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BICUSPIDS.
141

portance. Occasionally we may be able to anchor a filling of this
that we
nature so securely may be satisfied to risk a full contour.
Where it can be done, the procedure is as follows. The removal of
all would us a of somewhat
decay give general concavity irregular
shape.
each
Begin by forming deep grooves along approximal wall, as
indicated at a, a, in Fig. 159. Unite these with a groove around the
labial wall, as at b. This will give a groove of horse-shoe shape.
Make extensions at the labio-approximal angle on each side, as deep as
safety will permit. Note that the groove is a horse-shoe, the circle
not To do so would mean to extend the groove
being completed.
which would
along the base of the remaining cusp, greatly weaken it,
without affording adequate compensation for the risk involved. In
fact, except in rare cases, where the standing cusp is found unusually
strong, do not attempt any undercutting or grooving at this point at
FIG. 160.
FIG. 159.
FIG. 157. FIG. 158.

all. A of the whole inner surface of the
general concavity cusp, as
at c, will be sufficient to act with the opposing groove, and retain the
full contour. Or if not, then one or two gold screws should be em-
ployed. A first glance at Fig. 158 might leave the impression that the
filling would not remain in place because of the fact that only a single
retainer, b, is shown. It must be remembered, however, that this, which
here is at the palatal side of the tooth, is analogous to the groove at b
in Fig. 159, where it occurs at the labial. The section does not indi-
cate the lateral grooves, which would occur in such a case as Fig. 158,
as has been described in As to in
just Fig. 159. filling-materials,
such a case as Fig. 159 it seems to me that we must use gold, as the
contoured is to view. In Fig. 158, where the whole
cusp exposed
will be unseen, amalgam may be used under some circumstances,
filling
as for example in the mouth of one for whom a lengthy operation
would be a risk, because of shock. Ordinarily I should use gold in
either case. I should begin at the end of the distal groove, and, using
build around till the itselfwas solidly packed. Then I
pellets, groove
should build across, connecting the two arms of the horse-shoe groove,
so covering the floor of the cavity. Keeping my gold with a flat sur-
face, I should build up till on a level with the border where the cusp
was absent. Next work toward the remaining cusp, and cover it