Abstract
The aim of this prospective study was to determine the number of canals treated in the mesio-buccal roots of the maxillary first and second molars teeth of a Saudi Arabian population during a 1-year period in a postgraduate endodontic program. The attending endodontic faculty member supervising the case verified the number of canals in the teeth clinically and radiographically. In total, 308 maxillary first molars and 162 maxillary second molars, of which 158 (51.3%) and 32 (19.7%) met the criterion of having two canals detected and treated in the mesio-buccal root of the maxillary first and second molars, respectively. It was concluded that the occurrence of mesio-palatal canal in the mesio-buccal root of the maxillary first and second molars of a Saudi Arabian population was high. The fact that almost more than half the mesio-buccal roots of the maxillary first molars bear two canals is enough reason to always assume that two canals exist until careful examination proves otherwise.