Micro–computed Tomographic Evaluation of the Prevalence, Distribution, and Morphologic Features of Accessory Canals in Chinese Permanent Teeth

Introduction: The present study used high-resolution micro–computed tomographic imaging to investigate the prevalence, distribution, and morphologic features of accessory canals (ACs) in the Chinese population. Methods: Scanning was performed on 1400 extracted permanent teeth using 15-μm resolution. The prevalence and distribution of the ACs in those teeth were analyzed. The number of ACs was calculated based on the following morphologic features: patent ACs without branching, obstructed ACs without branching, and branched ACs. Patent ACs were virtually segmented for measurements of their length and tortuosity. Results: ACs were identified in 735 teeth (401 upper and 334 lower teeth). The incidences of ACs in the mesiobuccal and mesial roots were higher in the upper and lower molars. Of the 1611 ACs detected, 1182 were patent ACs without branching, 291 were obstructed ACs without branching, and 138 were branched ACs. In those branched ACs, 114 were type 1-2, 20 were type 2-1, and 4 were type 1-2-1. Most ACs were located in the apical third of the canal space (86.5%), with a median length of 880.9 μm. The length of ACs in the apical third was significantly shorter than those in the middle and coronal thirds of the canal space (P <.05). Conclusions: For the Chinese population, most ACs are located in the apical third, with lengths that are considerably shorter than those in the coronal and middle thirds of the canal space. Because ACs are more prevalent in premolars and molars, attention should be paid to their morphologic features during root canal treatment.