Evaluation of the Root and Canal Morphology of Mandibular First Permanent Molars in a Western Chinese Population by Cone-Beam Computed Tomography

Introduction: The purpose of this study was to evaluate the root and canal morphology of mandibular first permanent molars in a western Chinese population by using cone-beam computed tomography (CBCT). Methods: In this study, 558 samples were examined by CBCT. Details of sex, tooth position, the number of roots and canals, and the canal configuration were recorded. The root canal configuration was categorized and compared according to Vertucci's criteria. Results: Overall, 51.4% of the mandibular first permanent molars examined had four canals, and 25.8% had a separate distolingual root. In 48.1% of these, the fourth canal was in the separate distolingual root. In the two-rooted mandibular first permanent molars, 93.9% of the mesial root canals were of type IV, and 62.9% of the distal root canals were of type I. In the three-rooted samples, 94.4% of the mesial root canals were of type IV, and 98.6% of the distobuccal and 100% of the distolingual root canals were of type I. In addition, there was a higher incidence of three-rooted mandibular first permanent molars on the left side than on the right, but this relationship was not significantly correlated with sex. Conclusions: Mandibular first permanent molars commonly have four canals and a higher prevalence for a separated distolingual canal in a western Chinese population. (1 Endod 2010;36:1786-1789)