Root canal systems in mandibular first premolars with C-shaped root configurations. Part I: Microcomputed tomography mapping of the radicular groove and associated root canal cross-sections.

The purpose of this study was to investigate the morphology of the radicular grooves and root canal cross-sections in mandibular first premolars that exhibit a C-shaped root. Eighty-six mandibular first premolars with C-shaped roots were scanned from the coronal to anatomical apex using microCT80. The location, length, and depth of the radicular grooves were measured. The cross-sectional morphology of root canal systems was evaluated at 11 levels. Results were subject to the Kruskal-Wallis test. Of the 86 C-shaped roots, a total of 93 radicular grooves were noted. Most of the grooves (78.5%) were located on the mesiolingual surface of the root. The C-shaped canal could vary considerably in shape at different levels, and the incidence of two canals at the middle and apical was 21% and 80%, respectively. This study shows that radicular grooves may present relevant morphologic variations in the root canal system when the C-shaped root is present.