Page 202 - My FlipBook

1 88 METHODS OF FILLING TEETH.

through the crown will serve the purpose adequately and save refilling
a difficult cavity.
all the
In the first bicuspid peculiarities of form are to be borne
in mind, and
constantly procedure should be slow and careful.
Partial cleansing may disclose the fact that the coronal end of the
canal is as represented in Fig. 211. The next point will be to
determine just how deep the communicating passage b extends, and
therefore how far it will be safe to connection of the
attempt thorough
two canals, for as two canals they should always be treated at the
outset. In a few cases it will be possible to unite them throughout.
Most often it will be safe to use a rose bur as far as the neck
freely
of the tooth. Beyond that explorations should be made with fine
broaches, passed up one canal and then forced across into the other,
where the passage exists. This will prove a guide, but stiff-shanked
burs must be discarded for working farther up in the canals, a
serving better, because, whilst resistant enough
slender Glidden drill
to clear out and enlarge any passage which may exist, it will be found
difficult with such a tool to cut through solid material. Where the
rose bur or fissure-bur is recklessly used for this place, the inevitable
result will be that sooner or later the dentist will make an opening
near the of the bifurcation of a double-rooted tooth, or
beginning
even in one that has only bifurcation of the canals, the roots being
coalescent, as in Fig. 213. The palatal canal will not be so difficult
to cleanse as the labial, and in this latter, drills are to be used with the
utmost caution if employed at all. The position of the patient and
the tip of the tooth will generally be such that in forcing the drill into
the labial canal it will necessarily bend, and to revolve a slender steel
shank under such circumstances is to invite a fracture.
On the other hand, the drill will be more easily used after the coronal
end of the canal has been thoroughly enlarged, for the reason that,
"
more in which to it will be less to bend.
having space play," likely
Sometimes the cavity in the crown itself may be enlarged, so that the
drill will more enter the canal. it should be
directly When this can,
done. The treatment of curved extremities is the same as with the
anterior teeth, the Evans root-drier the
being dependence.
The second bicuspid in the superior jaw is usually a single- rooted
tooth. Nevertheless, here also the coronal opening will frequently
be as in Fig. 211, and once more the narrow connecting passage at
b becomes a for is
point study. This root, though single, generally
broad and flattened, and viewed out of the mouth often has the pecu-
attributed to lower incisors, there a
liarity being depressed groove
corresponding with the center of the inner canal. Thus it is seen
that with
throughout the canal the walls on either side, corresponding
b in the diagram, are the thinnest part of the tooth. I unite the two