Page 385 - My FlipBook

THE PORCELAIN INLAY. 383
removed there will be no difficulty in teasing out an undistorted matrix
from the cavity.
The color of the filling must next be decided by means of a shade
ring. The basal color of nine-tenths of all porcelain fillings is light
yellow, and white added according to necessity will in a large number
of cases be all that is required to obtain a perfect match. Whatever tint
is desired, the basal color should be first ascertained, when the correct
toning material may be added with comparative ease. The thoroughly
mixed body, being wet with distilled water and dried \vith blotting-paper
to the consistence of dough, is placed in the matrix on the point of the
brush or spatula (Figs. 357 and 358), and settled to the bottom with a
few taps on the pliers that hold the platinum. The porcelain should not

Fig. 366.

Position of fingers : right lower bicuspid.
be allowed to come quite to the edge. After it has been carefully dried by
turning it face downward on a piece of soft muslin, the filling is placed
in an electric or gas furnace, as the case may be, and baked until a gloss
appears. It is then removed, cooled, and placed again accurately in the
cavity, and the edges once more burnished down.
This second burnishing is the most important part of the operation,
for however perfect the first adaptation may have been, the edges must
of necessity be warped in the furnace by the unequal expansion and
contraction of the porcelain and platinum. This contraction having for
the most part occurred, a second burnishing makes an adaptation that
may be practically perfect. The pai-tially filled matrix must then be
removed, filled up to the edges with porcelain paste, and finally baked.