Allan Deutsch
 
 
 
 
 
 
 

NE of the more difficult parts of the endodontic procedure is knowing how many canals there are and finding them. The morphology for each type of tooth is generally consistent for teeth in that category: molars, bicuspids, canines, laterals, and centrals. However. each category will have variations within its own group. These variations within each group will fall into several repeatable morphologies.
     The case I will describe is a mandibular bicuspid. The usual morphology for mandibular bicuspids is one canal. However, the variations can be two canals or the very rare three canals. Naturally, the number of roots in which these canals are situated can also vary. The radiograph is often the key to finding all the canals. Lower bicuspids are very nice in that they will tell you on the x-ray if there is more than one canal. The trick is to know what to look for.
     Figure 1 is a drawing of an x-ray. When you see a large canal in the coronal to middle half of the tooth and then it disappears, the x-ray is telling you that there are at least two canals. If we could rotate the tooth 90 degrees, we would see that at point A, where the canal seems to disappear, in reality the canal splits into two canals. This split is demonstrated quite nicely in Figure 1.
     A good example of this morphology is found in the x-ray of tooth # 21 in Figure 2.
     The non-endodontically treated bicuspid demonstrates this telltale x-ray appearance very well. We can easily see the large canal disappear at about the middle of the root. With this background, let’s look at a not-so-typical case.
     This patient presented to the office with the access on tooth # 21 already opened by a general dentist (Figure 3).
It was difficult for me to tell whether this was the real appearance of the canal and chamber or an artifact created by the access opening. My gut feeling from the x-ray was that this was a two-canal bicuspid. I looked for quite some time but did not find another canal. I then instrumented the first canal, which appeared centered in the root (or so I thought). After complete instrumentation, I looked again for the canal, but to no avail.
     Essential Dental Systems has a new epoxy cement. It is called EZ-Fill Xpress®. It is an epoxy, that is a gel, packaged in an auto-mix double-barrel syringe. This epoxy cement is even more radio-opaque then the powder gel formulation of the current EZ-Fill Xpress sealer. I thought that perhaps once I had obturated the first canal the cement might go into the second canal and show me the location of the orifice. Figure 4 shows the result of the obturation.
     From this head-on view I did not see very much. However, I was still not convinced that there wasn’t another canal.
     I asked my assistant Nichelle to take a very angled x-ray to try to split the roots and show us whether we had had any success (Figure 5). Sure enough, we got very lucky; you can see the line of EZ-Fill sealer Xpress going down the canal (on the left of the filled canal). Once I found the canal (way, way over to the lingual), it was an easy matter to instrument and fill. Figure 6 shows the final result. The situation is much better than that shown in Figure 4. In Figure 6, you can even see the outline of the two roots. Thank you “increased radio opacity”!

FIGURE 1: Cracked finger due to excessive dryness and washing irritation.




FIGURE 2: A good example of the split-canal morphology (tooth on left).

FIGURE 3: Showing the access to toth # 21 already opened.

FIGURE 4: Showing the result of the obturation.

FIGURE 5: A highly angled x-ray reveals a line of EZ-Fill sealer on the left of the filled canal.

FIGURE 6: The final result, with the outline of the two roots visible.