Page 112 - My FlipBook

lOO MECHANICAL DENTISTRY AND METALLURGY.

for five minutes in a solution of chlorid of soda or common
salt and water to rcmoxe all traces of the acid.
The Finishing Process.—Superfluous portions of solder
are now to be removed, which may be more quickly accom-
plished by the use of burs, stones, and discs of various forms
and sizes attached to the dental engine. The final polish
may then be given l^y the use, first of crocus and then rouge
applied upon a French felt wheel, rapidly revolved upon the
lathe.

ARTIFICIAL DENTURES UPON A CAST
METAL BASE.

The method of constructing artificial dentures upon a
cast metal base has, until recently, had but a very limited
application.
The method, as commonly practiced, is chiefly applied to
lower dentures in cases where unusual absorption of the
alveolar ridge has taken place, recjuiring increased weight
to secure sufficient stability of the substitute. The alloys
employed for this work are those originally compounded by
Drs. Wood, Watt, and Weston, and are known upon the
market by these respective names—as Wood's, Watt's, or
Weston's Metal.
The manipulations concerned in this method are precisely
the same as for rubber work up to the flasking process,
except in forming the cast. As plaster-of-Paris alone will
not give sufficient strength, either to the model or to the
investment, it should in all cases be thoroughly mixed with
an ecj[ual part of either marble-dust, silex, pumice-stone, or
some other substance which will maintain its form perfectly 1
under the heat necessarily applied in thorough drying and in
casting the base.
Flasking.—Assuming that the teeth have been pro])erly