A cone-beam computed tomography study of C-shaped root canal systems in mandibular second premolars in a Taiwan Chinese subpopulation.

Background/purpose: The purpose of this study is to investigate the prevalence and the morphologic characteristics of the radicular groove and root canal system in human mandibular second premolars with C-shaped root in a Taiwan Chinese subpopulation using cone-beam computed tomographic (CBCT) imaging.

Methods: CBCT images of 580 mandibular second premolars were collected from 317 patients. All of the mandibular second premolars were examined in serial axial sections to identify the presence of any C-shaped root and C-shaped canal systems. The morphologic characteristics of mandibular second premolars with C-shaped roots were studied by performing measurements of serial axial sections.

Results: The prevalence rate of mandibular second premolars with a C-shaped root was 3.45% (20/580 teeth) and the rate of those with a C-shaped canal system was 2.24% (13/580 teeth). It was found that 69% of the radicular grooves were located on the lingual half of the root (9/13 teeth) in mandibular second premolars with a C-shaped canal system. In those teeth with a lingual radicular groove, the main canal was toward the buccal side. Frequently, the first C-shaped canal image was found at the mid-root level. The deepest part of the radicular groove was located at about 2.5 mm apical to the first C-shaped canal image.

Conclusion: There was a 2-3% morphologic variation of the mandibular second premolar with a C-shaped root canal system among the Taiwan Chinese subpopulation investigated in this study. Detailed knowledge of the morphological characteristics of teeth may be valuable when choosing clinical treatments.