Evaluation of root anatomy of permanent mandibular premolars and molars in a Korean population with cone-beam computed tomography

OBJECTIVE: The purpose of this study was to investigate the root/number of roots and morphology of mandibular premolars and molars in a Korean population, and to evaluate the prevalence of three-rooted mandibular first molars having distolingual (DL) roots, three-rooted mandibular second molars, and C-shaped roots in mandibular second molars. METHODS: Serial axial cone-beam computed tomography (CBCT) images of the mandibles were collected from 430 Korean patients. The total number of roots in the mandibular premolars and molars was counted, and the incidence and the correlations between left- and right-side occurrences and between males and females were analyzed. RESULTS: The majority of mandibular first premolars and second premolars had one root (99.9% and 99.4%, respectively). Three-fourth of first molars (77.4%) had one mesial and one distal root, and the incidence of a three-rooted tooth having DL root was 22.3%. A little more than half the number of mandibular second molars (54.5%) were two-rooted. Finally, 2.3% of the second molars had three roots having one DL root, and 41.3% had C-shaped roots. CONCLUSION: There was a high prevalence of three-rooted mandibular first molars and C-shaped roots in mandibular second molars among a Korean population, detected using CBCT, and the results showed similarities with previous reports about other Asian populations. It may be suggested that CBCT is a practical method of evaluating the number and shape of teeth. Data regarding the occurrence and morphology of the roots may provide useful information to dental practitioners.