Page 203 - My FlipBook

PREPARING ROOT- CANALS.
189
of the canal in a somewhat
broader parts peculiar way. I use the
Glidden drills as though there were two canals, exchanging to larger
and larger drills until the two sides are as thoroughly cleansed as
possible. This done, I take the smallest of the Glidden set, and,
beginning at the coronal extremity of the canal, I pass the drill
from one side of the canal through the narrow passage to the other.
This is and the extent of
carefully repeated, passing higher higher up
the canal, until I either clear it throughout or else receive some inti-
mation that it would be unwise to proceed further, for it must never
be forgotten that this tooth also may be bifurcated, at least near the
extremity. The least signal of pain from the patient makes it wise to
work.
stop
The lower bicuspids are often peculiarly difficult because they may
be in some abnormal position, the most common and troublesome of
which is a tipping inward, so that the labial surface is really partly
occluding with the upper teeth. It is plain that in such a pose nothing
would be gained by opening through the crown with the hope of using
a Glidden drill. Where the cavity is in an approximal surface, however,
such extension is often necessary even for the use of a broach, and
occasionally the Pettit reamer may be used to advantage. Where the
cavity is approximal, but near the gum only, or where it is similarly
situated at the labial side, extension must be made along the posterior
approximal angle toward, but not necessarily into, the crown. Where
it is peremptory to use a drill, as in a case of abscess where the canal
is badly narrowed and stopped with secondary dentine, the extension
must then follow the center of the labial face, even though it be dis-
figuring. It is an awkward procedure, but desperate cases demand
desperate remedies, and, besides, the labial face of a lower bicuspid
is well hidden from view ordinarily.
Molars. Superior molars having approximal cavities are made
accessible by cutting through to the crown. When the cavity occurs
elsewhere, but not in the masticating surface, the canals are to be
reached not through the original cavity, but through a special open-
ing through the crown made for the purpose. The thorough opening
of a pulp-chamber will often require the sacrifice of considerable tooth-
substance ; but this, though a pity, is unavoidable. No sentimental
ideas should tempt the dentist to hesitate to make the opening com-
Where the is at the posterior approximal sur-
plete. original cavity
face, some difficulty will be met in cutting through the crown far
enough to gain access to the anterior buccal root. The easiest method,
and one which will save much distress to the patient, as well as time
is as follows: With a drill a
and labor for the operator, sharp spear-drill,
hole straight to the pulp-chamber through the anterior sulcus. The
condition at this point is shown diagrammatically at Fig. 235, which