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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: To study the anatomic structure of mandibular branch of patients with mandibular protrusion by cone beam computed tomography (CBCT), and evaluate the relationship between the movement of mandibular canal and the postoperative neurosensory disturbance (NSD). METHODS: Twenty-eight patients with skeletal class Ⅲ mandibular prognathism underwent bilateral maxillary sagittal osteotomy. The mandibular images were taken by CBCT machine and were measured in 5 planes from the maxillary hole to the first molar. One dimension was measured from the lateral wall of the mandibular canal to the cortical bone of the buccolophobia and the lower edge of the mandible. A subjective evaluation of the relationship between the buccal bone marrow cavity width and postoperative neurosensory disturbance (NSD) was performed. Measurement results using SPSS l7.0 software for statistical analysis. The relationship between mandibular canal and buccal cortical bone is divided into separate type, contact type and fusion type. NSD occurs when the mandibular canal is fused to the buccal cortical bone, and more than one year is found in 50% of patients, believing that NSD has long-term sustainability. When the medullary cavity width was less than 0.8 mm, the possibility of NSD still existed at 15 days after operation, which was 75%. However, when the medullary cavity width was 1.2 mm or wider, the sensory disturbance recovered after 15 days. CONCLUSION: The total length of the mandibular canal is close to the lingual side. NSD is more likely to occur when the width of the medullary cavity is less than 0.8 mm. Preoperative CBCT precise measurement of the movement of the mandibular canal, especially found in patients with fusion, it is recommended to choose other safer surgery to reduce unnecessary damage to the alveolar nerve.