surface of the filling
should be made to conform to that of the lost portion of
the tooth; this can always be done except where the
tooth is largely broken away, and even then very
much may be accomplished, in many cases, to restore
the lost form; that will depend, however, upon the

method of using the gold. In crown fillings of the
molars and bicuspids, the antagonism of the teeth
must be regarded ; they should be formed for the
reception of the cusps of the opposing tooth. Proxi-
mal fillings should usually be convex; yet many good
fillings of this class are effected with a surface per-
fectly plain with the borders of the cavity. The
borders of the filling, however, are better protected
when it is somewhat convex.
Crystal gold, of perfect character, presents to the