Department of Endodontics, Case Western Reserve University School of Dental Medicine, Cleveland, Ohio.
Department of Endodontics, Case Western Reserve University School of Dental Medicine, Cleveland, Ohio.
J Endod. 2017 Nov;43(11):1797-1801. doi: 10.1016/j.joen.2017.07.003. Epub 2017 Aug 30.
The present study aimed to determine the incidence and anatomic variation of the middle mesial (MM) canal in mandibular permanent first molars using cone-beam computed tomographic imaging and to evaluate the association between the presence of MM canals and anatomic landmarks of the pulp chamber floor in the mesial root.
In this in vivo cross-sectional study, 210 CBCT scans of mandibular fist molars from 210 patients were included. CBCT scans were evaluated in 3 sections, and the following data were collected for further analysis: identification of the MM canal, the distance between the mesiobuccal (MB) and mesiolingual (ML) orifices, the presence of any isthmus between the MB and ML orifices, and the MB and ML root canal system (RCS) configurations. Binary logistic regression was performed to assess the effect of pulp floor anatomic characteristics as an independent variable on the outcome variable (the presence of an MM canal).
The overall prevalence of the identification of an MM canal regardless of age was 14.7%. Mandibular first molars with an isthmus between the MB and ML RCS configurations were almost 5 times more likely to show an MM canal (P < .05, odds ratio [OR] = 4.9). The MB-ML intraorifice distance was inversely associated with the presence of an MM canal (P < .05, OR = 0.73). Patients less than 42 years old were 4 times more likely to have an MM canal in their CBCT scans compared with patients older than 42 years old (P < .05, OR = 3.9).
The suggested anatomic landmarks of the pulp chamber floor could act as a reliable predictive factor for the presence of an MM canal. This knowledge of anatomic clues may serve to better direct endodontists in locating an MM canal, which could prevent excessive removal of tooth structures.
本研究旨在通过锥形束 CT 成像确定下颌恒第一磨牙的中间近中（MM）管的发生率和解剖变异，并评估近中根管牙髓室底解剖标志与 MM 管存在的相关性。
本研究为前瞻性病例研究，共纳入 210 名患者的 210 例下颌第一磨牙的锥形束 CT 扫描。将 CBCT 扫描分为 3 个部分进行评估，并收集以下数据进行进一步分析：MM 管的识别、近颊（MB）和近舌（ML）孔之间的距离、MB 和 ML 孔之间是否存在任何峡部，以及 MB 和 ML 根管系统（RCS）的配置。采用二元逻辑回归分析评估牙髓室底解剖特征作为独立变量对结局变量（存在 MM 管）的影响。
无论年龄大小，识别 MM 管的总体发生率为 14.7%。MB 和 ML RCS 之间有峡部的下颌第一磨牙显示 MM 管的可能性几乎是没有峡部的 5 倍（P<.05，优势比[OR]=4.9）。MB-ML 孔内距离与 MM 管的存在呈反比关系（P<.05，OR=0.73）。年龄小于 42 岁的患者在 CBCT 扫描中发现 MM 管的可能性是年龄大于 42 岁的患者的 4 倍（P<.05，OR=3.9）。
牙髓室底的建议解剖标志可作为存在 MM 管的可靠预测因子。这些解剖线索的知识可以更好地指导牙髓病医生定位 MM 管，从而防止过多地去除牙体结构。
