下颌骨牵张成骨和牵张器拆除时机的评价

目的:牵张成骨是治疗颌骨畸形和骨缺损的新方法,但力学研究及由此而确立的牵张器拆除时机的研究甚少。通过建立了山羊下颌骨牵张模型,观察下颌骨牵张后的物理、机械特性,探索牵引器拆除的时间。方法:8只山羊单侧下颌骨2次/d,1mm/d,共8d,后以牵开器继续固定至4周,行放射学、组织学、骨密度及力学测试。结果:牵拉术后下颌骨成骨明显,牵拉后2周,X线示骨间隙内新骨已基本连接骨缺损,4周时骨化明显。其骨密度与正常松质骨无明显差别,极限载荷为正常侧的61%。结论:生长期山羊为一良好的下颌骨牵张模型动物,牵拉后4周可以考虑去除牵开器。

Evaluation of mandibular distraction osteogenesis and time of distractor removal in the goats

AIM:To establish an animal model of mandibular distraction osteogenesis in goats and evaluate its physical and biomechanical properties. To explore time of the distractor removal.METHODS:Eight goats were used for experiment. Extraoral distractors were activated 7 days after mandibular corticotomy at a rate of 0.5 mm twice daily, for 8 days. Radiographic examination, bone densitometry and 3 point mechanical testing were performed on the harvested mandibles.RESULTS:Radiographic evaluation suggested definite ossification.Mineralized tissue was seen bridging the defect as early as 2 weeks.Analysis of the new bone densities failed to reveal any statistical differences between the control group and experimental group.The average peak load of the lengthening group was 61%of the control group at 4 weeks after lengthening.CONCLUSIONS:The goat is a good animal for the experiment of distraction osteogenesis. Distractor removal at 4 weeks after lengthening may be accepted.