Page 199 - My FlipBook

PREPARING ROOT-CANALS.
185
at least I shall describe my methods of using reamers as I go along,
indicating where obstacles are to be met and how to avoid them.
' ' '
I have been asked, Can you drill around a curve ?' The answer
is that it can be done, and many times must be done.
that I am
Suppose using a reamer, and I feel a resistant spring to
do not strike the end that would
my instrument, yet against anything
indicate that I have reached the region of the foramen. I know at
once that the canal has a central curve in it, and that as soon as the
head of the reamer reaches this place, the curve of the wall diverting
the drill-head, makes a tension upon the flexible shaft so that I get a
response which I have described as feeling a resistant spring. This
is always a danger signal. Force the
FIG. 233. FIG. 234.
instrument a bit farther, and the shaft
will snap, breaking off the drill-head.
Worse than this, the broken
piece will
be at such an angle that it cannot be re-
moved. This is made Dia-
plainer by
gram 233, where the drill-head is seen
at a, in a position that makes its removal
impossible without very great enlarge-
ment of the cavity. Where this hap-
pens, it is evident that all the canal
beyond must remain unfilled. Conse-
quently, as soon as the springy resist-
ance is noticed the reamer must be
removed. If a small-sized Gates- Glid-
den drill has been used, the largest
size may be chosen to replace it. This,
having a stouter shaft, may have the
power necessary to successfully resist
the tension while the drill-head cuts
away the bulging wall at b. If it was
the sized drill that was in use
largest-
a in the first instance, it must be re-
I / placed by a fissure-bur of small size, with
which the upper bulge at c could be re
moved, after which the large Glidden
drill will readily remove the obstacle at
b. This accomplished by either method,
the drill can be advanced as far as d, be-
yond which it cannot be carried. The canal would
now present as in Diagram 234. During this work there will be the
danger already noted of clogging up by pushing forward debris.
This may and must be avoided. It results mainly from the desire