Department of Conservative Dentistry, Ewha Womans University School of Medicine, Seoul, Korea.
Microscope Center, Department of Conservative Dentistry and Oral Science Research Center, College of Dentistry, Yonsei University, Seoul, Korea.
J Endod. 2018 Jan;44(1):46-50. doi: 10.1016/j.joen.2017.08.005. Epub 2017 Oct 21.
The aim of this study was to determine the morphologic characteristics of mandibular first molars having 2 canals in distal roots. Interorifice distance, buccal bone thickness, and root curvature were evaluated using cone-beam computed tomography images in a Korean population.
In total, 1958 mandibular first molars were evaluated in axial, coronal, sagittal, and paraxial planes. Distal roots having 2 canals were classified according to their root and canal shapes (2 roots, 2 canals [2R2C]; 1 root, 2 canals with 2 apical foramina [1R2C(2-2)]; and 1 root, 2 canals with 1 apical foramen [1R2C(2-1)]). The distances between orifices and the distance from the apex to the buccal bone plate were measured for each root canal shape (2R2C, 1R2C[2-2], and 1R2C[2-1]). The curvature of distolingual (DL) roots was classified according to severity using 3-dimensional reconstructed images, and the direction of curvature was determined. The relationships of these characteristics to sex and side were evaluated.
The prevalences of 2R2C, 1R2C(2-2), and 1R2C(2-1) were 25.89%, 10.32%, and 14.15%, respectively. The distances between distobuccal (DB) and DL orifices were 3.77 ± 0.74 mm for 2R2C, 3.02 ± 0.65 mm for 1R2C(2-2), and 2.44 ± 0.64 mm for 1R2C(2-1). The distances from the buccal plate to the DB canal were 3.84 ± 1.35 mm for 2R2C, 5.33 ± 1.41 mm for 1R2C(2-2), and 5.96 ± 1.63 mm for 1R2C(2-1). The distance from the buccal plate to the DL canal was 9.85 ± 1.46 mm for 2R2C, and 8.28 ± 1.50 mm for 1R2C(2-2). All distances differed significantly according to root canal configurations, and all were greater in men than women (P < .05), except for the DB-DL orifice distance in 1R2C(2-2) and the DB to buccal cortical plate distance in all root configurations (P > .05). No significant difference between the left and right sides was found (P > .05). The prevalence of most severely curved DL roots (type III) was 62.92%, and the direction was commonly toward the buccal side (69.03%).
The prevalence of mandibular first molars having 2 canals in distal roots was more than 50% in a Korean population. Interorifice distances between DB and DL canals and distances from the apex to the buccal cortical plate differed according to root and canal numbers and shapes.
本研究旨在确定韩国人群中具有 2 个远中根管的下颌第一磨牙的形态特征。使用锥形束计算机断层扫描图像评估了根管间距离、颊骨厚度和根弯曲度。
共评估了 1958 颗下颌第一磨牙的轴位、冠状位、矢状位和旁轴位图像。根据根和根管的形状，将具有 2 个根管的远中根分为以下几类（2 个根，2 个根管[2R2C]；1 个根，2 个根管有 2 个根尖孔[1R2C（2-2）]；1 个根，2 个根管有 1 个根尖孔[1R2C（2-1）]）。测量了每个根管形状（2R2C、1R2C[2-2]和 1R2C[2-1]）的根管间距离和根尖至颊骨板的距离。根据三维重建图像的严重程度对远舌（DL）根的弯曲程度进行分类，并确定弯曲方向。评估了这些特征与性别和侧别之间的关系。
2R2C、1R2C（2-2）和 1R2C（2-1）的患病率分别为 25.89%、10.32%和 14.15%。2R2C 的近颊（DB）和远舌（DL）根管之间的距离为 3.77±0.74mm，1R2C（2-2）为 3.02±0.65mm，1R2C（2-1）为 2.44±0.64mm。2R2C 的颊侧骨板至 DB 根管的距离为 3.84±1.35mm，1R2C（2-2）为 5.33±1.41mm，1R2C（2-1）为 5.96±1.63mm。2R2C 的颊侧骨板至 DL 根管的距离为 9.85±1.46mm，1R2C（2-2）为 8.28±1.50mm。所有距离均根据根管配置显著不同，且男性均大于女性（P<.05），除 1R2C（2-2）的 DB-DL 根管间距离和所有根管配置的 DB 至颊骨皮质板距离外（P>.05）。左右侧之间无显著差异（P>.05）。最严重弯曲的 DL 根（III 型）的患病率为 62.92%，通常向颊侧弯曲（69.03%）。
在韩国人群中，下颌第一磨牙远中根具有 2 个根管的患病率超过 50%。近颊和远舌根管之间的根管间距离以及根尖至颊骨皮质板的距离因根和根管的数量和形状而异。
