兔下颌骨放疗后牵张成骨的组织学观察

目的观察兔下颌骨放疗后牵张成骨的组织学特征.方法将24只成年新西兰大白兔随机分为放疗组和未放疗组,每组12只.放疗组用60Co机照射大白兔下颌骨,5.4G y/次,隔日1次,共5次,总剂量为27 Gy.3个月后在两组动物下颌骨的双侧截骨处安装牵张器,经5 d延迟期后开始牵张,速率为1 mm/d,0.5 mm/次,2次/d,连续7 d,共延长下颌骨7㎜.分别在固定期的第4、6周处死动物12只, 取下颌骨双侧新生骨痂行组织学检查,观察其成骨特征. 结果组织学观察显示,牵张区以膜内成骨为主,放疗组有更多的软骨形成,但无统计学意义(P》0.05),放疗组较未放疗组新骨骨小梁细小,稀疏.结论放射损伤区牵张成骨是可行的,但成骨质量较差,成骨方式以膜内成骨为主,放射线促进了软骨成骨.

HISTOLOGICAL FEATURES OF DISTRACTION OSTEOGENESIS IN RABBITS' MANDIBLES

ObjectiveTo observe the histological features of distraction osteogenesis in irradiated rabbits' mandibles.MethodsTwenty-four New Zealand white rabbits were randomly divided into two groups,12 in every group.The research group was irradiated by()~(60)Co,(5.4) Gy every time,one time every two days,five times totally.The control group was non-irradiated.Three months later anterior mandibulectomy was performed bilaterally and distractors were fixed.The distractors were activated(0.5) mm every 12 hours to extend the anterior segment 7 mm in 7 days after latency phase of 5 days.The distracted calluses at consolidation phase of 4th and 6th weeks were processed for histopathology analysis.ResultsAt consolidation phase,the new bones in both groups were basically formed in the way of intramembranous ossification.In addition,more cartilages and less new matured bones in irradiated group were formed than that of non-irradiated group at consolidation phase of 4th.New bone trabeculae in irradiated group was not as bulky as those in non-irradiated group at consolidation phase of 6 weeks,but there were no significant statisticaly differences(P>(0.05)).ConclusionDistraction osteogenesis in irradiated tissues is a feasible surgical procedure.However,the quality of new bone in irradiated tissues is worse than that in non-irradiated tissues.The main formation way of new bone is intramembranous ossification,but radiotherapy promotes endochondral ossification.