rmly, _American Journal of Dental Science_, 1839.)

"An interesting debate here sprung up on the action where two metals are
used in one filling, such as gold and tin, the saliva acting as a
medium, and where the baser metal is oxidized by exhalents and by
imbibition through the bony tooth-structure." (Pennsylvania Society of
Dental Surgeons, 1848.)

"A patient came to me and complained of pain in the teeth. Upon
examination I found an amalgam filling next to one of tin. With a file I
made a V-shaped separation, when they experienced immediate relief from
pain." (Dr. Nevill, _American Journal of Dental Science_, 1867.)

In regard to the decay of teeth being dependent on galvanic action
present in the mouth, Dr. Chase, in 1880, claimed that a tooth filled
with gold would necessarily become carious again at the margin of the
cavity, wherever the acid secretions constantly bathe the filling and
tooth-substance. A tooth filled with amalgam succumbs to this
electro-chemical process less rapidly, while one filled with tin still
longer escapes destruction. The comparative rapidity with which teeth
filled with gold, amalgam, or tin, are destroyed is expressed by the
numbers 100, 67, 50. He prepared pieces of ivory of equal shape and
size, bored a hole in each, and filled them. After they had been exposed
to the action of an acid for one week, they had decreased in
weight,--viz, piece filled with gold, 0.06; amalgam, 0.04; tin, 0.03.

"With tin and gold, some have the superstition that the electricity
attendant upon such a filling will in some way be injurious to the
tooth; it matters not which is on the outside, when rolled and used as
non-cohesive cylinders each appears. We say that neither experimentally,
theoretically, nor practically can any good or bad result be expected
from the electrical action of a tin-gold filling on tooth-bone, and
neither will the pulp be disturbed." (Dr. W. D. Miller, _Independent
Practitioner_, August, 1884.)

"When the bottom of a cavity is filled with tin which is tightly
(completely) covered with gold, there is _practically_ no galvanic
action and there is no current generated by contact of tin and
gold,--_i.e._, no current leaves the filling to affect the dentin. That
portion of tin which forms the base is more positive than a full tin
filling would be. The effect is to cause the surface exposed to dentin
to oxidize more than tin would do alone; in that there is a benefit. In
very porous