The lower second molar mostly has a C configuration and it is important to know the internal anatomy and classification to have a better clinical approach, so the objective was to evaluate the prevalence and types of C-shaped canals in permanent mandibular second molars by using cone beam computed tomography (CBCT).. Materials and Methods: 150 CTHC images of mandibular second molars were used. The following was recorded: sex, presence of C-shaped canal, location, morphology and type of C configuration according to Fan’s classification, which is divided into C1, C2, C3 (c and d), C4 and C5. The chi- square test was used to analyze the differences between groups (p˂0.05, considered a statistically significant difference). Results: Of the 300 teeth evaluated, 12.6% had C-shaped canals. There were no statistically significant differences between C-shaped canals and sex. This configuration...