Jiangsu Key Laboratory of Oral Diseases, Nanjing Medical University, Nanjing, China; Department of Conservative Dentistry and Endodontics, School of Stomatology, Nanjing Medical University, Nanjing, China.
Central Lab, First People's Hospital of Wujiang District, Suzhou, China.
J Endod. 2017 Dec;43(12):1990-1996. doi: 10.1016/j.joen.2017.06.021. Epub 2017 Oct 9.
The purpose of this study was to investigate the incidence and location of the second mesiobuccal (MB2) root canal of the maxillary first molar and the relationship between the presence of an MB2 canal and the distribution of canal orifices on the pulpal floor with the aid of cone-beam computed tomographic (CBCT) technology.
A total of 1008 maxillary first molars (548 patients) were randomly selected and analyzed through CBCT imaging. The association between the incidence of MB2 canals and potential impacting factors including sex, side, age, and the distribution of the main root canal orifices on the pulpal floor was explored. The interorifice distances (ie, the length of a line between the center point of any 2 orifices) at the pulpal floor level were measured using Mimics 10.01 software (ImageWorks, Materialise, Belgium).
The majority of 3-rooted maxillary first molars showed 2 root canals (85.4%) in the mesiobuccal root. The incidence of MB2 canals had no statistically significant difference between the left and right sides (P > .05) but had a significant association with the patients' sex and age (P < .05). Receiver operating characteristic curve analysis showed a high diagnostic accuracy (the area under the receiver operating characteristic curve = 0.92) of using the distance ratio of the interorifice distance between the main mesiobuccal and the palatal root canal orifices to the interorifice distance between the distobuccal and the palatal root canal orifices to predict the presence of an MB2 canal. A larger distance ratio (>1.26) indicated a highly probable existence of an MB2 canal. In this study, no molar presented an MB2 canal with a distance ratio of less than 1.16, whereas all molars with a ratio greater than 1.37 presented an MB2 canal without exception. A Bland-Altman scatterplot showed great agreement between the distances of the main mesiobuccal and the distobuccal canal orifices and the second mesiobuccal and the distobuccal canal orifices.
Understanding the incidence of MB2 canals and the distribution pattern of canal orifices on the pulpal floor may help clinicians to quickly identify and locate MB2 canals.
本研究旨在借助锥形束 CT（CBCT）技术，调查上颌第一磨牙第二近中颊（MB2）根管的发生率和位置，以及 MB2 根管的存在与牙髓底部主根管口分布之间的关系。
通过 CBCT 成像，随机选择并分析了 1008 颗上颌第一磨牙（548 名患者）。探讨了 MB2 根管的发生率与性别、侧别、年龄等潜在影响因素之间的关系，以及牙髓底部主根管口的分布。使用 Mimics 10.01 软件（比利时 Materialise 的 ImageWorks）测量牙髓底部水平的根管间距离（即任意两个根管口中心点之间的线的长度）。
绝大多数 3 根上颌第一磨牙的近中颊根有 2 个根管（85.4%）。MB2 根管的发生率在左右两侧之间无统计学差异（P>.05），但与患者的性别和年龄有显著关系（P<.05）。受试者工作特征曲线分析显示，使用主近中颊根管和腭根根管口之间的根管间距离与远中颊根管和腭根根管口之间的根管间距离的比值来预测 MB2 根管存在的距离比值具有较高的诊断准确性（受试者工作特征曲线下面积=0.92）。较大的距离比值（>1.26）表明存在 MB2 根管的可能性较大。在本研究中，没有磨牙的 MB2 根管距离比值小于 1.16，而所有比值大于 1.37 的磨牙都无一例外地存在 MB2 根管。Bland-Altman 散点图显示，主近中颊根管和远中颊根管口之间的距离与第二近中颊根管和远中颊根管口之间的距离非常吻合。
了解 MB2 根管的发生率和牙髓底部根管口的分布模式有助于临床医生快速识别和定位 MB2 根管。
