Abstract: Objective: To investigate the accuracy of three-dimensional imaging parameters in assessing the risk of lower alveolar nerve injuries at third molar surgery. Methods:  3-dimensional imaging parameters of 105 wisdom teeth were enrolled in this review. Pell-Gregory classification and measurement of wisdom teeth (rank and position), horizontal angle and distance (root-inferior alveolar nerve) were performed. The relationship between grade(Ⅰ,Ⅱ,Ⅲ), location(A means impaction of high site, B means median impaction, C means impaction of low site)， horizontal angle and distance between the parameters were analyzed. The assessment of risks of inferior alveolar nerve injuries were also performed. Results: ① The correlation between grade I and A was greater. The correlation between grade Ⅲ and C was greater. ② The grade of Ⅰ, Ⅱ, Ⅰ+Ⅱ is higher than grade Ⅲ. There was a statistically difference in distance(root inferior alveolar nerve) (P<0.05). ③ Horizontal angle (>5° and ≤5°) of the teeth, there was a significant difference in the distance (P<0.05). ④ Ⅰ+Ⅱ grade teeth horizontal angle ≤5° compared to the horizontal angle ＞5°, there was a significant difference in the distance (P<0.05). ⑤ There was significant statistical difference in the distance between the third grade wisdom teeth of horizontal angle >5° and the level of angle >5° (P<0.05). Conclusions: Two kinds of 3-dimensional image parameters (grade parameter and horizontal angle parameter) can be used to evaluate the risk of lower alveolar nerve injury alone, but the clinical accuracy of risk assessment can be improved by using these two parameters simultaneously.

Key words: third molar, Pell-Gregory classification, horizontal angle, cone beam CT, inferior alveolar nerve

摘要：  目的：研究CBCT相关影像学参数用于评估第三磨牙拔除术后下牙槽神经损伤风险的准确性。方法：选取在我科拔除的105颗第三磨牙的影像学资料，测量第三磨牙的Pell-Gregory分类（等级和位置）、水平夹角和距离（牙根-下牙槽神经），分析等级（Ⅰ、Ⅱ、Ⅲ级）、位置（A为高位，B为中位，C为低位）及水平夹角等参数与距离间的关系，从而评价CBCT相关影像学参数用于评估第三磨牙拔除术后下牙槽神经损伤风险的准确性。结果：①Ⅰ等级-A位、Ⅲ等级-C位的相关性较大；②Ⅰ、Ⅱ、Ⅰ+Ⅱ等级相较于Ⅲ等级，其距离（牙根-下牙槽神经）差异有统计学意义（P<0.05）；③水平夹角＞5°和≤5°的第三磨牙，其距离差异有统计学意义（P<0.05）；④水平夹角≤5°的Ⅰ+Ⅱ等级第三磨牙相较于水平夹角＞5°的Ⅰ+Ⅱ等级第三磨牙，其距离差异有统计学意义（P<0.05）；⑤水平夹角＞5°的Ⅲ等级第三磨牙相较于水平夹角＞5°的Ⅰ+Ⅱ等级第三磨牙，其距离差异有统计学意义（P<0.05）。结论：两种CBCT相关影像学参数（等级参数和水平夹角参数）均可单独用于下牙槽神经损伤风险的评估，同时运用这两种参数，可以提高风险评估的准确性。

关键词:  , 第三磨牙；  ,  , Pell-Gregory分类；  ,  , 水平夹角；  ,  , 锥形束CT；  ,  , 下牙槽神经

CLC Number: 

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• R782.4