Worldwide Prevalence of the Lingual Canal in Mandibular Incisors: A Multicenter Cross-sectional Study with Meta-analysis

This cross-sectional study assessed the influence of patient demographics on the worldwide prevalence of a lingual canal in mandibular incisors. Twenty-six thousand four hundred mandibular incisors were evaluated using cone-beam computed tomography imaging by precalibrated observers from 44 countries. A standardized screening method was employed to collect data on the presence of a lingual canal, the anatomic configuration of the root canal, and number of roots. Patient demographic information (age, sex, and ethnicity) was also recorded. Multiple intra and interrater tests assessed the reliability of the observers and groups, and a meta-analysis was used to examine differences and heterogeneities (α = 5%). The prevalence of the lingual canal in mandibular central and lateral incisors varied from 2.3% (0.06%–4.0%; Nigeria) to 45.3% (39.7%–51.0%; Syria) and from 2.3% (0.06%–4.0%; Nigeria) to 55.0% (49.4%–60.6%; India), respectively. Ethnicity had a significant impact on the prevalence of the lingual canal, with African, Asian, and Hispanic groups having the lowest proportions (P