Root and root canal variations of the human maxillary and mandibular third molars in a Chinese population: A micro–computed tomographic study

•The human third molars were examined by micro-CT basing on large sample size.•Odontometric analysis was conducted to measure the length, volume and root surface area.•The root canal systems of third molars exhibited broad spectrum of anatomic variations.•In most of cases, the degree of the canal differentiation was at a low level.•The most complicated root canal system were in the single-rooted maxillary molars. To investigate the anatomical variations of the root and root canal configuration of the human third molars. A total of 130 maxillary and 130 mandibular third molars were collected from a native Chinese population. All teeth were scanned by micro–computed tomography. After 3D reconstruction, the root and canal morphology of each tooth was examined both qualitatively and quantitatively. For maxillary molars, a single fused root (67 cases, 51.5%) and a single root canal system (64 cases, 49.2%) was most common root/canal form; the typical three-rooted molars were detected only in 33 cases (25.4%), and the secondary MB canals were detected only in 9 molars (6.9%). For mandibular molars, 62 teeth were single-rooted (47.7%) and 42 had a single root canal system (32.3%); 20 singled-rooted and 60 double-rooted molars exhibited independent mesial and distal root canal systems (61.5%), and the type 1-1 canal was the most common configuration for mesial (57 cases) and distal (81 cases) root canal systems. C-shaped canals were detected in 11 maxillary and 36 mandibular single-rooted molars. The mean root surface area, root and crown volume of mandibular third molars were significantly higher than the maxillary third molars (P