镍钛记忆合金牵张犬腭骨-上颌骨缝超微结构的研究

目的 利用透射电镜观察不同时间段犬腭骨-上颌骨缝内细胞超微结构的变化,以探索颅面部骨缝组织在张力作用下的变化.方法 制作镍钛形状记忆合金(NiTi-SMA)扩张器,并用口腔矫形测力器测定其最大力值为3.5 N.选择8周龄杂种犬45只,随机分为空白对照组、实验对照组、实验组.实验对照组和实验组在全麻下,去除硬腭中部后部骨质,缝合口腔和鼻腔侧黏膜,形成宽约8 mm的腭裂模型.实验组将NiTi-SMA安置在硬腭上,分别于牵张后3、7、14、28、56 d处死动物,并制作电镜标本.透射电镜下观察腭骨-上颌骨缝内细胞的变化过程.结果 电镜下腭骨-上颌骨缝牵张,首先表现为组织断裂,渗出,细胞死亡,随后是骨和纤维生成细胞群增殖活跃,成骨细胞和成纤维细胞功能增强,最终恢复正常缝组织结构.结论 电镜下可以区分缝细胞的类型和功能状态,提示缝牵张是组织修复与再生并存的过程,张力引发细胞反应特别是成骨反应是导致骨缝增宽的主要因素.

An ultrastructure study on the palatomaxillary suture of dog expanded by NiTi-SMA

Objective To explore the ultrasturcture of the palate-maxillary sutures under tensile forces by transmission electron microscope (TEM). Methods The Suture expanders were made in NiTi-Shape memory alloy (NiTi-SMA) .The maximum force was 3.5 N. Fourteen 8-month old mongrel dogs were used in the study. and control groups, an 8 mm wide cleft was made by surgery. The suture expanders were luted onto the palatine bones of the experimental group. The dogs of the experimental group were executed after 3,7,14,28,56 days of suture expansion. The change of suture tissue was examined by TEM. Results The cleft of the experiment group were closed at the ninth day of expansion. At the beginning, tissue rupture, exudation, death of fibroblasts, disruption of collagen and tear vessels were seen at the early stage of suture expansion. Then highly active functional manifestations were seen in both osteocytic and fibrocytic populations. At last, normal structure restored. Conclusions Cell types and functional condition could be distinguished clearly by TEM. It suggests that the suture expansion should be the process of tissue repair and regeneration. The suture cells response, especially, the osteogenic response were the major factor of increasing suture width.