山羊下颌角截骨术后咬肌的变化

目的 观察山羊下颌角弧形截骨术后咬肌的形态变化,为临床下颌角肥大矫治手术提供实验依据.方法 将10只成年山羊随机平均分为A、B两组.A组行单侧下颌角弧形截骨术;B组行单侧下颌骨咬肌剥离术,各实验组另侧为对照组.分别于术前及术后不同时间点测量各组山羊咬肌肌纤维横截面积及肌小节长度.结果 A组术后1、2、3、6个月咬肌肌纤维横截面积均有不同程度减少,与对照组相比差异有统计学意义(P<0.01);B组术后1个月时咬肌肌纤维横截面积减少,与对照组相比差异有统计学意义(P<0.01),术后2、3、6个月与对照组相比差异无统计学意义(P>0.05);A组术后1周、1个月、2个月咬肌肌小节长度均有不同程度减少,与对照组相比差异有统计学意义(P<0.01),术后3个月时肌小节长度恢复正常;B组术后1周及术后1个月时咬肌肌小节长度减少,与对照组相比差异有统计学意义(P<0.01),术后2个月时肌小节长度恢复正常.结论 下颌角弧形截骨术后咬肌会有一定程度的萎缩,截骨术对咬肌功能并无明显影响,对于轻、中度下颌角咬肌肥大者,无需去除部分咬肌,既可达到术后美容效果,又可减少术后并发症的发生.

Changes of masseter muscle following curved osteotomy of mandibular angle in goats

Objective To investigate the changes of the masseter muscle following osteotomy of the prominent mandibular angle and to provide guidance for the resection of mandibular angle. Methods Ten goats were equally divided into two groups. In group A we performed unilateral curved osteotomy of the mandibular angle, and in group B we performed unilateral dissection of the masseter muscle. The cross section area (CSA) and the sarcomere length of masseter muscle were measured beore and after operation. Results (1) Cross section area (CSA) of masseter muscle fiber in curved ostectomy group decreased at 1,2, 3 and 6 months after operation in different extent. Comparing with the control group, the difference was statistically significant (P<0.01). CSA of masseter muscle fiber in dissection group decreased 1 month postoperatively, which had significantly statistic difference with control group (P<0.01). But, they had no significant difference with control group at 2, 3, and 6 months after operation (P>0.01). (2) Sarcomere length of masseter muscle in curved ostectomy group decreased in 1 week, 1 and 2 months after operation, which had significantly statistic difference with control group (P<0.01). At 3 months after operation, sarcomere length recovered to normal. In dissection group, sarcomere length decreased in 1 week and 1 month after operation, which had significantly statistic difference with control group (P<0.01). At 2 month after operation, it recovered to normal. Conclusion Certain extent of atrophy does happen to masseter muscle after mandibular angle ostectomy. Meanwhile, these changes do not significantly impair the function of masseter muscle. According to this, we suggest a simple mandibular angle ostectomy without partial resection of masseter muscle in case of mild to morderate mandibular angle hypertrophy. Doing so, we can not only achieve the cosmetic effect but also reduce the implications.