Location of Canal Isthmus and Accessory Canals in the Mesiobuccal Root of Maxillary First Permanent Molars

Background: Failure in surgical endodontics may be caused by many factors. Failure is commonly due to improper preparation for the root-end filling and a lack of seal of the resected root end. The aim of this study was to investigate the morphology of resected mesiobuccal (MB) root ends of maxillary first molars and to evaluate the location of the canal isthmus and accessory canals between the MB canals.