Page 38 - My FlipBook

the pounds pressure exerted by the mallet, between the mal-
let and this board, for instance (demonstrating), not how far
the board is moved. This subject has been one of great
difficulty. In speaking to a portion of the class yesterday I
spoke of an article related to this subject, which I gave be-
fore the Nev/ York Odontological Society, pubHshed in
Cosmos, 1896, page 269. The portion upon filling materials
begins at page 302. In reading this article you will find that
1 have had men prominent in the profession make fillings in
matrices, using such force as they usually use in filling teeth,
and I have v^^eighed these, obtained their specific gravity and
found the differences in consoHdating gold among these dif-
ferent men. These differences are very wide indeed. I have
also had many fillings made by prominent operators, and
those not so prominent, in teeth—fillings that have been lost
from this cause or that—or the teeth have been extracted.
I obtained definite data as to the service they had rendered,
and have obtained the specific gravity of these and found
the differences in their density. And here again we find very
wide discrepancies, discrepancies that are much wider than

they should be. This is to be expected when we have no
means of accurately studying this subject, and without the
means of knowing what others are doing. Among those that
have been made in teeth in the mouth the heaviest filling
that I found was made by Dr. McKellops of St. Louis, in
which he built up two-thirds of the crown of a bicuspid tooth.
He obtained a dentisty, or a specific gravity, of 17.10. The
highest specific gravity that can be obtained in hammered

gold being 19.4. This is a pretty close approach to absolute
solidity, and yet was built upon a tooth with a comparatively
small root. It stood the test of wear for twenty years, when
the anchorage broke away and the filling was lost. Others
run down very low— 15, 14 and 13, some of them. FilHngs
that are of a lower specific gravity than 15 usually give away
very quickly; in fact, they absorb more or less. Take such
a filling, wash it clean with alcohol—one that has been worn
in the mouth—and then expose it to heat and you will see
very quickly by the fumes given off that filling has ab-
sorbed animal matter. The gold is not packed close enough
to make it Vs^ater-tight.
I have been for a number of years at work on this sub-

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