Prevalence evaluation and classification of bifid mandibular canals in CBCT exams in different facial types

Abstract Objetive The aim of this study is to establish the prevalence and classification of mandibular canal alterations using cone beam computed tomography (CBCT) in different facial types. This research was submitted and approved by the research ethics committee, registration number 2.065.839. Material and method The sample consisted of 90 CBCTs from the São Leopoldo Mandic Dental School database (Campinas-SP), divided into three groups according to brachycephalic, dolichocephalic and mesocephalic facial types. Result Of the 90 patients, 23 presented bifid mandible canals (25.6%), of which 60.9% were in males and 39.1% in females. In 39.1%, the canal bifurcation occurred towards the retromolar region (class D), 21.7% had a trajectory to an alveolar or upper direction (class C) and 13.1% were classified as C-E. For the remaining classifications (A, E, F and A-E), the frequencies were in the range of 8.7% to 4.3%. None of the 23 cases of mandibular canal bifurcation was classified as B (mesial direction). Conclusion According to the results obtained from this study, the prevalence of bifid mandibular canals was found to be 25.6%, with class D being the most prevalent for the retromolar region and the highest occurrence was unilaterally on the left side. When evaluating the occurrence of bifid mandibular canals in relation to facial types, brachycephalic patients were the most affected.

摘要：研究目的
本研究旨在借助锥形束计算机断层扫描（cone beam computed tomography, CBCT）明确不同面型人群下颌管改变的患病率与分类情况。本研究已通过研究伦理委员会审核并获批，审批登记号为2.065.839。

材料与方法
研究样本取自巴西圣保罗州坎皮纳斯市圣莱奥波尔多·曼迪克牙科学院数据库中的90例CBCT影像，按短颅面型（brachycephalic）、长颅面型（dolichocephalic）及中颅面型（mesocephalic）分为三组。

结果
90例患者中，23例存在下颌管分叉（占比25.6%），其中男性占60.9%，女性占39.1%。39.1%的分叉发生于磨牙后区（D型），21.7%的分叉走向为牙槽或上方（C型），13.1%被归类为C-E型；其余分类（A、E、F及A-E型）的占比介于4.3%至8.7%之间。23例下颌管分叉病例中无1例被归类为B型（近中走向）。

结论
基于本研究结果，下颌管分叉的患病率为25.6%；其中以磨牙后区的D型最为常见，且分叉多单侧发生于左侧。在分析不同面型人群的下颌管分叉发生率时，短颅面型患者的受累比例最高。