Prevalence and Morphology of C-Shaped Canals in Mandibular Second Molars: A Cross-Sectional Cone Beam Computed Tomography Study in an Ecuadorian Population

Background/Objectives: C-shaped canals represent a challenge in endodontic procedures. The present study aimed to investigate the prevalence and characteristics of C-shaped canals in mandibular second molars in Guayaquil, Ecuador. Methods: CBCT records from two radiology centers were examined (2020–2022). A total of 400 CBCT scans (800 mandibular second molars) were analyzed using Fan’s classification. Data on the presence or absence of C-shaped canals, gender, and bilateral occurrence were collected. Statistical analysis included the test for differences in proportions and the chi-squared test to assess the significance of correlations between variables. Results: C-shaped canals were found in 28% of mandibular second molars, affecting 33.75% of the patient sample. The prevalence was significantly higher in females (42.9%) compared to males (20.4%). Bilateral occurrences were observed in 63% of affected patients. Morphologic variability was pronounced, with Fan C1 and C4 dominating in the coronal and apical thirds, respectively, while a shift toward Fan C2 and C3 was observed in the middle third. Only 19.2% of the teeth maintained a consistent morphology. Conclusions: C-shaped canals were found in 28% of mandibular second molars and occurred predominantly in females. Notably, most cases were bilateral, highlighting the importance of effectively adapting endodontic techniques to treat this unique anatomical variation. Further research into genetic and environmental influences could deepen our understanding and help develop refined diagnostic and therapeutic strategies.