下颌前突患者下颌支厚度的CT测量

Measurement of the mandibular ramus in prognathism with computed tomography

目的:应用CT描述下颌前突患者下颌小舌平面下颌支的形态,并与正常对照组进行比较。方法:35例实施下颌支矢状劈开术的骨性Ⅲ类下颌前突患者,20例对照组患者接受螺旋CT扫描,在下颌小舌平面上测量下颌支的厚度、下颌管内径、下颌管外壁到颊侧骨皮质之间骨髓腔的宽度、颊舌侧骨皮质的厚度。采用SPSS13.0软件包对测量结果进行统计学分析,以独立样本t检验比较2组间各项测量值之间的差异。结果:下颌支的厚度分别为实验组8.42mm,对照组9.65mm,下颌管外壁到颊侧骨皮质之间的宽度实验组为1.58mm,对照组为2.39mm。2组下颌支厚度之间存在统计学差异(t=-4.612,Ρ<0.001),实验组显著小于对照组,颊侧下颌管外壁到颊侧骨皮质之间骨髓腔的宽度在2组之间也存在统计学差异(t=-5.434,Ρ<0.001)。结论:与对照组相比,下颌前突患者下颌支的厚度更薄,下颌管外壁到颊侧骨皮质之间骨髓腔的宽度更小。

PURPOSE： The aim of this study is to investigate the morphology of the mandibular ramus at lingual plane using spiral computed tomography and compared with the control patients. METHODS： The mandibles from 35 patients with skeletal Class III prognathism undergoing sagittal split ramus osteotomy and 20 control patients without dentofacial deformity were evaluated on spiral computed tomography. The thickness of the mandible, diameter of the inner mandibular canal, width of the bone marrow space between the outer wall of the mandibular canal and the buccal cortex, and the width of the buccal cortex and lingual cortex was measured at lingual plane. All measurements were analyzed with SPSS 13.0 software package. Differences between groups were tested for statistical significance using Student＇s t test. RESULTS： The thickness of the mandible was 8.42mm in prognathic patients,and 9.65mm in control patients.The width of the bone marrow space at the buccal side in prognathic patients was 1.58mm, and 2.39mm in control patients. There was a significant difference between the two groups in the total thickness of the mandible （t=-4.612,P〈0.001）.This trend was also found in the bone marrow space between the outer mandibular canal and the inner surface of the buccal cortical bone （t=-5.434,P〈0.001）. CONCLUSIONS： Compared with the control patients ,the mandibular ramus of the skeletal Class III is thinner, and the width of the bone marrow space between the outer wall of the mandibular canal and the buccal cortex is smaller.