Doug Kase
Figure 2: Follow-up radiograph
taken to verify which canal the instrument is in
Figure 4: Radiograph of the
completed fill (suitable for framing).
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 HERE
ARE TIMES when I look at an x-ray and discover root anatomy complicated
enough to make me exclaim, “Oy Vey!” The case that I’m going to discuss
in this column concerns one of those teeth that not only looks complicated,
but is also a challenge to our endodontic technique.
The tooth shown in Figure 1 is a perfect example of a lower bicuspid
that bifurcates in the apical one-third or one-quarter of the root.
The fact that coronally there is a common canal within one main root rather
than two separate canals within a common root makes every step—negotiation,
instrumentation, and finally obturation—a very tough endeavor.
Accessing the Bifurcated Canal
WHEN YOU GAIN ACCESS to the pulp chamber, it is important to open wide
enough to attain straight-line access to the canal. If the common
section of the canal is wide enough to begin with, then finding the split
toward the apex will be easier. Placing two instruments into the
tooth at the same time initially may be impossible. If the common
section is very thin initially, then—with copious irrigation and RC Prep—the
common section can be instrumented to a number 20 file or reamer and then
widened with Gates Glidden or Peeso reamers or a combination of the two.
After the widening is complete, access to the split canals will be easier.
A sufficiently wide coronal section will allow you
to place a small 45-degree bend in the initial instrument tip and then
rotate this tip into each end of the bifurcated canal. After you
have established a working length with an apex locator, you should take
a follow-up radiograph to verify which canal you are actually in (see Figure
2). It is important to remember how your initial instrument was inserted
into the common canal (for example along which wall) so that you can guide
it back into each of the splits properly.
Instrumentation can be achieved by alternating between
the canals with the same instrument. In other words, do not instrument
one side of the split totally for you will surely block the other side
with debris.
When you are alternating between canals, please
keep in mind the internal and external root anatomy. Your object
is to widen each canal and also to widen the common section of the canal
to allow a smooth transition into each split (see Figure 3). Widening
the common section with a number 2 Peeso reamer will enable you to accomplish
this transition, using the EZ Fill technique with the stainless steel series
of instruments, and ultimately the nickel-titanium instruments will also
pass easily into each split. You are now ready to obturate.
Obturation
TRYING TO OBTURATE this anatomical freak of nature may actually undo
all the good work you accomplished in the instrumentation phase.
By filling one canal perfectly, you may actually block access to the other
side of the split.
In the situation illustrated here, I was only able
to widen the coronal section enough to accommodate one medium gutta-percha
point at a time. However, due to the taper of the point and the widening
of the mid-root canal area, once the first point was placed to the apex
in one canal with EZ-Fill epoxy-resin cement I could remove the coronal
section of gutta-percha with a Peeso reamer. Then by using a very
thin stainless steel finger spreader as a path-finding instrument, I was
able to re-establish access to the other side of the split with ease.
Additionally, the thin finger spreader pushed the
mid-root mass of gutta-percha against the appropriate wall of the common
section of the canal, further facilitating the placement of a second medium
gutta-percha point.
When you have achieved the final fill of a case
as complicated as this one, the radiograph (see Figure 4) would be one
to frame as an 8 x 10 glossy and hang on your office wall.
March-April 2001
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Figure 1: A lower bicuspid
that bifurcates in the apical one-third or one-quarter of the root.
Figure 3: Each canal and
the common section of the canal widened sufficiently to allow a smooth
transition into each split.
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