内置式三焦点牵引器重建下颌颏部的动物实验

目的介绍自行研制的内置式三焦点牵引成骨器，探讨其应用效果。方法选取4只杂种犬，手术均截去下颌颏部骨组织，制造出25～30mm的下颌骨正中联合部位骨缺损动物模型。在两侧骨断端分别制作一个宽度约10mm的骨输送盘。安装自行研制的内置式牵引成骨器。术后1周开始加力，牵引速率0．5mm／12h，在13～16d两侧输送盘在正中对接后，牵引结束。术后分期拍下颌横断袷片，在牵引完成后固定第12周时处死动物，取材并观察新骨形成情况。结果所有受试动物均耐受实验全过程，牵引器未见断裂、锈蚀。下颌骨缺损被恢复，牵引区内新生骨组织成熟且骨量充足，两输送盘之间可见增厚、粗糙的外骨痂，已达到骨性愈合。结论自行研制的内置式三焦点牵引成骨器为临床修复下颌骨颏部骨缺损提供了新器械。

Experimental study on the reconstruction of mandibular symphyseal defects by internal trifocal distractor

Objective To introduce the internal trifocal distractor developed by the authors and evaluate its primary application and feasibility in animal experiment. Methods Four hybrid dogs were selected and segmental resection at the mandibular symphysis was performed. Two transfer disks, 10mm in width, were respectively fixed at the two ends of bone defect and the internal trifocal distractor was installed. The force was applied one week after the operation, with a tractive speed of 0. 5 mm/12 h. After 13-16 days, the traction was completed when the two transfer disks were combined. The occlusal films were taken at the lstday, 4th, 8th and 12th week after traction. The animals were killed at the 12th week, samples of the traction area taken and histological examination performed. Finally, the new bone formation was observed. Results All the animals survived in the experiment, abruption and rust-eaten was not found in distractor. In the 12th week after installation, new bones in traction gap were mature and bony union between the two transfer dishes was accomplished. Conclusions The internal trifocal distractor used in this study may become a potential device in reconstruction of mandibular symphyseal defects.