Allan Deutsch
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HAS BEEN my experience that the most common cause of clinical failure in
endodontics is missed or uninstrumented canals. In other words, anatomy
is king in endodontics. If you do enough root canals and you are
on the lookout for three-rooted maxillary bicuspids, you will see them.
The key is to get into a routine that makes it easy to spot them.
I recommend that you take two starting films for each
tooth. These x-rays have a twofold purpose. The first is for
diagnosis and to establish etiology that justifies root-canal therapy as
the correct treatment for this tooth. The second purpose is to gain
as much information about the tooth as possible in order to facilitate
the treatment. You will want to know:
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How big is the pulp chamber?
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Are the canals open or calcified?
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How many roots (and canals) does the tooth have?
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Does decay go directly into the canal? This will make the canal orifice
harder to find.
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Are there any bent or malformed or malposed roots in the tooth?
One of these x-rays should be straight on, preferably
using a Rinn aiming device, and the other x-ray should be angled from the
mesial or distal to look for extra roots. Teeth that commonly have extra
roots are: mandibular molars, mandibular bicuspids, and maxillary bicuspids.
This case report deals with a maxillary first
bicuspid (tooth #12). The patient presented with hot and cold sensitivity
and sensitivity to biting and tapping on the tooth. A new composite
inlay had been placed one month earlier. Diagnostically, the tooth
was yelling for endodontics. On the starting x-ray (Figure 1) we
could see a hint of three roots. This does not occur too frequently.
We took another x-ray, angled this time. However, my regular assistant
was on vacation and my temporary assistant’s x-ray was overlapped and diagnostically
useless. Rather than expose the patient to more x-rays, I made the
assumption that this was a three-rooted bicuspid and decided that I would
look for all three canals when I opened the tooth.
When looking for extra canals or roots it is almost
mandatory to employ some type of optics. I use Designs for Vision
loupes. I use a 2.5 x wide-field to find the mouth, and a 4.5 x wide-field
when I am looking for canals. The microscope comes in handy for calcified
canals. These optics will save you subsequent visits and consequently
earn you more money on your cases.
I made the access cavity in the standard oval shape
for a bicuspid. The oval went from just before the buccal cusp tip
to just in front of the palatal cusp tip (Figure 2). I used a number
4 round bur to make the rough prep, and then I used a non-end-cutting barrel
diamond to smooth and shape the axial walls of the access prep. A
drawing of the floor of the pulp chamber when I first opened it up can
be seen in Figure 2. Upon initial opening, I could probe only a single
canal. I found it in the mesial buccal area of the chamber floor.
“O. K.” I said to myself, “I’ve got one canal. Where are the others?”
If this was truly a “minimolar,” there should be
a palatal canal somewhere. On the palatal side I just saw a dark
line (Figure 2). Since most canals are found directly under the cusp
tips and along the dark lines, I decided to push the access opening
more toward the palatal. I was happy to find the canal directly under
the cusp tip where it should have been. I then proceeded to clean
out and instrument both the MB and palatal canals. I have found
that once the canals are instrumented the large orifices make it easier
to place and find the missing canal. Also, during the course of instrumentation,
the sodium hypochlorite cleans out all the debris and stops any bleeding.
This gives you a very clear field to look for the missing canal.
All canals in general can be found in or along the
dark line or area found on the chamber floor. I now took my barrel
diamond and opened the area around the dark line on the disto-buccal side
of the tooth. Since there was vital tissue in the canal, I could
see a blood spot. The rest of the floor had been cleaned by the sodium
hypochlorite. That was the canal. I now instrumented it fully
using the EZ-Fill® SafeSiders® technique. The instrumented
floor of the canal can be seen in Figure 3. The tooth has a compressed
molar appearance. The orifices for the buccal canals were about 1.5
millimeters apart in a mesial distal direction.
The tooth was filled with gutta percha and EZ-Fill
resin cement using the EZ-Fill bidirectional spiral. The tooth was
closed with glass ionomer cement, the patient was sent back to the referring
general dentist for a permanent restoration, and Figure 4 shows the end
of another happy tale of endodontic therapy.
September-October 2003
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FIGURE 1: The starting x-ray
showed a hint of three roots.
FIGURE 2: Showing the access
cavity and the floor of the pulp chamber.
FIGURE 3: Showing the instrumented
floor of the canal.
FIGURE 4: The end result.
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