Prevalence of C-shape Canal in Second Mandibular Premolars: A Systematic Review and Meta-analysis

Abstract

Objectives: C-shaped root canal morphology presents significant challenges in endodontic treatment due to its complex anatomy. This systematic review and meta-analysis evaluated the prevalence of C-shaped canal anatomy in mandibular second premolars and examined the influence of geographic variation on prevalence rates. Materials and Methods: The study followed Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, systematically searching five electronic databases: PubMed, Web of Science, ScienceDirect, Scopus, and Google Scholar. Eligible studies included cross-sectional, prospective, and observational studies on C-shaped canal prevalence in adult mandibular second premolars. Statistical Analysis: A random-effects model in RStudio software was used to calculate the pooled prevalence and 95% confidence intervals (CI) of C-shaped canals. Results: The pooled prevalence based on participants was 1.31% (CI: 0.68–2.53; I² = 90%; P < 0.01). Based on the number of teeth, the prevalence was 0.96% (CI: 0.46–2.00; I² = 93%; P < 0.01), also with high heterogeneity. Geographic analysis showed the highest prevalence in South America 5.83% (CI: 0.57–40.04; I² = 95%; P < 0.01) and the lowest in Australia 0.42% (CI: 0.31–0.93). Conclusions: The study demonstrated variability in the prevalence of C-shaped canals, with a pooled estimate of 1.31% based on participant-level data and 0.96% based on tooth-level assessment. The substantial heterogeneity observed across studies highlights the morphological diversity of root canal systems. Geographic differences were observed, with the highest prevalence in South America and the lowest in Australia. These findings underscore the importance of region-specific diagnostic vigilance.