Page 181 - My FlipBook

BUCCAL CAVITIES.
167
enter the orifice, thus the borders at once as it is
quite shaping pressed
through into the dentine. The removal of all carious material, and
a slight internal enlargement, will suffice where amalgam is to be used.
For gold, I should make slight extensions obliquely in opposite direc-
tions ; this not so much as a retentive precaution as to facilitate filling,
so formed will be more than one
since the cavity readily managed
which is perfectly regular and round. There is a strong temptation
here to wedge in a few large pellets, burnish, and call the tooth filled.
The true method is to use small pieces here as elsewhere. I should
choose for all such cases, except where the of the
gold youth patient
might make it advisable not to impose a lengthy operation ; then use
amalgam, explaining that gold will be inserted later in life.
Where the sulcus is well marked it should be cut out, the cavity
being extended toward, but not necessarily into, the-crown. This will
an The retentive formation in such cases
produce oblong filling.
would be an extension toward the gingival end of the cavity and
lateral, but slight undercutting, effected with a wheel bur. There
should be no undercut toward the crown, lest by weakening that
FIG. 194. FIG. 195.

point fracture result under the forces of mastication. Larger cavities
may be met, of all conceivable shapes. There may be two, or even
more, distinct cavities in the buccal surface of a single tooth, and in
each instance the operator will be called upon to connect them or fill
each as his judgment shall dictate. The main fact will
separately,
will be better retained
be to determine whether the fillings separately,
a Three cavities
or in one cavity. Fig. 194 presents good study.
are seen in the buccal surface of a molar. The smaller one, a, is in
the sulcus, and quite near it is another, 6, extending along the gum-
border. At c is a third, which almost encroaches upon the approxi-
mal surface, being near the angle^ Here it is plain that if in cavity a
my instruction to make a retaining extension at the gingival end were
b. True, the smaller
obeyed, the drill would emerge within the cavity
cavity could be filled, depending alone upon lateral undercutting ; but
when cavity b is similarly prepared it would be found that the separa-
tion between the two would be extremely frail. Here, then, it would
be best to unite and fill the two as a single cavity. Cavity c, however,
sound territory to permit of filling it
is distant, and in sufficiently
separately. Fig. 195 shows the tooth prepared for filling. The dotted