Page 375 - My FlipBook

PORCELAIN COMPARED WITH OTHER MATERIALS. 373

this line of cement may be rendered so microscopic as to become prac-
tically no longer a source of danger. In other respects the gold inlav,
when not visible, approaches very nearly the requirements of the ideal
filling, having the advantages of perfect resistance to mastication, pre-
clusion from growth of bacteria, non-conductivity of variations in tem-
perature, easy manipulation, firm adherence to cavity walls, and an
adaptation not usually so expensive to tooth structure as is the ordinary
insertion of a gold filling.
We shall now speak of the porcelain inlay, which in labial and buccal
cavities fulfills more nearly than any other the characteristics of the ideal
filling. Such a filling may possess color that really matches the tooth.
It may be set with a cellulose cement that almost absolutely resists the
oral fluids. It excludes germs of decay and precludes from growth
those that enter. A porcelain inlay is a non-conductor of heat, it
adheres to cavity walls, its manipulation is easy to the patient, and is con-
servative of tooth structure. The only real objection to labial porcelain
fillings is in the fact that great skill and patience are required in their
insertion. Where, however, porcelain inlays have to withstand heavy
strain in mastication, as in Figs. 370, 375, and 376, they are liable to chip
on the edges, and thus to demand the use of oxyphosphate of zinc as a
cement. This objection, therefore, renders them somewhat less service-
able than gold inlays for non-visible approximal cavities in molars and
bicuspids. For while the porcelain is sufficiently strong to withstand
the crushing force of mastication, the chipping of the margin tends to
accentuate the weakness already found in the solubility of the cement,
which is its sole defence against bacteria. If such chipping occurs on
the masticating surface of the molars or bicuspids, the fractured mar-
gins can be readily filled with gold in such a way that edge strength
equal to gold is obtained. Also, if the edges of the inlays are painted
with insoluble cellulose^ before the filling is cemented into place, all the
strength and adhesibility of oxyphosphate of zinc can be combined.
Thus with care and patience the porcelain inlay acquires the advantages
of gold, cement, and porcelain, while it has none of the usual disad-
vantages. The porcelain filling properly guarded may have the natural
color possessed by no other filling material, strength to withstand masti-
cation, resistance to the fluids of the mouth, poAver to exclude bacteria
and to inhibit the growth of those that enter, non-conductivity of heat,
adaptation, and conservatism of tooth structure. And if at times the
manipulation for the dentist is of necessity so deft and artistic that the
highest skill and judgment are required, it is but further evidence that
the finest work is usually the most difficult.
^Tbe Doyle cement, a cellulose cement, is claimed to be permanent, and seems
promising, but only years of experience can prove its value.