Chen Kenan, Chen Youbai, Chen Peng, Jiang Junqi, Wang Enbo, Guo Chuanbin, Xu Xiangliang
Department of Oral and Maxillofacial Surgery, Peking University School and Hospital of Stomatology & National Center of Stomatology & National Clinical Research Center for Oral Diseases & National Engineering Research Center of Oral Biomaterials and Digital Medical Devices & Beijing Key Laboratory of Digital Stomatology & Research Center of Engineering and Technology for Computerized Dentistry, Ministry of Health & NMPA Key Laboratory for Dental Materials, Beijing, P.R. China.
Department of Plastic and Reconstructive Surgery, The First Medical Center of Chinese PLA General Hospital, Beijing, P.R. China.
BMC Oral Health. 2025 Mar 7;25(1):353. doi: 10.1186/s12903-025-05716-w.
This study aims to evaluate the accuracy of cone beam computed tomography (CBCT) in predicting the exposure of inferior alveolar nerve (IAN) during complicated mandibular third molars (M3M) extraction.
115 M3Ms with canal cortical defect signs on preoperative CBCT were extracted. Candidate variables included sex, age, types of CBCT machine, the Winter classification of M3Ms, the size of root entering the canal on CBCT, the size of cortical defect on CBCT. The primary outcome was the exposure of IAN and the exposed neurovascular bundle size which was recorded measured under endoscope. The independent sample t-test, Bland-Altman analysis was performed to assess the agreement between the CBCT and endoscopic measurements. The regression analysis was performed to determine if there was a correlation between the measurements of CBCT and endoscope. The Chi-square test was used to evaluate whether the proportion of IAN exposure in different impacted M3M types were consistent. ANOVA was used to test the correlation between the actual size of exposed IAN and (1) Winter classification types; (2) types of CBCT machine.
85/115 (73.9%) M3Ms with canal cortical defect signs on preoperative CBCT had intraoperative exposure of IAN. The average length and width of the exposed IAN were 5.89 ± 1.72 mm and 2.48 ± 0.79 mm, which were significantly smaller than the size of root entering the canal on CBCT (9.69 ± 3.05 mm and 3.26 ± 0.87 mm, P < 0.001) but larger than the cortical defect size (5.06 ± 2.05 mm and 2.10 ± 0.54 mm, P < 0.05). The regression analysis showed that IAN exposure was significantly associated with the cortical defect length (0.1 mm) on CBCT (OR = 1.38, P = 0.001). The probability of intraoperative IAN exposure was statistically different among different Winter classifications of M3M and the probability of IAN exposure was higher in non-horizontal impacted type according to Chi-square test results. ANOVA showed statistical difference between exposed IAN length and Winter classification types (p = 0.001).
Not all M3Ms with tooth-IAN contact signs on preoperative CBCT indicated intraoperative IAN exposure. The size of root entering the canal on CBCT were mostly larger than the intraoperative endoscopic measurements. IAN exposure can be accurately predicted by the length of cortical defect on CBCT. Non-horizontal impaction predisposed the M3M to a higher risk of intraoperative IAN exposure.
Endoscope provides the possibility to observe and record the IAN exposure directly. IAN exposure can be accurately predicted by the length of cortical defect instead of the size of root entering the canal on CBCT. Non-horizontal impaction predisposed the M3M to a higher risk of intraoperative IAN exposure.
Not applicable.
本研究旨在评估锥形束计算机断层扫描（CBCT）在预测复杂下颌第三磨牙（M3M）拔除术中下牙槽神经（IAN）暴露情况的准确性。
对115颗术前CBCT显示有根管皮质缺损征象的M3M进行拔除。候选变量包括性别、年龄、CBCT机器类型、M3M的Winter分类、CBCT上进入根管的牙根大小、CBCT上皮质缺损的大小。主要结局是IAN的暴露情况以及在内窥镜下记录测量的暴露神经血管束大小。采用独立样本t检验、Bland-Altman分析评估CBCT与内窥镜测量结果之间的一致性。进行回归分析以确定CBCT测量值与内窥镜测量值之间是否存在相关性。采用卡方检验评估不同类型阻生M3M中IAN暴露比例是否一致。采用方差分析检验IAN实际暴露大小与（1）Winter分类类型；（2）CBCT机器类型之间的相关性。
115颗术前CBCT显示有根管皮质缺损征象的M3M中，85颗（73.9%）在术中出现IAN暴露。暴露的IAN平均长度和宽度分别为5.89±1.72mm和2.48±0.79mm，明显小于CBCT上进入根管的牙根大小（9.69±3.05mm和3.26±0.87mm，P<0.001），但大于皮质缺损大小（5.06±2.05mm和2.10±0.54mm，P<0.05）。回归分析显示，IAN暴露与CBCT上的皮质缺损长度（0.1mm）显著相关（OR=1.38，P=0.001）。根据卡方检验结果，不同Winter分类的M3M术中IAN暴露概率在统计学上存在差异，非水平阻生类型的IAN暴露概率更高。方差分析显示暴露的IAN长度与Winter分类类型之间存在统计学差异（p=0.001）。
并非所有术前CBCT显示有牙齿与IAN接触征象的M3M在术中都会出现IAN暴露。CBCT上进入根管的牙根大小大多大于术中内窥镜测量值。CBCT上的皮质缺损长度可准确预测IAN暴露情况。非水平阻生使M3M术中IAN暴露风险更高。
内窥镜为直接观察和记录IAN暴露提供了可能。CBCT上的皮质缺损长度而非进入根管的牙根大小可准确预测IAN暴露情况。非水平阻生使M3M术中IAN暴露风险更高。
不适用。
