title: Micro-computed tomographic analysis of the root canal morphology of the distal root of mandibular first molar.
abstract: BACKGROUND
  The aim of this study was to evaluate the morphologic aspects of the root canal anatomy of the distal root of a mandibular first molar using micro-computed tomographic analysis.
  
  
  METHODS
  One-hundred distal roots of mandibular first molars were scanned using a micro-computed tomographic device at an isotropic resolution of 19.6 μm. The percentage frequency distribution of the morphologic configuration of the root canal was performed according to the Vertucci classification system. Two-dimensional parameters (area, perimeter, roundness, aspect ratio, and major and minor diameters) and the cross-sectional shape of the root canal were analyzed in the apical third at every 1-mm interval from the main apical foramen in roots presenting Vertucci types I and II configurations (n = 79). Data were statistically compared using the Kruskal-Wallis and Dunn tests with a significance level set at 5%.
  
  
  RESULTS
  Seventy-six percent of the distal roots had a single root canal. Two, three, and four canals were found in 13%, 8%, and 3% of the sample, respectively. In 13 specimens, the configuration of the root canal did not fit into Vertucci's classification. Overall, 2-dimensional parameter values significantly increased at the 3-mm level (P < .05). The prevalence of oval canals was higher at the 1-mm level and decreased at the 5-mm level in which long oval and flattened canals were more prevalent.
  
  
  CONCLUSIONS
  The distal roots of the mandibular first molars showed a high prevalence of single root canals. The prevalence of long oval and flattened canals increased in the coronal direction. In 13% of the samples, canal configurations that were not included in Vertucci's configuration system were found.
authors.affiliation: Department of Dentistry, Endodontics and Dental Materials, Bauru School of Dentistry, University of São Paulo, University of São Paulo, São Paulo, Brazil.
authors.forename: Carolina
authors.initials: C
authors.lastname: Filpo-Perez
authors.affiliation: Department of Dentistry, Endodontics and Dental Materials, Bauru School of Dentistry, University of São Paulo, University of São Paulo, São Paulo, Brazil.
authors.forename: Clovis Monteiro
authors.initials: CM
authors.lastname: Bramante
authors.affiliation: Department of Dentistry, Endodontics and Dental Materials, Bauru School of Dentistry, University of São Paulo, University of São Paulo, São Paulo, Brazil.
authors.forename: Marcelo Haas
authors.initials: MH
authors.lastname: Villas-Boas
authors.affiliation: Department of Dentistry, Endodontics and Dental Materials, Bauru School of Dentistry, University of São Paulo, University of São Paulo, São Paulo, Brazil.
authors.forename: Marco Antonio
authors.initials: MA
authors.lastname: Húngaro Duarte
authors.affiliation: Department of Restorative Dentistry, Dental School of Ribeirão Preto, University of São Paulo, São Paulo, Brazil.
authors.forename: Marco Aurélio
authors.initials: MA
authors.lastname: Versiani
authors.affiliation: Department of Dentistry, Endodontics and Dental Materials, Bauru School of Dentistry, University of São Paulo, University of São Paulo, São Paulo, Brazil. Electronic address: ronaldordinola@usp.br.
authors.forename: Ronald
authors.initials: R
authors.lastname: Ordinola-Zapata
mesh_terms: D003786:Dental Pulp Cavity / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods; D008334:Mandible / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D008963:Molar / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D012390:Root Canal Therapy / Q000379:methods; D019227:Tooth Apex / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D014092:Tooth Root / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D055114:X-Ray Microtomography
keywords: Dental anatomy; mandibular molars; micro–computed tomography; root canal anatomy