title: Morphometric study of the apical anatomy of C-shaped root canal systems in mandibular second molars.
abstract: OBJECTIVE
  To investigate the apical anatomy of C-shaped canal systems in mandibular second molars by micro-computerized tomography (microCT) and stereomicroscopy.
  
  
  METHODS
  Forty-four permanent mandibular second molars with a C-shaped root canal systems from a native Chinese population were scanned at 100 microm intervals by microCT at a resolution of 30 x 30 microm. The apical 5 mm of each tooth was reconstructed three-dimensionally for visualization and classification of the canal configuration using Vertucci's criteria. The main and auxiliary (accessory) foramina were examined under a stereomicroscope.
  
  
  RESULTS
  Type IV and VIII canal configurations were most often found in the apical 5 mm of these canal systems. The prevalence of accessory canals, lateral canals, inter-canal communications and apical delta were 41%, 25%, 27% and 11%, respectively. Approximately 80% of C-shaped canals had 1-3 apical foramina; the prevalence of accessory foramina was about 48%. The mean distance between the main foramen and the anatomic root apex was 0.84 mm, and that between the accessory foramen and the apex was 1.61 mm. The mean (shortest and longest) diameters of major and accessory foramina were 0.19 - 0.32 mm and 0.07 - 0.10 mm, with a mean form factor of 0.73 and 0.82, respectively.
  
  
  CONCLUSIONS
  The apical anatomy of C-shaped root canal systems in mandibular second molars is extremely complex with many anatomical variations.
authors.affiliation: Family Dentistry & Endodontics, Faculty of Dentistry, University of Hong Kong, Hong Kong SAR.
authors.forename: G S P
authors.initials: GS
authors.lastname: Cheung
authors.forename: J
authors.initials: J
authors.lastname: Yang
authors.forename: B
authors.initials: B
authors.lastname: Fan
mesh_terms: D044466:Asian People; D003786:Dental Pulp Cavity / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D006801:Humans; D021621:Imaging, Three-Dimensional; D008334:Mandible; D008963:Molar / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D014057:Tomography, X-Ray Computed; D019227:Tooth Apex / Q000033:anatomy & histology* / Q000000981:diagnostic imaging