title: Endodontic management of a mandibular first molar with four canals in a distal root by using cone-beam computed tomography: a case report.
abstract: BACKGROUND
  Aberrations in the root canal anatomy are clinically challenging for clinicians. Mandibular first molars usually have 2 roots and 3 or 4 canals, but various combinations may exist. A distal root with three canals is rare and its incidence in literature is about 0.2 - 3%. As a diagnostic tool, cone-beam computed tomography (CBCT) may be a better choice for diagnosis of extra roots or canals comparing to conventional radiography.
  
  
  METHODS
  An endodontic management of a mandibular first molar with six canals was performed. CBCT was used to confirm the diagnosis and to understand the morphology of the canals.
  
  
  RESULTS
  Evaluation of the axial and coronal slices of CBCT images confirmed the presence of 2 roots and 6 canals. The distal root had four distinct root canal orifices with two apical foramens, being described as type XIV canal configuration.
  
  
  CONCLUSIONS
  Dentists should be aware of unexpected canal morphology when performing endodontic treatment. The present case demonstrated the use of CBCT in diagnosis and negotiation of extra canals in a mandibular first molar.
authors.affiliation: Department of Endodontics, Faculty of Dentistry, Zahedan University of Medical Sciences, Zahedan Iran.
authors.forename: Hani
authors.initials: H
authors.lastname: Baziar
authors.affiliation: Department of Endodontics, Faculty of Dentistry, Zahedan University of Medical Sciences, Zahedan Iran.
authors.forename: Farzaneh
authors.initials: F
authors.lastname: Daneshvar
authors.affiliation: Department of Oral and Maxillofacial Radiology, Faculty of Dentistry, Zahedan University of Medical Sciences, Zahedan Iran.
authors.forename: Abbas
authors.initials: A
authors.lastname: Mohammadi
authors.affiliation: Dental Research Center, Department of Endodontics, Faculty of Dentistry, Mashhad University of Medical Sciences, Mashhad Iran.
authors.forename: Hamid
authors.initials: H
authors.lastname: Jafarzadeh
keywords: anatomy; cone-beam computed tomography; molar; tooth canal.; tooth root