Rare 3-2-1 Root Canal Configuration With Three Mesiobuccal Canals Identified in Maxillary First Molar: Case Report
A recent case reports an ultra-rare "3-2-1" mesiobuccal root canal configuration in the maxillary first molar of a 14-year-old patient. Found in just 0.1% of cases, this is the first documented third mesiobuccal canal (MB3) in the Indian population.
These findings of the case report were published in the Indian Journal of Dental Science in May 2026 by Dr. Naveena Veeramalai and colleagues at Sree Mookambika Institute of Dental Sciences.
Clinical Case Overview
A 14-year-old female presented with food impaction in her upper left back tooth during chewing, without pain. Clinical examination revealed deep dentinal caries in tooth 26 (FDI system), tender to percussion. Electric pulp testing indicated pulp vitality. Radiographs showed radiolucency approaching the pulp with periapical periodontal ligament space widening. Diagnosis confirmed dental caries, asymptomatic irreversible pulpitis, and symptomatic apical periodontitis, requiring root canal therapy.
Following informed consent, local anesthesia (2% lidocaine with 1:80,000 adrenaline) was administered under rubber dam isolation. Access opening was made using a TF-12 tapered fissure bur and refined with an EndoZ bur. Under dental operating microscope magnification and ultrasonic assistance, five orifices were located using #10 K-files: MB1, MB2, MB3, distobuccal, and palatal. Orifices were enlarged using a ProTaper Gold Sx file. Working length radiographically confirmed a 3-2-1 configuration, originating as three orifices coronally, joining into two canals in the middle third, and exiting as one canal apically.
Preparation utilized ProTaper Gold instruments up to size #F3 in MB1 and distobuccal canals, #F1 in MB2 and MB3, and #F4 in the palatal canal. Canals were disinfected with 3% sodium hypochlorite, 17% EDTA, and saline solutions agitated sonically with the Endoactivator. Canals were dried and obturated with Sealapex sealer and gutta-percha via single-cone technique, with lateral condensation in the palatal root. Resin-modified glass ionomer cement was placed as an intra-orifice barrier before composite restoration. Postoperative cone-beam computed tomography confirmed complete obturation and verified 3-2-1 mesiobuccal morphology alongside Vertucci Type I configurations in distobuccal and palatal roots.
Anatomical Significance and Clinical Implications
The report highlights operating microscopes, ultrasonics, and CBCT imaging in revealing atypical root canal anatomy. Younger patients present broader canal dimensions, aiding extra canal detection before calcification. Anatomical knowledge and advanced diagnostic technology are essential to prevent missed canals and treatment failure.
Reference
Veeramalai, N., Nair, R. S., Christopher, S. R., & Ravi, V. V. (2026). Incidence of an uncommon canal configuration of mesiobuccal root with MB3 canal in the maxillary first molar in Indian population. Indian Journal of Dental Science.
