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282 THE OPERATION OF FILLING CAVITIES.

strictly speakinfj, mallets, for the instriinu'iit is pushcfl rather than
driven forward l)y an eeeentrie. Tlie ]iiiekingham and the Holmes
mallets belong to this class. They have not the same steadiness of
motion as the ones previonsly described, and for this reason, among
others, have not been in general nse.
In the selection of jjluyger points for })ower mallets the operator will
do well to confine himself to those having more than one row of serra-
tions and those which are smooth-faced. The serrations, if any, should
be extremely shallow, and the corners of the instrument slightly
rounded. Those of the foot-shaped variety are admirably adapted to
power mallets, and as there is a great variety of patterns and sizes he
will have little difficulty in meeting his every wish in this particular.
A few points selected from the Webb, the Varney, and the Chappell
sets will fill all requirements. The accompanying cut (Fig. 233) shows
a ffood working set which has been selected from the three mentioned.

—
Filling by Classes.
(As arranged in Chapter VIII.)
I. Simple Cavities on Exposed Surfaces.
Bicuspids and Molars.
Class A.—The small cavities upon the occluscd surfaces of the
bicuspids and molars are among the simplest in form. They are shown
in Chapter VIII., Fig. 173. Cavities of this kind are quickly filled
by means of non-cohesive foil in the form of tape as shown in Fig.
222. Such cavities are usually of regular shape and of a form re-
quiring little if any additional shaping to make them retentive. A
length of tape varying from an inch to two inches should be taken
upon a wedge-shaped plugger point and carried to the bottom of
the cavity, ^vhere it may be held for an instant with a point in the
left hand ; the instrument in the right hand makes a fold of the gold
and carries it into and against the Avails of the cavity by a lateral mo-
tion ; fold after fold is then carried into the cavity and pressed firmly
in every direction. As it is alwavs best to finish such fill-
''
"Fif 234
ings with cohesive gold, a strip of No. 20 cohesive foil
should be wedged into the mass already in the cavity, and
then all subsequent pieces malleted, to give the occlusal
surface as great hardness as possible. A completed filling
of this class is shown in Fig. 234. Perfect adaptation to
the walls of the cavity is obtained by the use of the non-
cohesive foil, and great solidity is only essential upon the surface.
Cavities of this character, though of greater size, are found in the
molars, as shown in Figs. 235-237, and may be filled in the same gen-