title: Frequency of Root Canal Isthmi in Human Permanent Teeth Determined by Cone-beam Computed Tomography.
abstract: BACKGROUND
  This study evaluated the frequency of root canal isthmi (RCIs) in human permanent teeth by using cone-beam computed tomography.
  
  
  METHODS
  A sample of 1400 teeth of 618 patients (394 women; mean age, 43.4 years) was selected. RCIs were detected longitudinally on 0.1-mm/0.1-mm axial slices of cone-beam computed tomography images of roots scanned from the pulp orifice to the apex, and findings were classified into 7 categories according to RCIs beginning and end: (1) both in the cervical third, (2) begin in the cervical third and end in the middle third, (3) begin in the cervical third and end in the apical third, (4) both in the middle third, (5) begin in the middle third and end in the apical third, (6) both in the apical third, or (7) no isthmus. A χ(2) test with Yates correction or the Fisher exact test was used to analyze categorical variables, described as frequencies (%). The Student t test was used to compare quantitative variables.
  
  
  RESULTS
  RCI is a common anatomic structure in human permanent teeth, except in maxillary anterior teeth.
  
  
  CONCLUSIONS
  The higher frequencies of RCIs (87.9%) were found in mandibular first molars. The frequencies of RCIs according to mean age and tooth group were not significantly different (P > .05), except in mandibular central incisors. RCIs were less frequent among older patients.
authors.affiliation: Department of Stomatologic Sciences, Federal University of Goiás, Goiânia, Goiás, Brazil. Electronic address: estrela3@terra.com.br.
authors.forename: Carlos
authors.initials: C
authors.lastname: Estrela
authors.affiliation: Department of Stomatologic Sciences, Federal University of Goiás, Goiânia, Goiás, Brazil.
authors.forename: Luiz Eduardo G
authors.initials: LE
authors.lastname: Rabelo
authors.affiliation: Department of Stomatologic Sciences, Federal University of Goiás, Goiânia, Goiás, Brazil.
authors.forename: João Batista
authors.initials: JB
authors.lastname: de Souza
authors.affiliation: Department of Stomatologic Sciences, Federal University of Goiás, Goiânia, Goiás, Brazil.
authors.forename: Ana Helena G
authors.initials: AH
authors.lastname: Alencar
authors.affiliation: Department of Oral Sciences, University of Cuiabá, Mato Grosso, Brazil.
authors.forename: Cyntia R A
authors.initials: CR
authors.lastname: Estrela
authors.affiliation: Department of Endodontics, University of São Paulo, Ribeirão Preto, São Paulo, Brazil.
authors.forename: Manoel Damião
authors.initials: MD
authors.lastname: Sousa Neto
authors.affiliation: Department of Endodontics, University of São Paulo, Ribeirão Preto, São Paulo, Brazil.
authors.forename: Jesus Djalma
authors.initials: JD
authors.lastname: Pécora
mesh_terms: D000328:Adult; D054893:Cone-Beam Computed Tomography; D003786:Dental Pulp Cavity / Q000033:anatomy & histology* / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D008297:Male; D008334:Mandible; D008963:Molar / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D012390:Root Canal Therapy; D014092:Tooth Root / Q000033:anatomy & histology* / Q000000981:diagnostic imaging*
keywords: Apical periodontitis; cone-beam computed tomography; endodontic failure; root canal anatomy; root canal isthmus