two symmetrical maxillary first molars with two disto-buccal root canals

introduction: this article describes the diagnosis and treatment of two symmetrical maxillary first molars with two canals in their distobuccal roots. a 32-year-old female had an emergency treatment because of the pain in tooth #16. on the second visit after accessing the pulp chamber and detecting three major canals (mb, db, and p) and exploring the 4th canal (mb 2 ), we noted that there was a 5 th canal in the distobuccal root. also, necrosis was found in the same patient after examining the tooth #26 which was severely decayed. then after preparing the access cavity, the same order of orifices was found in tooth #16. an electronic apex locator was utilized to ensure that a perforation of the pulpal floor had not occurred. working films confirmed the presence of an additional canal in distobuccal root.