Variations in the normal anatomy of the inferior dental (mandibular) canal: a retrospective study of panoramic radiographs from 3612 routine dental patients.

A review of 3612 panoramic radiographys from routine dental patients indicates that the mandibular canals are usually, but not invariably, single and bilaterally symmetrical. The position of the canal varies with respect to the lower border of the mandible and the apices of the roots of the teeth and this excludes its use as a set reference point for prosthetic or orthodontic assessment. Three distinct varieties of supplemental mandibular canals, large enough to be seen on panoramic radiographs, are described.