Root Canal Systems in Mandibular First Premolars with C-shaped Root

Objectives:to investigate the morphology of the radicular grooves and root canal cross sections in mandibular first premolars that exhibit a C-shaped root using micro-computed tomography. Methods:86 mandibular first premolars with C-shaped roots were selected from 358 mandibular first premolars in a Chinese population and scanned from the coronal to anatomical apex using µCT80. The location, length and depth of the radicular grooves were measured. The cross-sectional morphology of root canal systems were evaluated at 11 levels. Results were subject to the Kruskal-Wallis test. Results:Of the 86 C-shaped roots, a total of 93 radicular grooves were noted. Most of grooves (78.5%) were located on mesial lingual surface of the root. The C-shaped canal could be seen to vary considerably in shape at different levels(p<0.005), and the incidence of double canals at the middle and apical was 21% and 80%, respectively. Conclusion:This study demonstrates that radicular grooves of mandibular first premolars may present relevant morphological variations in the root canal system when the C-shaped root is present. This study was supported by the National Natural Science Foundation of China (Grant No.30572042) and the Key Technologies R&D Programme of Hubei Province,China (Grant No.2007AA302B06).