Page 128 - My FlipBook

1 1 2 THE TREATMENT OF TEETH
discard its use in an approximal cavity, unless it
was completely covered up with gold.
Many dentists who have used tin, deny that it
rots, and the only means of reconciling these opposed
statements, is to suppose that the tinfoil supplied to
dentists is not always pure. It is well known that
much of the ordinary tinfoil of commerce is lead
coated with tin.
A reference to Taft's " Operative Dentistry," (p. 83,
4th edition) will show that the writer's experi-
ence with tin is not unique. Tin is useful for
flooring deep occlusal cavities that are to be filled
with gold, and a base for cohesive gold can often be
made more easily and quickly with tin, than with
non- cohesive gold in occlusal cavities. It would
also be extremely useful for starting gold fillings in
posterior cavities in bicuspids and molars, if its
maintenance of integrity could be relied on. When
used in contact with gold its exposed surface
becomes perfectly black, and it is therefore out of
place whenever this part of the filling is exposed to
view. Its use in incisors and cuspids is also gener-
ally contra-indicated, for even if completely covered
up with gold, it gives a dark, leaden appearance to
a labial wall. Whenever a cavity is floored with
tin, or whenever it is used for starting a filling, it is
a great convenience to be able to attach the gold to