Root Canal Morphology and Configuration of 179 Maxillary First Molars by Means of Micro-computed Tomography: An Ex Vivo Study

Introduction: The objective of this study was to propose a root canal configuration description method and to investigate the root canal system morphology of the maxillary first molar by means of micro computed tomographic imaging. Methods: The root canal configuration, foramina, and accessory canal frequency of 179 maxillary first molars were investigated by means of micro computed tomographic imaging and 3-dimensional software imaging. The root canal configuration and main foramina number are described from coronal to apical with a 4-digit system. Results: The most frequent root canal configurations were 1-1-1/1 (45.8%), 2-2-2/2 (25.1%) and 2-2-1/1 (10.1%) in mesiobuccal roots and 1-1-1/1 in distobuccal (97.2%) and palatal (98.9%) roots. The first mesiobuccal (MB1) root canal had 1 accessory canal in 26.3% of the teeth, the distobuccal root canal had 12.3%, and the palatal root canal had 9.5%; in the second mesiobuccal root canal, there was rarely 1 accessory canal. There was 1 accessory canal in 26.3%, 12.3%, and 9.5% in the MB1, distobuccal, and palatal root canals, respectively. The MB1; distobuccal, and palatal root canals had 1 main foramen. The MB2 had 1 main foramen in 39.0% of the teeth and no main foramen in 61.0%. Conclusions: The root canal configuration of maxillary first molars is quite diversified. Contrary to our expectations in this research, the mesiobuccal root has predominantly 1 root canal entrance and only 1 main foramen. Anatomic variations including connecting and accessory canals occur in any third of root.