Assessment of Ramifications in the Apical Region of Root Canals: A Micro-CT Study in a Brazilian Population

Abstract The present study used microcomputed tomography (micro-CT) images to assess the prevalence, number, and location of apical ramifications (ARs) in the root canals of different dental groups in a Brazilian population. Three hundred and sixty-seven extracted human teeth, totaling 475 roots, were scanned by micro-CT at 19.6 µm spatial resolution. The obtained images were evaluated by two observers in consensus, and a descriptive analysis was performed to verify the prevalence, number, and location of ARs in each dental group. Chi-square test was used to compare the prevalence of ARs in different types of roots, and one-way analysis of variance compared the number of ARs in the apical 1 mm, 2 mm, and 3 mm of the root. Significance level was established at 5% (α=0.05). ARs were present in 253 (53.3%) of the 475 roots evaluated. A total of 607 ARs were detected, with the vast majority (530) located at one and two millimeters from the main foramen. The highest prevalence of ARs was observed in maxillary canines (65%); maxillary premolars - single-rooted (83.3%), buccal root (80%), and palatine root (73.3%); mandibular premolars (64.2%); mesiobuccal root of maxillary molars (76.6%); and mesial root of mandibular molars (66.6%). For the Brazilian population, most of the ARs are located in the apical 1 and 2 mm of the root, with greater prevalence in the posterior teeth and maxillary canines. These findings suggest the need for additional attention while planning endodontic treatments, including strategies to effectively clean and fill the apical region.

摘要 本研究采用显微计算机断层扫描（microcomputed tomography, micro-CT）影像，评估巴西人群不同牙组根管内根尖分歧（apical ramifications, ARs）的发生率、数量及分布位置。本研究共纳入367颗拔除的人类牙齿，总计475个牙根，以19.6 μm的空间分辨率进行显微CT扫描。由2名阅片者采用一致性阅片方式对所得影像进行评估，并开展描述性分析，以明确各牙组根尖分歧的发生率、数量及分布位置。采用卡方检验比较不同类型牙根的根尖分歧发生率，采用单因素方差分析比较牙根根尖1 mm、2 mm及3 mm区域内的根尖分歧数量。本研究设定显著性水平为5%（α=0.05）。在所评估的475个牙根中，253个（53.3%）存在根尖分歧。共计检出607个根尖分歧，其中绝大多数（530个）位于距主根尖孔1 mm和2 mm的区域。根尖分歧发生率最高的牙组包括：上颌尖牙（65%）、单根型上颌前磨牙（83.3%）、颊根（80%）及腭根（73.3%）、下颌前磨牙（64.2%）、上颌磨牙近颊根（76.6%）以及下颌磨牙近中根（66.6%）。针对巴西人群的研究结果显示，多数根尖分歧分布于牙根根尖1 mm与2 mm区域，在后牙及上颌尖牙中发生率更高。本研究结果提示，在制定牙髓治疗方案时需予以额外关注，包括采用有效策略对根尖区域进行清洁与充填。