Page 192 - My FlipBook

1 7 8 ME THODS OF FILLING TEE TH.
labial, because of the line of approximate bifurcation seen from this
view. This makes it possible that the canal within may be divided,
the bifurcation of a pulp usually being coincident with that form of
root. This figure also shows a distinct curve near the apex, and
exhibits the danger that would accompany the free use of any style
of drill that has a point allowing it to make forward cutting.
The central in the inferior jaw is usually found with a broad, flattened
a concaved extend-
root, which, viewed from the side, presents groove
ing the full length of the root. This groove is very significant, for it
is the lateral wall of the canal, so that it follows that the pulp-canal is
the narrowest diameter of the tooth. We must also note that these
lateral walls are quite thin. If a canal-reamer were used which had a
bur-head it would
larger than this narrow diameter of the tooth,
follow of necessity that this lateral wall would be punctured, so that it
is not alone the of a canal instrument which offers a
forward cutting
danger of opening through the roots of teeth. It would rarely if
ever be necessary to use a drill or reamer in the lower incisors, because,
as seen in Fig. 204, though the canal is flattened laterally, it is usually
wide enough in the other direction to afford ample space for cleansing
and subsequent filling.
Lateral Incisors. The roots of superior lateral incisors almost
invariably terminate in a crook at the apex which curves posteriorly.
In Fig. 205 is shown a curious example. Judging by the general
direction of the crown, the course of the root could not be guessed at
all. The root curves toward the median line of the mouth at a con-
at the the rule above stated is found
siderable angle, yet apex exempli-
fied, there being a crook which turns posteriorly. It is probable that
the root of this tooth was upright when in the alveolus, the crown
appearing irregularly curved toward the centrals. Were it not dis-
covered that this curve of the root existed, it is evident that were the
root drilled, the instrument might emerge somewhere about half-way
between the crown and root-end.
Fig. 206 shows another lateral incisor, where we find a crown not
than in the last case, whereas the root is much
much larger longer.
Again is seen the posterior crook at the extremity. An approximal
view of this root would show also an apical curve toward the labial
of the alveolus.
plate
The lateral incisors of the inferior jaw do not materially differ from
the centrals, except that they are slightly larger.
The filled of all
Cuspids. cuspid is usually the most readily pulp-
less teeth. Ordinarily the canals are proportionately large and
moderately straight, and one feels fairly satisfied that at least in this
tooth the canal may be filled to the extremity. Yet take a handful of
and an examination of them out of the mouth will show so
cuspids,