Page 664 - My FlipBook

326 THE TECHNICAIi PBOCEDUEES IN FILLING TEETH.

made on either side of the widest part of the matrix, as shown
in Figure 414, b. These little pieces may then be raised and the
ligature placed under them, as shown in Figure 414, c, and it can
not slip occlusally.
I have tried all kinds of ready-prepared matrices, but have
found none of them so satisfactory as those prepared by the
operator for each case. ~\ATiatever form of matrix is used, it
should be secured very firmly in place to withstand hea\y pres-
sure on the amalgam.
Sepaeation. "VYlien the matrix has been placed, the Perry
separator should be applied over the matrix, or in many cases,
the matrix may be held with the separator without the ligature.
It is just as important to separate the teeth for amalgam fillings
as for gold fillings, and on no account should this be neglected
in proximal fillings where there is a proximating tooth. After
the desired separation has been secured, the matrix should be
formed to the shape that the proximal surface of the filling
should be when finished. Figure 417. If a soft matrix material
is used, it may be formed with a burnisher. If a stiff material,
such as steel, is used, it will not remain against the proximating
tooth if forced there, but will spring back. It may easily be
made to stay by using two instruments at the same time, forcing
the matrix against the i^roximating tooth with one, while pres-
sure is made first from the buccal and then from the lingual
with the other, forcing the buccal and lingual portions of the
occlusal edge of the matrix tightly against the buccal and lin-
gual surfaces of the tooth over which it is applied. After the
preparation is otherwise complete, a careful examination of the
gingival margin of the cavity should be made to see that the
matrix is close at that point, and if it is not, it should bo brought
close, by inserting a small, soft wood wedge from the lingual
side with just sufficient force to bring the matrix close. This
is most likely to be needed in molars that have broad, flat, prox-
imal surfaces.
Placing the filling. When everything is in readiness,
the alloy and mercury, which have been previously measured,
are mixed, kneaded and packed, as has been described. The
imjiortance of the best form of instrument for packing amalgam
can hardly be overestimated. Until I had examined this over
and over again, experimentally, under conditions which enabled
me to determine results, T had no idea of the importance of the
instrument forms for this purpose. The one thing needful in
packing amalgam is to grasp the mass as a whole as nearly