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ARTIFICIAL DENTURES. 97

the teeth are then Irinuiied to the pr()i)er \\i(hh, and scal-
loped, if desired, in correspondence witli the festoons of the
artificial gums. In whatever way the rim is formed, wlien
it has been fitted to the plate and teeth it may he lield tem-
porarily in place with clamps adjusted at two or three
points around the plate and then transferred to a soldering
block, and secured by first tacking it at two or three points
with solder. The groove may then be filled with whiting,
mixed with water or alcohol, to prevent the solder from
flowing in and filling it up ; after which small pieces of
solder are placed along the line of union next to the edge of
the plate, and the rim permanently united throughout with
the blowpipe; following which the wax and teeth are reap-
plied to the plate.*
Investing.—The plate, with the wax and teeth in place,
is next invested preparatory to backing the teeth and uniting
them with solder to the base. For this purpose, plaster and
sand in equal parts may be employed. It is customary to
incase the piece in the plaster mixture to the depth of from
one-half to three-fourths of an inch, leaving only the lin-
gual surface of the plate and teeth uncovered.
Backing the Teeth.—The plate being properly invested,
all portions of the wax attached to the inner surface of the
teeth and plate should be thoroughly removed with suitable
instruments, after which backings are to be adjusted to the
teeth.
A plain strip, corresponding in width with the tooth to
be lined, is cut, and the end resting- on the main plate con-
formed accurately with the file to the irregularities on the
surface of the latter, and in such a manner as to permit the
strip to take the direction of the tooth. The general form

* For a fuller description, see Richardson's Mechanical Dentistry,
7th Edition.