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

Introduction: This cross-sectional study assessed the influence of patient demographics on the worldwide prevalence of a lingual canal in mandibular incisors. Methods: 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%). Results: 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 < .05), while Caucasians, Indians, and Arabs showed the highest (P < .05) for both incisor groups. Additionally, males had a significantly higher odds ratio for both the central (1.334) and lateral (1.178) incisors, while older patients had a lower prevalence for both tooth groups (P < .05). The side and tooth group did not influence on the outcomes. Conclusions: The prevalence of lingual root canals in mandibular incisors varies significantly based on geographic location, ethnicity, age, and gender. The overall prevalence was 21.9% for mandibular central incisors and 26.0% for lateral incisors.