Association of root morphology of mandibular second molars on panoramic-like and axial views of cone-beam computed...

Knowledge about the anatomy and morphology of the root canal system is essential for successful surgical and non-surgical root canal treatments. However, precise assessment of the root morphology and anatomy is not often possible on two-dimensional radiographs. This study aimed to investigate the association of root morphology of mandibular second molars on panoramic-like and axial views of cone-beam computed tomography (CBCT).

This cross-sectional study evaluated 1,231 CBCT scans of mandibular second molars obtained between October 2018 and February 2022 that were retrieved from the archives of a private radiology clinic. Panoramic-like images were reconstructed from the CBCT scans. The root morphology of mandibular second molars was classified on panoramic-like images as type 1, 2, 3, 4, or 5. The root pattern on axial CBCT images was classified into three types of single, double and C-shaped. The association of root morphology on panoramic-like and axial CBCT views was analyzed by the Chi-square test and Fisher's exact test at 0.05 level of significance.

Of all, 62.7% of mandibular second molars were type 1; out of which, 97.3% had a double-root pattern on axial CBCT images. Also, 28.6% of them were type 2; of which, 92.6% had a double-root pattern. Moreover, 3.9% were type 3; of which, 47.9% had a C-shaped pattern; 0.9% were type 4, and 45.5% of them showed a single-root pattern; 3.8% were type 5 with 76.6% of them showing a single-root pattern. The prevalence of C-shaped canals was higher in females, and most C-shaped canals had a C3 pattern.

Root morphology on panoramic-like CBCT views had a strong association with the root canal pattern on axial CBCT views. According to the results, mandibular second molars with a type 3 morphology on panoramic-like CBCT images are highly probable to have a C-shaped canal.