# Prevalence of c-shaped canal morphology in premolar and molar teeth assessed by cone-beam computed tomography: systematic review and meta-analysis

## TL;DR

This study finds that c-shaped canals in molars are most common in Asian women's mandibular second molars, using cone-beam CT scans.

## Contribution

A systematic review and meta-analysis of c-shaped canal prevalence in premolars and molars using CBCT data.

## Key findings

- The highest c-shaped canal prevalence was in mandibular second molars (17.3%) and lowest in maxillary first molars (0.8%).
- C-shaped canals in mandibular second molars were more common in Asian populations and in women (23.6% vs. 16.7%).

## Abstract

This systematic review aimed to investigate the prevalence of c-shaped canal in mandibular and maxillary premolars and molars using cone-beam computed tomography (CBCT) and the effect of factors (e.g., gender, geographic region and position in the jaw) on the prevalence of this anomaly.

A search was conducted in 3 databases (PubMed, Scopus and web of science) and studies were selected based on inclusion and exclusion criteria. The inclusion criteria were studies that investigated the prevalence of C-shaped canal using CBCT images until 2024. The I2 statistic was performed to determine heterogeneity and meta-analysis was conducted.

Of 5548 studies, 101 studies were selected for meta-analysis based on inclusion criteria. The highest prevalence of c-shaped canal was in the mandibular second molar (17.3%) and the lowest prevalence was in the maxillary first molar (0.8%). The prevalence of c-shaped canal in the mandibular second molar was higher in women (Female: 23.6%, Male: 16.7%). C-shaped canal in the mandibular second molar was more common in Asian continent compared to other continents. The prevalence of C-shaped canals did not differ significantly in the mandibular second molar on the right and left sides (Right: 21.2%, Left: 23.1%).

Based on the results of this systematic review, the highest prevalence of c-shaped canal was in the mandibular second molar and it was more in Asian continent. Clinicians can consider the possibility of a C-shaped canal on the opposite side if they encounter the presence of a C-shaped canal during root canal therapy on one side. CBCT can be used to obtain sufficient information about the morphology of the root canal to improve the success of the root canal treatment.

The online version contains supplementary material available at 10.1186/s12903-025-06946-8.