Prevalence of Radix Entomolaris in Permanent Mandibular First Molars Among the Saudi Population: A Systematic Review and Meta-Analysis

Abstract

Objective: Radix entomolaris (RE) refers to a supernumerary distolingual root that alters the root canal system of permanent mandibular first molars (PMFMs), complicating endodontic diagnosis and treatment. Although global prevalence data are available, population-specific estimates for the Saudi population remain heterogeneous and incompletely characterised. This systematic review and meta-analysis estimated RE prevalence in Saudi PMFMs, investigated sex-related differences and described bilateral occurrence where available. Methods: A systematic review and meta-analysis was conducted in accordance with PRISMA 2020 guidelines. The following electronic databases were searched from inception to March 2026: PubMed/MEDLINE, Scopus, Web of Science, and Google Scholar. Studies reporting tooth-level or patient-level prevalence of RE in PMFMs among the Saudi population, using either cone-beam computed tomography (CBCT) or periapical radiography, were eligible. The risk of bias was assessed using the Joanna Briggs Institute (JBI) Critical Appraisal Checklist for Analytical Cross-Sectional Studies. Meta-analysis employed a random-effects model (REML). Certainty of evidence was assessed using GRADE. Results: Fifteen studies were included. The pooled tooth-level prevalence of RE was 5.1% (95% CI: 4.0-6.2%; I2 = 85.7%; 95% prediction interval [PI]: 0.9-9.3%). The pooled patient-level prevalence was 6.9% (95% CI: 4.7-9.0%; I2 = 84.0%; 95% PI: 0.0%-14.1%). No statistically significant sex-related difference was identified at the tooth level (odds ratio [OR] = 0.991; 95% CI: 0.798-1.231) or the patient level (OR = 0.951; 95% CI: 0.680-1.331). Substantial heterogeneity was present across all analyses. Certainty of evidence was low for tooth-level and patient-level prevalence outcomes, per the GRADE framework. Conclusion: Radix entomolaris occurs in approximately 5.1% of PMFMs and 6.9% of patients in Saudi Arabia, representing a clinically relevant prevalence. These estimates differ from published international estimates and are broadly comparable to those reported in several Middle Eastern, European, and African populations. Sex is not a significant determinant of RE prevalence. Preoperative radiographic assessment of mandibular first molars, preferably using CBCT when clinically indicated, is recommended. Higher-quality, populationrepresentative studies are required to improve the certainty of evidence.