Shigefuji Ryohei, Serikawa Masamitsu, Usami Akinobu
Department of Morphological Biology, Ohu University School of Dentistry, Koriyama, Japan.
Anat Cell Biol. 2022 Jun 30;55(2):155-160. doi: 10.5115/acb.22.050.
The mandibular second molars show various morphological features in the roots and root canal, and a guttershaped root (GSR) caused by fusion of the mesial and distal roots is frequently encountered. In this study the number of the roots associated with mandibular second molars were observed using dental cone-beam computed tomography (CBCT). For those with a GSR, determination of root morphology and root canal classification were performed. CBCT image data from 173 Japanese mandibular second molars were obtained. Using sliced images, the number of the roots and root morphology were determined. In cases with a GSR, the ratio for the fused roots was determined and root canal morphology features were classified. A GSR was found in 61 (35.3%), with greater prevalence in females. In addition, the overall ratio of the fused part to root thickness in those with a GSR was 48.7%, with no significant difference related to sex. Furthermore, a C-shaped root canal morphology was commonly observed in both males and females with a GSR. In the present cohort examined in Japanese, most of the mandibular second molar were found to have two roots, with a GSR noted in 35.5%. While a GSR was more often observed in females, a C-shaped root canal was the most common root canal morphology in both sexs. It is considered that assessment using CBCT findings is helpful for precise determination of root canal morphology and presence of a GSR in mandibular second molars.
下颌第二磨牙在牙根和根管方面呈现出多种形态特征，并且常常会遇到由近中根和远中根融合导致的沟形根（GSR）。在本研究中，使用牙科锥形束计算机断层扫描（CBCT）观察与下颌第二磨牙相关的牙根数量。对于存在GSR的情况，进行牙根形态和根管分类的确定。获取了173颗日本下颌第二磨牙的CBCT图像数据。利用断层图像确定牙根数量和牙根形态。对于存在GSR的病例，确定融合牙根的比例并对根管形态特征进行分类。发现61颗（35.3%）存在GSR，女性中的患病率更高。此外，存在GSR者融合部分与牙根厚度的总体比例为48.7%，与性别无关，无显著差异。此外，在存在GSR的男性和女性中均常见C形根管形态。在本次对日本人的队列研究中，发现大多数下颌第二磨牙有两个牙根，35.5%存在GSR。虽然GSR在女性中更常被观察到，但C形根管是两性中最常见的根管形态。认为利用CBCT检查结果进行评估有助于精确确定下颌第二磨牙的根管形态和GSR的存在情况。
