下颌前突患者下颌支的CBCT测量及其与下颌矢状骨劈开术后感觉神经障碍关系的临床研究

Location of the mandibular rami observed with CBCT and its relevance to neurosensory disturbance after sagittal split ramus osteotomy in mandibular prognathism:a clinical study

目的:用锥状束CT(CBCT)研究下颌前突患者下颌支的解剖结构,同时评价下颌管走行与术后感觉神经障碍(neurosensory disturbance,NSD)之间的关系。方法:双侧下颌支矢状骨劈开术的骨性Ⅲ类下颌前突患者28例,使用CBCT机拍摄下颌骨影像,从下颌孔至第一磨牙区域共分为5个平面测量,在每一个层面分别测量下颌管外侧壁至颊舌侧骨皮质及下颌骨下缘的距离。采用主观评价下颌管颊侧骨髓腔宽度和术后感觉神经障碍(neurosensory disturbance,NSD)之间的关系。测量结果采用SPSS l7.0软件进行统计学分析。结果:1.下颌管与颊侧骨皮质的关系分为分开型、接触型和融合型。2.当下颌管与颊侧骨皮质为融合型时均发生NSD,而且有50%患者超过1年,认为NSD有长期持续性。在骨髓腔宽度小于0.8 mm时,术后15 d仍存在NSD可能性为75%,而在骨髓腔宽度为1.2 mm或更宽时,术后15 d感觉障碍可恢复。结论:下颌管的总体走行靠近舌侧,当其颊侧骨髓腔宽度≤0.8 mm,NSD更容易发生。术前通过CBCT精确测量下颌管的走行,尤其是发现融合型的患者,建议选用其它更安全的术式,减少下牙槽神经不必要的损伤。

Objective：This study aimed at investigating the anatomic location of mandibular prognathism with Conebeamcomputerized tomography（CBCT）,as well as evaluating the relationship between the course of the mandibular canalwith neurosensory disturbance（NSD） after the operation to assist in designing and performing sagittal split ramus osteotomy（SSRO）. Patients and Method：The subjects included 28 skeletal Class III patients who underwent bilateral SSRO. Measurementswere made on five planes for each mandibles from mandibular foramen to mandibular body at the portion of thefirst molar with CBCT. Each plane was detected including width between the mandibular canal and medial and lateral corticalbone and distance from mandibular canal to inferior border of mandible. The subjective evaluation was performed to relatethe width of bone marrow space at the buccal side and neurosensory disturbance（NSD）. Analyses were performed bySPSS 17.0 statistics software. Result：①.The width of bone marrow space at the buccal side could be classified into separatetype,contact type and fusion type. ②.NSD occurred in all cases of fusion type,50 % of which were considered long lastingNSD for presenting over one year. 75 % of cases continued NSD over 15 days in which the width of bone marrow space wasless than 0.8mm, while NSD regained in 15days where the bone marrow space was wider than 1.2 mm. Conclusion：Themandibular canal is situated lingually on average. A higher incidence of NSD occurred where the width of buccal side bonemarrow space was less than 0.8mm. Other safer orthognathic surgical procedure was recommended depending on the measurementsof mandibular canal with CBCT before SSRO to reduce the injury to the inferior alveolar nerve,especially in fusiontype cases.