Clinical detection of the minor mesiobuccal canal of maxillary first molars

One hundred extracted maxillary first molars from a South East Asian population were sectioned at a level below the roof of the pulp chamber. The detection of the minor mesiobuccal canal was determined on the pulpal floor using a size 08 file. When the canal was not detected by this technique, its presence or absence was then determined by sectioning the mesiobuccal root transversely, and the position of the extra canal was explored from the cut end. It was found that by modifying the outline of the access cavity, and by widening and deepening the groove running palatally from the major mesiobuccal canal up to a depth of 0.5 mm and a distance of 2.0 mm, the visibility of the extra mesiobuccal canal orifice was greatly improved. This study showed that more than 50% of maxillary first molars had a minor mesiobuccal canal, and 19% of these canals could not be detected clinically.