Page 137 - My FlipBook

APPROXIMAL CAVITIES IN BICUSPIDS.
123
pressure, using a foot-plugger. Next I cover this with a piece of No.
60
gold and mallet it down, again using the foot instrument. By this
method the whole border is well and rapidly covered, the under pellet
serving as a soft cushion which easily adapts itself to irregularities
under the mallet-stroke, while the
heavy foil is stiff enough to hold all
in as it is condensed.
place
As with incisors, the
palato-approximal cavity is more difficult in a
bicuspid than the labio-approximal. I nlay therefore better choose
the latter for an illustration to show in what its management differs
from that advocated in the incisor
region. Fig.
131 shows a bicuspid having such a cavity. There FIG. 131.
might be circumstances under which I should use
a screw here, but when we remember that this
po-
sition is inaccessible, and that a screw renders any
case more is extreme
trying, it plain that only
would The main
necessity urge its adoption.
reliance here will be to resort once more to labio-
and palato-gingival extensions, as shown at a and
b. I should not make much of a groove under
the labial wall, but, passing from the extension, I
palato-gingival
should make a slight groove along the palatal border, deepening it
as I approached the crown, till at c it became a distinct concavity.
Whether caries has involved the crown or not, the sulcus must be cut
out across to its and at that a
opposite extremity, point deep retaining-
should be made as advocated and illustrated by Fig. 28, shown
pit
also less in the at d. In some instances, pos-
distinctly present figure
sibly because of extreme sensitiveness, or perhaps from the poor shape
of the tooth, only very slight retentive shape may be attainable along
the gingival part of the cavity. This would necessitate a proportion-
ate deepening of the palatal groove and the formation of a more
distinct one under the labial wall, care being taken not to so under-
mine it as to weaken it. I should call attention here to the fact that
these directions exactly contradict those given for the same cavities in
the incisors. There the groove, when made at all, was along the
wall left while in I direct that it shall be made
standing, bicuspids
along that side where the greatest loss has occurred. The latter prin-
is the more correct, but it is in the incisor, for there,
ciple inapplicable
there will not be found sufficient space in which to make a groove,
which, if it escape the pulp, will not leave the enamel which it under-
mines so weak that it adds nothing to the strength of the cavity. In
the bicuspid it is different. Even were the palatal part of theapprox-
imal surface removed till we reach a plane in line with the center of
the pulp, owing to the width of the tooth we could still always cut a
groove which would make a strong retaining formation, as seen in