State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) & Key Laboratory of Oral Biomedicine Ministry of Education, School and Hospital of Stomatology, Wuhan University, Wuhan, China.
J Endod. 2010 Nov;36(11):1866-9. doi: 10.1016/j.joen.2010.08.030. Epub 2010 Sep 17.
The purpose of this study was to investigate the three-dimensional (3-D) morphology of isthmuses in the mesial roots of mandibular molars.
One hundred twenty-six extracted mandibular molars including 70 first molars (MFMs) and 56 second molars (MSMs) from a Chinese population were scanned by micro-computed tomography, and the apical 5 mm of the root canals with or without isthmuses was reconstructed with 3D-Doctor software. Each reconstructed isthmus model was assigned to 1 of the following 4 categories: sheet connection, separate, mix, and cannular connection. The length of the isthmus (L(i)) and the distance from the bottom of the isthmus to apex (D(ba)) were measured and analyzed.
The incidence of an isthmus in the apical 5 mm of the mesial roots was 85%. MFMs had more isthmuses with separate type and mixed type, whereas MSMs had more isthmuses with sheet connections. The L(i) and D(ba) in mandibular molars were 2.331 mm and 1.850 mm, respectively.
MFMs present different anatomical features of isthmuses in the apical part of the mesial roots than MSMs.
本研究旨在探讨下颌磨牙近中根峡部的三维（3-D）形态。
本研究从中国人的 126 颗离体下颌磨牙中，选取 70 颗第一磨牙（MFMs）和 56 颗第二磨牙（MSMs），通过微计算机断层扫描（micro-computed tomography）对其进行扫描，并使用 3D-Doctor 软件重建有或无峡部的根尖 5mm 处的根管。将每个重建的峡部模型分为以下 4 类之一：片状连接、分离、混合和管腔连接。测量并分析峡部的长度（L(i)）和峡部底部到根尖的距离（D(ba)）。
在近中根根尖 5mm 处，峡部的发生率为 85%。MFMs 中更常见的峡部类型是分离型和混合型，而 MSMs 中更常见的峡部类型是片状连接型。下颌磨牙的 L(i)和 D(ba)分别为 2.331mm 和 1.850mm。
MFMs 在近中根根尖部的峡部解剖特征与 MSMs 不同。
