Bilaterality and Symmetry of C-Shaped Mandibular Second Molars in a Mexican Maya and Non-Maya Population: A CBCT in vivo Study/Bilateralidad y Simetria de los Segundos Molares Mandibulares en Forma de C en una Poblacion Mexicana Maya y no Maya: Estudio in vivo Mediante CBCT

The objective of this study was to evaluate the bilaterality and symmetry in C-shaped mandibular second molars in Mexican Maya and non-Maya populations using cone-beam computed tomography(CBCT). Five-hundred-twenty-five CBCT scans of patients with left and right mandibular second molars were analyzed to determine the prevalence and bilaterality. The teeth were assessed for the presence of C-shaped root canals, according to Fan et al. (2004) criteria. The sample was subdivided by ethnicity, sex, unilateral/bilateral presence, side of the longitudinal groove, and the C-shaped root canal configuration and symmetry, at the cervical, middle, and apical crosssections of the root. C-shaped mandibular second molars were present in 24.95 % of the individuals. Most (60.30 %) of those showing this trait had it bilaterally. When comparing by ethnicity, sex, and side, we detected no significant differences. The vast majority (97.33 %) presented the groove along the lingual side. The C3 was the most prevalent configuration in the overall sample, while in the Maya group, the C1 was the most common configuration. When analyzed by sex and ethnic group, the non-Maya females tended to deviate from the other groups in terms of bilaterality. Overall, 55.70 % of bilateral C-shaped mandibular second molars were also symmetric in the three radicular thirds. The prevalence of C-shaped mandibular second molars was similar to that reported for northern Asian populations, which is consistent with the evolutionary origins of Native American populations. Most of the sample showed bilaterality and half were symmetric. Clinicians must be aware of the ethnic background of their patients and consider the possible variations to do more predictable root canal treatments. KEY WORDS: Bilaterality; C-Shaped root canal; Mandibular second molars; Maya ethnicity; Symmetry