Micro-computed tomography analysis of root canal morphology and thickness of crown and root of mandibular incisors in Chinese population

Objectives The aim of this study was to investigate the root canal morphology and the thickness of crown and root of mandibular incisors in a Chinese subpopulation by micro-computed tomography (micro-CT). Methods In total, 208 mandibular incisors were scanned using micro-CT. The anatomical features of the canals (canal configuration, apical constriction, foramen-to-apex distance, accessory canal vertical distribution, and canal geometrical parameters) and the thickness of the crown and root 2/3 were evaluated. Results Three canal categories, labeled as Single (77.88%), Merged (15.87%), and Separated (6.25%), were summarized. The most frequent constriction type in main foramina was single constriction (42.53%). Wide and narrow diameters in a single main foramen were 0.37 +/- 0.14 mm and 0.26 +/- 0.07 mm, respectively. The distance from the anatomical foramen to the physiological foramen and the anatomical apex was 0.49 +/- 0.20 mm and 0.36 +/- 0.28 mm, respectively. During the virtual root-end resection, 97.12% of roots underwent successful resection at the 2-mm level, with the foramina visible on the resection surface. During 2-D cross-sectional analyses, the shape parameters of the root and canal showed significant positive correlation (P < 0.05). The thickest and thinnest walls were the incisal and proximal walls (P < 0.05) of the crown, respectively. The buccal walls were significantly thicker than the lingual walls on the crown (P < 0.05), whereas the lingual walls were thicker on the root 2/3 (P < 0.05). Conclusions This study provides detailed information about the root canal morphology and thickness of the crown and root of mandibular incisors in a Chinese population. An understanding of morphology can benefit endodontic treatment.