Page 282 - My FlipBook

280 THE OPERATTON OF FILLJNfi CAVITIES.

better for j);if'kini»; cohesive
gold. I'lie best results arc
Fio. 232.
obtained by its use when the
gold is prepared in thin lani- Engink Mallet.
ina; or where a single thick-
ness of heavy foil or rolled
gold is employed.
Considerable experience is necessary to
enable the o])erator to use this instrument
with satisfaction to himself and his patient.
If the plugger point be pressed hard against "^'
the filling, the blows, which are delivered with
great rapidity and force, become painful and dis-
tressing and there is also danger of chipping the
cavity walls. The better plan is to hold the point ®
slightly away from the surface of the filling and
allow the mouKMitum which is given the instru-
ment by the falling armature to complete the
union of the various pieces of gold.
The ENGINE MALLET (sec Fig. 232) is intended
for use upon the dental engine. It is made with
a slip joint and can be applied in place of the
hand-piece to nearly all of the dental engines in
use, although it is best adapted to one of the
" cord " engines because of the greater freedom
of action. The instrument shown in the illus-
tration embodies many improvements in con-
struction which have been suggested by various
operators since the " Bonwill mechanical mallet,"
on which it is based, was introduced, and a jioint
of relative perfection has been reached where are
combined great efficiency with compactness and
lightness in handling. It will be seen by the
illustration that the essential feature of this in-
strument is a revolving wheel having inserted in
its periphery a hollow cylindrical steel roller.
This constitutes the hammer. It gives a " spring,"
not a "dead" blow, as it is held to its position by
a stiff steel spring. The roller revolves slightly
in its socket at each contact with the plimger.
When the engine is run at ordinary speed the
small wheel revolv^es with great velocity, deliver-
ing upon the head of the plunger as many as fif-