Japanese Maxillary First Molar Root Canal Morphology: An Ultrastructural Study Using Micro-Computed Tomography

Abstract

The present study used ultra-high-resolution micro-computed tomography (CT) to clarify the classification of root canal morphologies and the incidence of accessory canals in the maxillary first molar mesiobuccal (MB) root. Aspects of the relationship with root canal reinfection during or after molar endodontic treatment were also investigated. Molar three-dimensional structure, pulp cavity, and accessory canals were examined on micro-CT images of 100 Japanese maxillary first molars from the collection at the Department of Anatomy, Tokyo Dental College. The most common Vertucci’s classification of the main root canal of the Japanese maxillary first molar mesial root canal was Type I, followed by Type V. Accessory canal incidence was 75.0%, which was higher than previously reported; however, the majority of such canals were within the apical 3 mm. Many accessory canals were observed even with the single canals of Type I, suggesting that the existence of accessory canals should always be considered even if diagnostic imaging clearly shows a Type I classification.