Microendodontics: identification and treatment of MBII system.

Endodontically, the maxillary first molar is one of the most misunderstood teeth and presents a variety of considerations for the treating practitioner. Clinically, the mesiobuccal root contains a second root canal system that can be identified and treated more than 75 percent of the time. The thorough clinician must assume all maxillary first molars have four canals until proven otherwise.