Root Anatomy and Root Canal Morphology of Maxillary Second Permanent Molars in a Chongqing Population: A Cone-Beam Computed Tomography Study

BACKGROUND To investigate variations in the anatomy of root canals in permanent second molars of the upper jaw in a population in Chongqing, China, using cone-beam computed tomography (CBCT). MATERIAL AND METHODS CBCT imaging data of 400 second permanent molars of the upper jaws of 200 patients were retrospectively reviewed. Patients' gender, age, numbers of roots and canals, root fusion of permanent second molars of the maxilla on both sides, and morphological categories of root canals of mesiobuccal roots were recorded. The distances from the apices of the distobuccal and mesiobuccal roots to the buccal bone plate were measured. RESULTS Of the 400 permanent second maxillary molars, 312 (78.0%) had three roots and 247 (61.75%) had three canals. Fused roots were observed in 126 (31.5%) teeth; of these, 67 (53.2%) had three canals and 44 (34.9%) had two canals. Morphologically, 297 (74.25%), 29 (7.25%), nine (2.25%) and 65 (16.25%) teeth had type I, II, III, and IV mesiobuccal root canals, respectively, with 103 (25.75%) having secondary mesiobuccal canals. The distances from the apices of the mesiobuccal, distobuccal, and single buccal roots to the surface of the buccal osseous lamella were 7.34±1.89 mm, 6.26±1.74 mm, and 8.60±2.56 mm, respectively. CONCLUSIONS The root form and canal shape of permanent second molars of the upper jaw varied greatly among the population of Chongqing, China. CBCT is a valuable method for assessing the complex anatomic morphology of teeth.