<b>Morphological Variations of the Root Canal System in C-shaped Roots of the Mandibular Second Molar in a Japanese Population </b>

Prevalence of C-shaped canals and three-rooted mandibular molars in the Iranian population by using cone-beam computed tomography

OBJECTIVES

This study aimed to evaluate the prevalence of C-shaped canals and three-rooted mandibular molars in the Iranian population using cone-beam computed tomography (CBCT).

MATERIALS AND METHODS

This study evaluated mandibular teeth on 292 CBCT scans of patients referred to the Department of Radiology, Faculty of Dentistry, Islamic Azad University, Isfahan, Iran. All CBCT scans were obtained with the same three-dimensional CBCT scanner, and sections were reconstructed in all three planes (sagittal, axial, and coronal) with 1 mm slice thickness. A total of 291,402, and 200 first, second, and third molars, respectively, were evaluated. Data were analyzed using SPSS software (version 26.0).

RESULTS

Of 291 mandibular first molars, 0.7% were single-rooted, 96.6% were two-rooted, and 2.7% were three-rooted. The prevalence of C-shaped canals was 1.7% in mandibular first molars. Of 402 mandibular second molars, 8.5% were single-rooted, 90.5% were two-rooted, and 1% were three-rooted. The prevalence of C-shaped canals was 2% in mandibular second molars. Of 200 mandibular third molars, 21.5% were single-rooted, 77.5% were two-rooted, and 1% were three-rooted. The prevalence of C-shaped canals was 2% in mandibular third molars.

CONCLUSION

In the present study, the majority of mandibular molars were two-rooted, and three-rooted mandibular molars were less common. The third and second mandibular molars both had an increased prevalence of C-shaped canals. Mandibular first molars had the highest prevalence of three-rooted molars.

Observation of mandibular second molar roots and root canal morphology using dental cone-beam computed tomography

The mandibular second molars show various morphological features in the roots and root canal, and a gutter-shaped root (GSR) caused by fusion of the mesial and distal roots is frequently encountered. In this study the number of the roots associated with mandibular second molars were observed using dental cone-beam computed tomography (CBCT). For those with a GSR, determination of root morphology and root canal classification were performed. CBCT image data from 173 Japanese mandibular second molars were obtained. Using sliced images, the number of the roots and root morphology were determined. In cases with a GSR, the ratio for the fused roots was determined and root canal morphology features were classified. A GSR was found in 61 (35.3%), with greater prevalence in females. In addition, the overall ratio of the fused part to root thickness in those with a GSR was 48.7%, with no significant difference related to sex. Furthermore, a C-shaped root canal morphology was commonly observed in both males and females with a GSR. In the present cohort examined in Japanese, most of the mandibular second molar were found to have two roots, with a GSR noted in 35.5%. While a GSR was more often observed in females, a C-shaped root canal was the most common root canal morphology in both sexs. It is considered that assessment using CBCT findings is helpful for precise determination of root canal morphology and presence of a GSR in mandibular second molars.