Page 688 - My FlipBook

346 THE TECHNICAL PROCEDURES IN FILLING TEETH.

with the ball of cotton repeated, pressing the platinum more and
more closely to the cavity walls at each annealing until the cav-
ity can be forced full of cotton over the matrix. Then the mar-
gins lying on the surface of the tooth should be smoothed down
to the surface of the tooth with a steel burnisher used lightly,
being careful to smooth out all tendency to the formation of
folds.
An examination will show that while generally the platinum
is fitted to the cavity walls, it has not been forced perfectly into
the angles. It should again be annealed and returned to the
cavity, and while held in position it should be gradually forced
into all angles with a smooth steel burnisher. Burnishers for
this work are provided by the dealers in a suitable variety of
forms. The burnishing may be facilitated by cutting a small
band from rubber dam and placing this over the tooth so as
to cover the matrix and hold it firmly in position. A small hole
should have been cut in this rubber and placed immediately over
the cavity to work through. This rubber will prevent any tip-
ping of the matrix while burnishing. When this is apparently
complete, reanneal and return the matrix to the cavity, and when
it is well settled into position, touch it at different points with the
point of the burnisher and look carefully for any springing or
tilting. If there is any, the part where this occurs is not perfectly
fitted and must be burnished down.
Before this burnishing is finally completed, that portion
overlapping the surface of the tooth should be trimmed fairly
close and yet left sufficiently long to show very plainly the cav-
ity margins and form of the surroimding surface; for this is
the guide to the fullness of the inlay. It is often well to leave
one convenient point a little long to facilitate handling with the
pliers. When the finished matrix is finally removed from the
cavity, it should be done with the greatest care not to bend it in
any of its parts. To this end, it should be very carefully teased
out until well loosened from its bed, when it may be carefully
lifted away with the pliers. The pliers for this purpose should
have a locking device, so that when once the matrix is taken up
it is permanently held. The matrix is now ready to receive the
porcelain body for baking.
There are a number of processes in which the impressions
of the cavities are taken and the inlays swedged over these as
models, or in which a reverse of the impression is made and the
inlay formed in that.
An impression of the cavity may be taken in modeling com-