August 2002 – Three Canals in a Single Rooted Mandibular Premolar
Fig. 1 - Preop
August's Case of the Month deals with complex anatomy in a mandibular second premolar. The case was referred to me having previously been accessed. I noted a small amalgam particle in the orifice bit I also was aware of the multiple vertical "lines" that appeared to be present along the "main canal". This either indicated a multiple root system or multiple canal system. A second film taken at a mesial angle did not assist me in analyzing the root structure since I could not "split" the roots with a shift shot. I then began to suspect a multiple canal system in a single root.
Fig. 2 - WL 1
Fig. 2 shows the initial examination of the canal system. I determined that the "main" canal was lingual and that I had at least one ( and possibly two) canals on the buccal aspect. I negotiated the distal with an .06 file.
Fig. 3 - WL 1
With persistence, ( I did NOT have a surgical microscope at this time - I am sure it would have been a lot easier had I been using one.) I located the mesial canal and increased the working length of the distal canal. I found that they all had a common apex. ( Fig.3)
Fig. 4 - GP Cones
Fig. 4 shows the cone fit/sealer film. It was interesting to note that even in this apparently small root and after shaping procedures, the coronal portion of all three canals were separate from each other.
Fig. 5 - Final Film
Fig. 5 shows the final obturation film. Although the coronal aspect of the canals were separate, the fill appears to be homogenous. What seems to be a "single canal" endodontic filling is much more complicated that it appears.
(I acknowledge that the films taken in this case are "foreshortened" , far more than I would like.)
Summary
We are all familiar with multiple roots in premolar teeth. The classic cases is the maxillary premolar with three roots and three canals (the "mini-molar" - with apologies to Austin Powers !) These can be very tough to treat.
However, we must always be aware that single rooted premolars can have variable numbers of canals. Close examination of the preoperative films can assist us in providing clues to the numbers of canals present. Correct access strategies then optimize our ability to negotiate these cases. This case is not a candidate for "conservative" endodontic access. You need to be able to see into the orifices. Had the tooth been crowned, I would have likely requested that the crown be removed before making access.
