Abstract
The maxillary first premolar commonly has one or two root canals; the presence of three canals is rare. These root canals are easily missed during treatment, resulting in failure of root canal therapy. The present report describes a case in which three root canals in the maxillary first premolar were diagnosed by cone-beam computed tomography. The herein-described patient was successfully treated using three-dimensional reconstruction technology to determine the form and direction of curvature of the root canals.