下颌骨牵引成骨与直接延长术的组织学比较

目的：通过对下颌骨牵引成骨与直接延长术组织学变化的对比研究分析，探讨牵引成骨的成骨机制。方法：24只狗随机分为牵引成骨组和直接延长组各12只，用HE染色光镜组织学检查方法分别观察牵引第6天、牵引后固定2、8周不同时期的两组组织学变化。结果：牵引组在牵引后固定第8周，牵引区几乎完全由新生的骨组织连接修复，成骨方式是以膜内成骨为主，伴有少量的软骨内成骨；而直接延长组仅早期在两骨断端附近可见活跃的膜内成骨，两周以后则以软骨内成骨为丰，中间区域仍为大量的纤维结缔组织，8周以后成骨量增加．但中央仍为软骨组织和纤维组织间隔。结论：牵引成骨以膜内成骨为主，达到良好的骨愈合，直接延长成骨效果不稳定，容易导致成骨不良。

The Observation of Histological Change in Mandibular Distraction Osteogenesis and Acute Lengthening

Objective: To study the osteogenesis mechanism in mandibular distraction osteogenesis by comparison investigation between gradual distraction and acute lengthening. Methods: 24 adult dogs were randomly divided into gradually distracted group (n=12) and acutely lengthened group(n=12).4 animals were respectively sacrificed in the 6th day of distraction, 2,8 weeks after completion of distraction and corresponding time in two groups. The change of histology were observed by HE micrograph examination. Results: In gradually distracted group, the distraction gaps were nearly completely ossified after 8 weeks of consolidation, the major mode of new bone formation appears to be intramembranous ossification, few endochondral ossification takes place; In acutely lengthened group, active endochondral ossification existed along the osteotomized bone edges in early stage too, but the major mode of new bone formation appeared change to be endochondral ossification after 2 weeks ,fibril connective tissue and endochondral tissue were filled in the medial area 8 weeks. Conclusions: The major mode of new born formation in distraction osteogenesis is intramenbranous ossification, and result in bone union;the formation of new bone in acutely lengthening is not efficient, lead to unhealthy union.