Page 87 - My FlipBook

MATERIALS FOR FILLING. 83 ;

the anterior teeth. It is a less perfect conductor of
heat than gold ; on which account it is frequently em-
ployed where the latter metal can not be. It should
not be used in a tooth in which there is another metal

notwithstanding some economical dentists do some-
times use it to fill the interior of large cavities, placing
upon it a covering of gold. This method is objection-
able in two particulars : first, the tin is softer than
the gold, and under much pressure yields beneath it,
so as to destroy the integrity of the filling ; and second,
when the fluids of the mouth come in contact with
the two metals, a chemical action is induced, by which

the tin is rapidly corroded. It is for this reason that no
two metals should be applied to the same tooth ; as, for
instance, tin for filling a tooth round which there is
a gold clasp, or in contact with which is a gold plate.
Finally, the use of this material should be deter-
mined not only by all these circumstances, but also
by the constitutional predisposition of the patient,
and the character of the teeth, which should be dense

and well organized, in order to render it at all ad-
missible.
Silver.—This metal was formerly in more exten-
sive use as a material for filling, than it is at present.
It is not for this purpose superior to tin in any par-
ticular, except in being somewhat harder; and in
some particulars it is inferior, being quite as do-