牙冠去除技术拔除邻近下牙槽神经的49例阻生智牙临床分析

Clinical analysis of 49 cases with coronectomy for extraction of impacted wisdom tooth contacting inferior alveolar nerves

目的:通过观察下颌智牙截冠后牙根移动速率与患者年龄、性别、牙根数目、阻生方向、新骨形成特点等因素之间的相关性,综合评价牙冠去除技术的临床适用范围。方法:49例智牙通过锥形束CT(CBCT)确定牙根与邻近下颌神经管的关系,测量截冠后牙根移动距离,并分析牙根移动速率特点。对牙根移动速率与患者年龄、性别等因素的相关性进行推导,尝试拟定牙根移动速率公式;通过牙根移动速率公式,结合临床操作,确定牙冠去除技术的适用范围。结果:垂直阻生及近中阻生的单根下颌智牙,二期手术的适宜时限可推定在200 d内,牙根移动距离可根据拟合方程D=K×(7×10^(-8)x^(2)×10^(-5)x+0.0239)x·sinθ1,进行推算;而近中阻生多根下颌智牙,二期拔除牙根手术时间在90 d以内。预判牙根移动可达到安全距离为牙冠去除技术适用的主要依据,结论:判断牙根移动最大距离是评价牙冠去除技术适用范围最主要的指标,需根据不同情况,使用公式进行预判,以提高成功率。

PURPOSE: The clinical suitable range of coronectomy for extraction of impacted wisdom tooth contacting inferior alveolar nerves was comprehensively analyzed by the correlation between the root movement distances and rates of mandibular wisdom tooth, with age, gender, number of roots, impacted angle and the characteristics of new bone formation.METHODS: In 49 patients with root compression of mandibular canal determined by cone-beam CT(CBCT), the root movement distances were measured and the characteristics of root movement rates was proposed;the relationship between rates of root movement and age, gender, root morphology was analyzed, and the appropriate equation of root movement rate was formulated. The application range of coronectomy was determined by the formula of root movement rate combined with clinical operation. RESULTS: The safe distance and the time of residual root extraction could be predicted for the vertically impacted and proximally impacted single wisdom tooth with the fitting equation D=K ×(7 ×10-8 x2-8 ×10-5 x +0.0239)x·sinθ1 within 200 days;the second stage of residual root extraction should be controlled in 90 days for the mesioangular impaction, impacted wisdom tooth with multiple-root. The reachable safe distance of the predicted root movement can be used as the main basis for the application of coronectomy to wisdom tooth contacting inferior alveolar nerves. CONCLUSIONS: Estimating the maximum distance of root movement is the main indicator to evaluate the application scope of coronectomy, the formula should be used and pre-judged in accordance with different situations in order to improve the success rate of coronectomy.