Hamadan University of Medical Sciences Avicenna Journal of Dental Research 2423-7582 10 1 2018 03 01 A Successful Root Canal Therapy of a Maxillary First Molar With 3 Separate Root Canals in the Mesiobuccal Root: Case Report 31 34 10.34172/ajdr.2018.07 EN Hamed Karkehabadi https://orcid.org/0000-0002-1296-7361 Masoumeh Ramezani Hossein Samiei Journal Article 10.34172/ajdr.2018.07 2018 02 01 2018 03 05 Introduction: An important issue in treatment planning and endodontic treatment is to deal with sophisticated internal dental morphology. Deviations from normal anatomy in maxillary molars are usually related to the number of canals in mesiobuccal root. Although unusual anatomy is not uncommon in maxillary molars, the occurrence of 3 separate canals with distinct orifices and apical foramina (as we see in this case) is extremely rare. Getting familiar with this unusual anatomy helps clinicians to treat patients more efficiently with less chance of failure. Case Presentation: This case report describes a successful endodontic management of an uncommon variation of the maxillary first molar with a third mesiobuccal canal. The tooth had a deep carious lesion and the pulp was irreversibly damaged causing pain on the left side of the face. The periodontium was normal. The tooth received root canal treatment and 400 mg ibuprofen was prescribed every 6 hours for 2 to 3 days. The patient remained asymptomatic and the 3-month follow-up radiograph revealed normal periodontium. Conclusions: Inability to identify and treat additional canals that are very common in the MB root of maxillary first molar could lead to treatment failure.