中文摘要：

目的探讨扩张力对大鼠腭中缝重建新骨形成过程中细胞凋亡的影响及意义。方法55只大鼠随机分为实验组（A组，25只）和对照组（B组，30只）。A组再均分为5个亚组：A1组，扩弓1d；A2组，扩弓2d；A3组，扩弓3d；A4组，扩弓4d并固定3d；A5组，扩弓4d并固定7d。B组再均分为6个亚组：B0组为扩弓前对照；B1组、B2组、B3组、B4组和B5组分别与实验组对应，但均不扩弓。每组5只大鼠。采用自制两眼簧后牙扩弓器扩张A组大鼠上颌腭中缝组织，用TUNEL荧光标记法检测凋亡细胞。结果A1组细胞凋亡现象多于B1组（P〈0．01）；A2组凋亡细胞较A1组有所减少，但仍多于B2组（P〈O．05）；A3组凋亡细胞数比A2组有所增加，且多于B3组（P〈0．01）；A4组和B4组以及A5组与B5组凋亡细胞的量和分布差异无统计学意义（P〉0．05）。结论扩张力诱导下细胞凋亡水平的改变在腭中缝组织改建新骨形成过程中有着重要的生物学意义。

英文摘要：

Objective To investigate the effect and significance of maxillary expansion on cell apoptosis during midpalatal bone remodeling in rats. Methods Fifty-five rats were randomly divided into experimental group（group A, 25 rats） and control group（group B, 30 rats）. The midpalatal suture in group A was expanded with the rectangular appliances for 1 day（group A1）, 2 days（group A2）, 3 days（group A3）, 4 days（group A4） and 5 days（group A5） with 5 rats each. The rats in group B without maxillary expansion were equally subdivided into 6 groups of t30 （0 day）, B1 （1 day）, B2 （2 days）,B3（3 days）, B4（4 days） and B5（5 days）. The cell apoptosis was detected by fluorimetric TUNEL test. Results The cell apoptosis was more in group A1 than that in group BI（P〈0. 01）. Compared to group A1, the cell apoptosis was reduced slightly in group A2, which was more than that in group B2 （P〈0. 05）. Compared to group A2, the cell apoptosis was increased slightly in group Aa, which was more than that in group B3（P〈0. 01）. There were no significant differences in the cell apoptosis between groups of A4 and B4 or groups of A5 and B5（P〈0. 05）. Conclusion Cell apoptosis can be induced by expansion force, which may play a role in the signal pathway of bone remodeling during maxillary expansion.