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APPROXIMAL CA VITIES IN INCISORS. 109

which encroaches upon both the labial and the palatal surfaces. Where
these cavities are extensive, as pictured, they are usually trying. The
question has been raised by some authorities as to whether or not the
whole corner should be removed. I have already sufficiently expressed
my own views upon this. If in either of the previous two cases we
gained anything by the presence of the labial or palatal wall which
remained intact, what are we to do here in the absence of both ? In
each of the other cases I argued that the groove which I advocate is
not for retention, but to facilitate filling. Consequently, in the present
instance, when both walls are absent, we may still feel safe with pre-
the same labio- and
cisely arrangement, palato-gingival extensions at
a and b, a slight concavity at d, and a groove as before. The ques-
tion now arises, Shall this groove be placed at the labial or at the
palatal border of the cavity ? The answer indicates the method of
proceeding with the filling, for the groove is only intended as a leading
gutter for the gold as we pass from the gingival toward the incisive por-
tion. In this instance we place the groove along the palatal border c,
for that becomes the distant portion, and must be filled prior to the
labial.
I have said that this will be safe, but it will be so
arrangement only
so long as the natural corner remains intact. Elsewhere I have said
that the filling must be so strongly anchored above that, in case of
subsequent loss of the natural corner, a gold substitute may be built
on without removal of the original filling. To accomplish this the
labio- and extensions must be made as as
palato-gingival deep possible
with safety, and must continue as deep grooves toward the incisive end,
relatively about as far as f on the labial aspect and c at the palatal.
The upper half of the filling is thus securely held in three directions,
the palatal, the gingival, and the labial.
In after the upper retainers and building along the
filling, connecting
border into the incisive care must be taken to restore
palatal concavity,
the lost palatal wall before attempting to fill the main part of the cav-
In the so that presently the
ity. plainer language, manipulate gold
cavity, partly filled, will appear similar to that in Fig. 113, where, the
wall I said the becomes and
palatal being intact, filling simple easy.
If another method be pursued and the whole of the cavity be floored
over first so that it is lined with gold, we but add to our work, for we
simply reduce the size of a difficult cavity without altering its shape.
When half completed, the continuance will be more difficult than
the beginning, whereas in the method which I advise we constantly
lessen the task, making the cavity simpler and simpler as we continu-
ously alter the shape. But even by this method only the most skillful
operator can have a perfect filling when he has placed the last pellet
the labial border e, so that the work seems ended. Examination
along