Page 141 - My FlipBook

OPENING. 1ST

projections of enamel : it is very difficult, and in
many cases impossible, to fill perfectly beneath such
portions ; and again, they are liable to be broken
down during mastication.
For opening up these cavities, in many cases the
bur drill alone will be quite sufficient ; those of dif-
ferent sizes being employed, to open up the orifice
gradually, so that too much violence may not be clone
to the teeth. In all very small cavities, the bur is

all that is required, except in decayed fissures.
In cases where the decay is more extensive, and
the cavity larger, the chisel or heavy cutting instru-
ment, in connection with the drill, will be found very
useful. Fig. 41 represents valuable forms of these
instruments.

Fig. 41.

An instrument first brought to the notice of the
profession by Dr. I. Forbes, is very valuable for open-
ing and enlarging crown cavities of the molars. It
consists of a socket-handle, which receives a screw-
clamp, and this receives the bits; which arc o^