title: Three root canals in the mesiobuccal root of maxillary molars: case reports and literature review.
abstract: BACKGROUND
  The knowledge of root canal anatomy is essential to ensure a successful outcome of surgical and nonsurgical root canal treatment. The aims of this article were to present 2 cases of maxillary molars with 3 mesiobuccal root canals and to review the available literature on this anatomic variation.
  
  
  METHODS
  The first case described a nonsurgical root canal treatment of tooth #16 in a 29-year-old man with the aid of a dental operating microscope. In the second case, an extracted maxillary right first molar was scanned by a micro-computed tomographic system and reconstructed 3-dimensionally using modeling software.
  
  
  RESULTS
  In both cases, the mesiobuccal root had 3 canals (type 3-2 in case I and type 3-3 in case II), whereas the distobuccal and palatal roots had a single canal. The literature review showed that the overall incidence of 3-canaled mesiobuccal roots in maxillary molars ranged from 1.3%-2.4% and that the most common root canal configuration was type 3-2.
  
  
  CONCLUSIONS
  Clinicians should always anticipate the presence of extra canals in maxillary molars and use all the available tools to locate and treat these.
authors.affiliation: Restorative Dentistry Department, Riyadh Colleges of Dentistry and Pharmacy, Riyadh, Kingdom of Saudi Arabia. Electronic address: ibrahimali79@yahoo.com.
authors.forename: Ibrahim Ali
authors.initials: IA
authors.lastname: Ahmad
authors.affiliation: Clinic for Preventive Dentistry, Periodontology and Cariology, University Dental Center, University of Zurich, Zurich, Switzerland.
authors.forename: Anas
authors.initials: A
authors.lastname: Al-Jadaa
mesh_terms: D000328:Adult; D063405:Anatomic Variation; D003786:Dental Pulp Cavity / Q000033:anatomy & histology*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D021621:Imaging, Three-Dimensional / Q000379:methods; D008297:Male; D008437:Maxilla; D008853:Microscopy / Q000379:methods; D008963:Molar / Q000033:anatomy & histology*; D010482:Periapical Abscess / Q000628:therapy; D012390:Root Canal Therapy / Q000379:methods; D014092:Tooth Root / Q000033:anatomy & histology*; D055114:X-Ray Microtomography / Q000379:methods
keywords: Anatomic variation; dental operating microscope; maxillary molars; mesiobuccal root; micro–computed tomography; root canal system