Page 407 - My FlipBook

METHOD OF OPENING THE CAVITY. 405

should be first carried on at the sides of the cavity, and also along the
margin of the cervical wall in approximal cases. Then the carious
matter nearest the pulp should be carefully peeled oif without pres-
sure and without irritation. In this manner a pulp may be uncov-
ered and the cavity cleansed of carious matter w^ithout contact being
made with the pulp. To do this is the acme of skilful preparation.
The instruments for removing caries should be of thin edge, very
sharp, and always having cutting surfaces which are rounded, since
angular or square-ended excavators are liable to make exposures un-
necessarily. It is important that the direction of movement of the ex-
cavators should be from the cervix toward the occlusal part—in other
words, by drawing cuts instead of pushing ones. The diiference in the
excitement of pain between these two methods of cutting is surprising,
and can only be appreciated by those Avho have experienced the com-
parison upon their own teeth. The probable reason for this is that the force
of the pushing cut is necessarily greater, and this may induce com-
pression of the caries or of fluids against the pulp. It causes more
pain at the moment, and cleansing in this manner is followed by greater
after-irritation. Patients will at the time complain of reflected pain
being caused by incorrect manipulation.
It is obvious that every mode of procedure which increases the local
irritation in the preliminary procedures of a pulp treatment must be
deleterious in its results. The danger of making accidental exposures
and of forcing the instruments upon the pulp are increased under push
cutting. It is also clear that the use of burring instruments upon the
pulp wall of cavities is questionable, since the infliction of some com-
pression by excavating in this manner is nearly unavoidable.
Here an interesting question appears A cavity may be sufficiently
:
it has been carefully cleansed of caries, and
deep to cause an exposure ;
the cornua are not apparent. It is then necessary to determine whether
there is a real but minute exposure or whether there is a safe amount
of healthy dentin to protect the pulp beneath the stopping material.
One method is to eross-hafcJi the cavity by a very fine explorer.
This is eifected by holding the instrument very lightly and passing
it gently over the surface in parallel lines in two directions. If the
pulp has been reached, the instrument at the point of encroachment
will lose its resistance or will drag the point of the cornu, as the case
may be.
While there may be no visual evidence of exposure, the certainty of
it is frequently shown during the preparation of the cavity or the test-
ing by a peculiar expression of the face of the patient, diflerent from
that manifested by the cutting of the most exquisitely sensitive dentin.
This change of the countenance, accompanied by a slight start of the