Page 285 - My FlipBook

SIMPLE CAVITIES ON EXPOSED SURFACES. 283

eral way. Mats of foil may be substituted for tape, and where the decay
has progressed to such an extent as to involve a large portion of the
occlusal surface, making, as is frequently found, large round and quite
deep cavities, the gold may be introduced in the form of cylinders.
In former times, when the dentist's only means of excluding moisture
Fio. 235. Fig. 236. Fig. 237.

Fillings in molar fissure cavities.

was the napkin, and when his ability to keep cavities free from saliva
was for a limited time only, the use of cylinders was much more com-
mon than at the present time when the rubber dam is generally em-
ployed.
Cylinders for such cavities should be hand-made and of No. 4 non-
cohesive foil (Fig. 238). They should be long enough to extend above
the margins of the cavity as shown in Fig. 238 and arranged
Fig. 238.
around its walls. The first one is usually carried to that
point in the cavity farthest away, and should be pressed with
a foot-shaped instrument against the wall. Others are then
})ut in place and wedged laterally until room is made in the
centre of the mass for another cylinder, this in turn being
wedged toward the outer walls, and the operation continued
until no more cylinders can be introduced. The cylinders
Occlusal cav-
ity with cyl- should then be condensed with great force upon their pro-
inders.
truding ends, and finished with cohesive foil in the same
manner as previously described. This mode of filling is best suited to
deep cavities in which the walls are nearly parallel and yet sufficiently
strong to endure great lateral pressure.
In a cavity of unequal depth, where the central portion is quite deep
and the sulci radiating from it quite shallow (see Fig. 239), it is well to
use semi-cohesive foil in the central portion and cohesive
Fig. 239.
foil in the radiating sulci. Such fillings require to be well
anchored at the extremities of the fissures lest they be dis-
lodged by sticky candy, which often adheres with great
tenacity to the surface of the gold. The operator will do
Filled stellate
cavity in well in filling such cavities to confine himself to gold that
lower first
is quite cohesive, except in the central portion as above
molar.
indicated.
Class B.—Cavities situated uj^on the buccal surfaces of the bicus-
pids and molars are rather more difficult to fill because of the difficulty
in getting the rubber dam beyond the cervical border of the cavity.