Worldwide Assessment of the Mandibular First Molar Second Distal Root and Root Canal: A Cross-sectional Study with Meta-analysis

Martins J.N.R.; Nole C.; Ounsi H.F.; Parashos P.; Plotino G.; Ragnarsson M.F.; Aguilar R.R.; Santiago F.; Seedat H.C.; Vargas W.; von Zuben M.; Zhang Y.; Alfawaz H.; Alkhawas M.-B.A.M.; Altaki Z.; Berti L.; Boveda C.; Cassim I.; Chaniotis A.; Flynn D.; Gonzalez J.A.; Kottoor J.; Monroe A.; Silva E.J.N.L.; Versiani M.A. · Journal of Endodontics (2022) · DOI: 10.1016/j.joen.2021.11.009

Resumen

Introduction: This study assessed the prevalence of radix entomolaris and 2 canals at the distal aspect of mandibular first molars among different geographic regions by means of cone-beam computed tomographic imaging. Methods: Precalibrated observers from 23 worldwide geographic locations followed a standardized screening protocol to assess 5750 cone-beam computed tomographic images of mandibular first molars (250 per region), gathering demographic data and recording the presence of radix entomolaris and a second canal at the distal aspect of teeth. Intra- and interrater reliability tests were conducted and comparisons among groups were performed using proportions and odds ratio forest plots. The significance level was set at 5%. Results: The results of intra- and interrater tests were above 0.79. The prevalence of radix entomolaris varied from 0.9% in Venezuela (95% confidence interval [CI], 0%–1.9%) to 22.4% in China (95% CI, 17.2%–27.6%). Regarding the proportion of a second distal canal, it ranged from 16.4% in Venezuela (95% CI, 11.8%–21.0%) to 60.0% in Egypt (95% CI, 53.9%–66.1%). The East Asia subgroup was associated with a significantly higher prevalence of an extra distolingual root, whereas the American subgroup, the American native ethnic group, and elderly patients were linked to significantly lower percentages of a second canal at the distal aspect of teeth. No significant differences were noted between male or female patients. Conclusions: The overall worldwide prevalence rates of radix entomolaris and a second canal at the distal aspect of the mandibular first molar were 5.6% and 36.9%, respectively. The East Asia geographic region and Asian ethnic group had a higher prevalence of a second distal root.