中文摘要：

目的：研究功能矫形前伸大鼠下颌后浅层嚼肌细胞凋亡的变化规律,探讨功能矫形的肌肉改建机理。方法：选用50只5周龄Sprague-Dawley（SD）雄性大白鼠,随机分为实验组和对照组各25只。实验组大鼠戴自制上颌功能矫治嚣,引导下颌前伸,并打开咬合。利用RT-PCR方法检测两组大鼠浅层嚼肌Bcl-2和Bax基因表达情况,利用TUNEL方法检测浅层嚼肌细胞凋亡情况。结果：①Bcl-2和Bax基因表达随大鼠戴用矫治器时间的延长而升高,至第3周开始下降但仍高于对照组,但Bax的表达高于Bcl-2。Bax/Bcl-2比值随大鼠戴用矫治器时间的延长而升高,至第4周开始下降。②TUNEL实验结果显示浅层嚼肌细胞在戴用矫治器1天后,开始出现凋亡,随着时间延长而增加,至第3周达到顶峰,第4周开始下降。结论：①Bax/Bcl-2比值升高促进浅层嚼肌细胞凋亡。②功能矫形可引起浅层嚼肌细胞凋亡,导致肌肉的结构和功能发生适应性改建。

英文摘要：

Objective：To investigate the relationship of the apoptotic superficial masseter muscle cells after functional mandibular advancement on juvenile rats.Methods：Fifty 5-week-old male Sprague-Dawley（SD） rats were randomly divided into experimental and control groups.The mimic functional appliances were used in experimental groups,and the rats of two groups were killed on 1st,7th,14th,21th,28th day.The erminal deoxynucleotidyl transferase-mediated deoxyuridine 5-triphosphate nick and labeling（TUNEL） and Hoechst 33258method was used to detect superficial masseter muscle cells apoptosis.Bax and Bcl-2 expression was detected by PCR.Results：① Bax and Bcl-2 expression and the value of Bax/Bcl-2 increased after insertion of the appliance,and reach the peak on the 21st day then decreased.② The apoptotic cells increased after insertion of the appliance,and reach the peak on the 21st day then decreased.Conclusion：① The increased value of Bax/Bcl-2 promoted superficial masseter muscle cells apoptosis.② Superficial masseter muscles cells appeared apoptosis and rebuilt after functional mandibular advancement.