兔下颌角截骨后咬肌适应性变化

目的通过对兔下颌角弧形截骨后咬肌相关指标测定，研究咬肌在骨架缩短后的变化规律。方法3个月龄雌性新西兰大白兔25只，行左侧下颌角弧形截骨，右侧不手术作为自身对照。2、4、8、12和24周分别处死5只动物，双侧咬肌总量称重。取双侧下颌角中点浅部咬肌，行HE、ATP酶染色。结果左侧咬肌重量减轻与右侧差异显著，肌小节长度2周和4周术侧缩短，8周后恢复正常；部分肌纤维Ⅰ型向Ⅱ型转化；Ⅰ、Ⅱ型肌纤维面积左侧较右侧减小。结论兔下颌角截骨术后肌小节长度、肌纤维转型、咬肌细胞面积发生相应变化，表明下颌骨架缩短后咬肌发生适应性的改建。

Adaptive change of masseter muscle after the ostectomy of mandibular angle in rabbits

Objective To study the changes of massester muscle after reducing the mandibular by measuring some relative index after ostectomy of the mandibular angle along arch line. Methods Left mandibular angle ostectomy was performed on New Zealand female rabbits aged three months.The right was not operated as control groups. Five rabbits were examined at the following intervals:2,4,8,12 and 24 weeks. Results There were remarkable decreases in the experimented masseter muscle masses and the same type muscle fiber areas compared with the control group(P<0.05).As for the fiber types,a decrease in type I fibers and an increase in type II fibers were noticed on operative side masseters(P<0.05). Sarcomere lengths in the operative side muscles were significantly reduced and showed statistical significance during first 4 weeks(P<0.05),but there was no difference between the operative group and the control group after 8 weeks (P>0.05). Conclusions The changes of masseter fibres show reconstruction of masseter muscle after mandibular angle ostectomy.