下颌管定位与下颌支矢状骨劈开术后感觉神经障碍相关性的临床观察

Position of mandibular canal as factor in development of neurosensory disturbance after sagittal split ramus osteotomy

目的用CT扫描来确定下颌前突患者下颌支部下颌管的定位,并评价下颌管与颊侧骨皮质之间骨髓腔宽度与术后感觉神经障碍(NSD)之间的关系。方法把通过下颌管最先形成的平面作为基础平面1,紧邻下颌第二磨牙远中与平面1相垂直作为平面5,二者角分线为平面3,平面1和3,3和5的角分线分别为平面2和4,共5个平面,在每一平面测量颊侧骨髓腔的宽度。以问卷的形式描述术后下牙槽神经分布区域的感觉改变。测量结果采用SPSS13.0软件包进行统计学分析。用卡方检验评价骨髓腔宽度和术后NSD之间的关系。结果颊侧骨髓腔宽度左右两侧无显著性差异(t=-0.871,P=0.384),其宽度的总体变化没有规律,在3、4层面距离最小,各层之间差异有显著性(F=2.795,P=0.017)。颊侧骨髓腔缺如(接触和融合型),在3和4层面出现几率较高。颊侧骨髓腔宽度为0的27侧100%发生术后NSD。未接触组63侧有14.3%发生术后NSD,两组间差异有显著性(χ2=25.941,P<0.05)。结论颊侧骨髓腔的宽度是术后NSD的风险因子,当下颌管和颊侧骨皮质之间的骨髓腔宽度是0.9mm或更小时,NSD更容易发生,当颊侧骨髓腔缺失时,从外侧骨皮质中分离下牙槽神经十分困难。

Obsjective To investigate the position of the mandibular canal in patients with mandibular prognathism using computed tomo- graphic scanning,and evaluate the relationship between the width of the bone marrow space at the buccal and the NSD after SSRO. Methods The mandibles of 45 patients with skeletal Class Ⅲ prognathism undergoing sagittal split ramus ostootomy were observed on spiral computed tomography. The base plane where the mandibular formau originally took shape was the plane 1. The plane 5 which was close to the distal of the mandibular second molar was vertical to the plane 1. The plane 2,3,4 were the corner-point line of the plane 1 and 3,plane 1 and 5 ,plane 3 and 5 ,respectively. The width of the marrow space at buccal was measured at every plane. The neurosensory disturbance was described after SSRO in the way of questionnaire. All measurements were analyzed with SPSS 13.0,and a p value less than 0.05 was considered a statistically significant difference. Results There were no statistically significant differences between left or right sides （t = -0. 871,P = 0. 384）. There was no variation law of the width ,and a significant statistic difference was found among the planes（ F = 2. 795 ,P =0. 017）. The NSD was bound to happen in the group whose buccal bone marrow was absent ,and there were only 14.3% patients who had the buccal bone marrow come about the NSD. This difference was statistically significant （χ2 = 25.941,P 〈 0. 05 ）. Conclusions The width of the bone marrow space at the buccal was a risk factor for NSD after SSRO. When the width was 0.9 mm or less,NSD was prone to happen. It was difficult to sepa- rate the inferior alveolar nerve from the buccal cortical when the width was absent.