兔下颌角骨外板磨除术后咬肌不同处理方式与骨的适应性研究

目的:通过对兔下颌角骨外板磨除术后咬肌不同处理方式与骨的适应性相关指标的测定,比较咬肌不同处理方式与下颌骨变化的差异,为下颌角肥大手术方式的选择提供依据.方法:雌性家兔50只,3个月龄,分为2组,每组25只.左侧为手术侧,第1组行下颌角骨外板磨除术后将咬肌与翼内肌缝合,第2组行下颌角骨外板磨除术后咬肌不做缝合固定.每组在术后第1、2、4、8、12周时分别处死5只动物,手术侧咬肌称重,切取手术侧部分骨组织连同其上部分咬肌作病理切片,行HE染色,光镜下观察细胞形态,在200倍镜下用HJ-YG病理诊断分析系统测量肌小节长度和肌细胞面积,用游标卡尺测量下颌骨的厚度.采用SPSS 13.0软件包对数据进行统计学分析.结果:术后第4、8、12周,第2组咬肌重量减轻,与第1组相比有显著性差异(P＜0.05).术后4、8、12周,第2组下颌骨厚度未增加,第1组下颌骨厚度增加,有显著性差异(P＜.05).术后1、2、4周,第2组肌小节长度较第1组短,有显著性差异(P＜0.05).术后8、12周,第2组肌细胞面积较第1组小,有显著性差异(P＜0.05).结论:兔下颌角骨外板磨除术后肌小节长度、咬肌细胞面积、骨细胞等发生了适应性改建,尤其是游离咬肌后咬肌失去张力,其附着点上移,致使其发生明显萎缩.下颌骨愈合后厚度不增加.

Changes of masseter muscles and bone after outer plate grinding in rabbit mandibular angle using two types of procedure

PURPOSE：To study the changes of masseter muscle and bone after outer plate grinding in rabbits using two types of procedure,to provide reference for mandibular angle surgery.METHODS：50 female rabbits aged 3 months were divided into 2 groups（25 in each group）.The left side was used as the operation side.In the first group,the masseter muscles were sutured with medial pterygoid muscles after mandibular angle outer plate grinding,while in the second group,no suture was conducted.Five rabbits in each group were killed and selected tissues were harvested at the 1th,2th,4th,8th and 12th week,respectively.The masseter muscles were weighed,the mandibular bone with a part of masseter muscles on the operation side were cut for histopathological examination.Cell morphology was observed under microscope.The muscular cell area and Sarcomere length were measured using HJ-YG Pathological Diagnosis and Analysis System,The mandibular thickness was measured with calipers.The data was analyzed with SPSS 13.0 software package.RESULTS：The weight of masseter muscles decreased in the second group at 4th,8th,12th week after surgery,there was significant difference between the two groups（P0.05）.The thickness of mandibular angle had no change in the second group;on the contrary,significant changes were found in the first group at 4th,8th,12th week,respectively.Sarcomere length of the second group was shorter than that of the first group at 1st,2nd,4th week after surgery（P0.05）.The masseter muscle cell area of the second group were smaller than that of the first group at 8th,12th week after surgery（P0.05）.CONCLUSIONS：The masseter muscles lost tension and the attachment moved upward after grinding of the outer plate of the mandibular angle,resulting in obvious atrophy of the masseter muscles.