Page 29 - My FlipBook

INTENTIONAL EXTENSION OF CAVITIES.
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groove is found with caries at the deepest point, it is essential to cut it
out thoroughly. Sometimes there may be no caries in the groove
itself, but an approximal cavity closely approaches it. This is shown
in Fig. 23, which gives the palatal aspect of a lateral incisor. The
border of the
palatal approximal cavity, a, closely approaches the end
of the sulcus, b. Ifwe fill the cavity without taking note of the sulcus,
it is that no future harm It is more
possible may supervene. probable,
however, that caries would occur in the groove, and burrowing under
the would loosen it. It might be claimed that when this occurs
filling
would be the time to attend to the case, but it must be remembered that
when a tooth has been filled, the generally accepted idea of the patient
is that it is safe as long as the filling remains in position. The final
loss of a filling by the burrowing of decay beneath it may be delayed for
Thus caries would be without
an indefinite period. progressing being
until a sudden that time the mis-
suspected pain gave warning, and by
chief would have been done, the pulp being either exposed or closely
approached. It is therefore preferable to fill the groove when treating
the The method of procedure is different
approximal cavity. slightly
from that which would be pursued for a molar. If we unite the cavi-
ties at the outset by a fairly deep groove, we would, especially in a
lateral incisor, produce a very weak point at c, which would be likely
to crumble under the mallet during filling. The better plan, therefore,
is to fill the approximal cavity first. This being done, prepare a
cavity along the sulcus decreasingly deep as you approach the ap-
proximal filling, just reaching that point and no more, making it as
shallow as would be consistent with strength.
The treatment of a somewhat similar condition upon the labial
surface must be quite different. Fig. 24 shows an incisor having an
approximal cavity (a) and a festoon cavity (3). The space (c} between
a weak and would be further weakened in
is necessarily point, pre-
the two cavities for the of It
paring reception separate fillings. is
much better to fill them as one cavity, cutting away entirely the
intervening enamel and dentine.
We now come to a most important subject, approximal cavities.
Are we under any circumstances to extend such cavities beyond the
borders outlined by the decay ? There are certain cases where it is
imperative, and others where such a course should be prohibited.
In the six anterior teeth the approximal cavities should be prepared as
small as possible, consistent with reaching strong edges. I am aware
that this is a dogmatic assertion and at variance with teaching of high
authority. Nevertheless my experience teaches me that this course
cannot be too emphatically insisted upon. Extension of approximal
cavities in incisors has been advised, in two directions. First toward
the gingiva, to reach a point anticipatory of the possible recession of