Page 19 - My FlipBook

MATERIALS EMPLOVKD IN TAKING IMPRESSIONS. 7

This material has of late }'eai"s largely superseded the
use of beeswax for iiiii)ressions, on account of its taking
a somewhat sharper impression and Ijeing more elastic. It
has also many more desirable properties than gutta-percha,
which was formerly used extensively, but is now employed
to such a limited extent that it will not be considered in
this work.
The slightly elastic properties of modeling composition
makes it more suitable for impressions where there are
any overhanging ridges, bell-shaped teeth, or dove-tailed
interdental spaces.
Both modeling' composition and beeswax may be pre-
pared for use by softening with either dry heat or immers-
ing in hot water. Before removing an impression in
either of these materials from the mouth, it should be
cooled somewhat to preserve the form unchanged.
Beeswax.—Beeswax is a solid, concrete animal product,
prepared by the honey bees, and is extracted from the comb
after the honey has been removed. There are two varieties
of this^wax in common use, the white and yellow. When
first obtained from the comb it is of a bright yellow color,
and in order to bleach it and obtain what is knowai as white
wax it is reduced to thin cakes exposed for a long time to
the sun in the open air ; this renders it less tenacious, but
it is preferred by some on account of its color.
Moldine.—Moldine is a plastic material devised partic-
ularly to secure the impression of a single tooth, either
in or out of the mouth, for the purpose of securing a metal
die of the same. It is composed of potter's clay mixed
with glycerin to the consistency of stiff putty. With this
material the operator is enabled to quickly secure a metallic
die of a tooth directly from the impression.