October 2002 – Technique Adjustment for a 5-Canal Mandibular Molar

Fig. 1 - Prior to access	October's case of the month (Fig. 1) shows another mandibular first molar in a 24 year old female patient. The large amalgam was loose and there was recurrent decay under the restoration.
Fig. 2 - Working lengths - Note 2 files mistakenly placed in the MB canal	After establishing access, I immediately noticed that there appeared to be 3 mesial orifices. This film ( taken with a mesial shift) shows 2 files in the MB ( I missed placing the file in he "middle" mesial canal in this film. I also noticed that the distal file did not appear to be centered in the root. The distal root also had a disto-lingual canal, making a total of 5 canals. (Fig. 2)
Fig. 3 - GP Fit - Mesial Shifted film	The canals were cleaned and shaped with hand files and reamers using standard Boston U. technique. I was reluctant to use Ni-Ti rotary files in this case because of the close proximity of the canals and likelihood of canal anastomoses. Although the hand file technique is slower, I believe in this case, it offered less chance of instrument fracture.
Fig. 4 - Final Film - Mesial shift	Figure 4 shows the final result. It appears that there are 3 separate canals in the mesial root with three separate foramina. The distal root shows 2 canals with interconnections along the midroot and separate foramina. A post space was prepared in the DB canal with a #3 Gates Glidden bur.

Conclusion
Very satisfactory results can be achieved with different shaping techniques. Ni-Ti Rotaries have shown to be excellent in handling cases where roots are long and curved. However, sometimes the anatomy of the tooth is not as straightforward as we think it is. We occasionally come across situations where files "seem to go all over the place" when they are placed in the canals. Canals may be noticeably joined at the midroot and not just at the apex. ( The classic C shaped mandibular molar is an excellent example.) If a Ni-Ti file is placed in one canal and its tip catches in the opening in the 2nd adjacent canal, it can easily break, blocking both canals.In those cases it is necessary to adjust cleaning and shaping or obturation techniques to compensate for unusual anatomy or when rotary techniques run increased risk of breakage. This tooth presented for endodontic treatment and is effectively managed by altering technique to account for the different types of canal anatomy.

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