下颌阻生智牙拔除术中下牙槽神经血管束损伤风险因素分析

摘要/Abstract

摘要： 目的：以下颌阻生智牙与下牙槽管（inferior alveolar canal,IAC）的接触程度和方位关系为下牙槽神经血管束损伤风险因素,对阻生牙行分级和分类,以预测风险和指导手术。方法筛选同一术者用超声骨刀拔除的105例连续病例116颗困难下颌阻生智牙中全景片示与IAC接触的92颗牙,利用全景片和锥形束CT（CBCT）,根据牙与IAC的接触程度分接触（Ⅰ级）、压迫（Ⅱ级）和突入（Ⅲ级）。用Kappa值和youden指数（以CBCT为金标准）比较2种影像学检查结果。利用CBCT,根据牙与IAC的方位关系将样本分为牙根位于IAC舌侧（Ⅰ类）、正上方（Ⅱ类）、颊侧（Ⅲ类）和包绕IAC（Ⅳ类）。统计不同级别和类别阻生牙拔除的实际下牙槽神经血管束损伤率,用Fisher确切概率法分析更易引起损伤的阻生牙类型。采用SAS 8.2软件包对数据进行统计学分析。结果 79.31%（92/116）的困难阻生牙具有下牙槽神经血管束损伤风险。全景片评价Ⅰ、Ⅱ、Ⅲ级分别占33.70%、28.26%和38.04%,CBCT评价Ⅰ、Ⅱ、Ⅲ级分别占36.96%、33.70%和29.35%,两者一致性很好（Kappa值0.8699）。全景片误判为Ⅲ级者实际可为Ⅰ或Ⅱ级。Ⅰ、Ⅱ、Ⅲ、Ⅳ类分别占31.52%、55.43%、11.96%和1.09%。7.61%（7/92）的阻生牙拔除时出现下牙槽神经血管束损伤（3例Ⅲ级Ⅲ类,2例Ⅲ级Ⅱ类,2例Ⅱ级Ⅱ类）。接触程度级别越高,出现损伤的比例越高（P<0.05）;出现损伤比例以牙根位于IAC颊侧者最高,正上方次之（P<0.05）。结论全景片能较好评价牙与IAC的关系,CBCT能弥补全景片重叠影像的缺陷,并可提供两者的方位关系。该分级和分类能全面预测风险和指导手术。Ⅱ~Ⅲ级和Ⅱ~Ⅲ类阻生牙更易出现下牙槽神经血管束损伤,操作时勿对神经直接施力。

关键词: 困难下颌阻生智牙拔除术, 下牙槽神经血管束损伤, 全景片, 锥形束CT

Abstract: PURPOSE : To suggest a risk degree and classification according to the contact and positional relation between root and inferior alveolar canal (IAC) for prognosis estimation and surgery design. METHODS : Consecutive cases with complicated mandibular third molars underwent extraction using piezosurgery were reviewed. Those teeth contacted IAC in panoramic radiographs were included, and classified into degree Ⅰ (contact), Ⅱ (compress), Ⅲ (penetrate) according to the contact relation between root and IAC in both panoramic radiographs and cone-beam CT (CBCT). Kappa test and youden index were used to compare two imaging RESULTS. The included teeth were categorized into class I (root on the buccal side), Ⅱ (above IAC), Ⅲ (on the lingual side), Ⅳ (surrounding IAC) according to the positional relation. Inferior alveolar nerve and vessels injury rates of teeth in different degrees and categories were recorded. Fisher’s exact probability was used to analyze the difference of injury rates in teeth of different degrees and categories. Statistical analysis was performed using SAS 8.2 software package. RESULTS : 79.31% (92/116) of complicated mandibular third molars had inferior alveolar nerve and vessels injury risk (33.70%, 28.26%, 38.04% in risk degree Ⅰ, Ⅱ, Ⅲ according to the evaluation of panoramic radiographs, 36.96%, 33.70%, 29.35% in risk degree Ⅰ, Ⅱ, Ⅲ according to CBCT). The concordance of two images RESULTS was better on Kappa test (Kappa=0.8699). Teeth in risk degree Ⅰ, Ⅱ were occasionally mistaken for Ⅲ in panoramic radiographs. The percentages of teeth in class Ⅰ, Ⅱ, Ⅲ and Ⅳ were 31.52%, 55.43%, 11.96% and 1.09%. 7.61% (7/92) of teeth developing inferior alveolar nerve and vessels injuries during extractions (3 in degree Ⅲ class Ⅲ, and 2 in degree Ⅲ class Ⅱ, 2 in degree Ⅱ class Ⅱ). Teeth in higher risk degrees had higher percentage to injure inferior alveolar nerve and vessels (P<0.05). The injury rate was highest in teeth whose roots were on the buccal side of IAC (P<0.05). CONCLUSIONS : Panoramic radiographs could evaluate the contact relation between root and IAC. CBCT can overcome the limitation of overlapping structures and provide positional relation. Extractions of teeth in degree Ⅱ or Ⅲ and class Ⅱ or Ⅲ are easier to cause inferior alveolar nerve and vessels injuries. Direct force should be avoided during extraction.

Key words: Complicated mandibular third molar extraction, Inferior alveolar nerve and vessels injury, Panoramic radiography, Cone-beam CT

中图分类号:

R782.1

叶周熹，杨驰. 下颌阻生智牙拔除术中下牙槽神经血管束损伤风险因素分析[J]. 中国口腔颌面外科杂志, 2016, 14(1): 51-56.

YE Zhou-xi, YANG Chi. Risk factors of inferior alveolar nerve and vessels injury in the mandibular third molar extractions: the contact and positional relation between root and inferior alveolar canal[J]. China J Oral Maxillofac Surg, 2016, 14(1): 51-56.

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