Root canal anatomy variations present a constant challenge in successful diagnosis and endodontic treatment, especially the multirooted teeth. The most challenging root for endodontic treatment at the level of location, shaping, avoidance of iatrogenic events, and obturation is the fourth (MB2) canal of the upper first molars. Maxillary first molar is the most commonly treated tooth yet with the highest endodontic failure rate because of undetected canals, especially the mesiobuccal second canal (MB2).
In this case, MB2 was successfully detected, shaped and cleaned. All four canals were ready for root filling (obturation).