下颌骨牵引成骨过程及机理的实验研究

The preliminary experimental study of mandibular distraction osteogenesis process and mechanism

目的 观察猴下颌骨牵引成骨的动态过程 ,探讨其成骨方式及机理。方法 恒河猴 10只行单侧下颌骨牵引 ,间歇期 5天 ,牵引速度 0 .5mm× 2次 /日 ,共 15天。于牵引后不同时期拍摄X线片 ,行四环素荧光双标记 ,将牵引区骨块标本平分 ,上部骨块制作不脱钙树脂切片 ,5u切片行甲苯胺蓝染色 ,2 0u切片荧光显微镜下测骨组织沉积率 ;下部骨块制作脱钙石蜡切片 ,HE染色。结果 牵引后早期 ,牵引区以平行于牵引方向排列的胶原纤维为主 ,可见纤细骨小梁及大量骨吸收陷窝 ,X线片上表现为低密度透光区。稳定期新骨逐渐由两端向中间形成 ,牵引后 4周 ,牵引中心充满平行排列的骨小梁 ,新骨密度仍低于正常 ;牵引后 6～ 12周 ,牵引区粗大的骨小梁呈网状排列 ,可见成熟哈佛氏系统 ,新骨表面形成骨皮质 ,X线片表现接近正常。牵引完成时骨组织沉积率为对照组的4.2倍 ,在稳定期逐渐减慢 ,但牵引后 12周时仍较对照高 40 .91%。结论 缓慢有规律地牵引下颌骨可明显促进新骨形成速度 ,延长骨段。牵引后足够时间的稳定期是新骨生成的必要条件。牵引区主要以膜内成骨方式形成新骨 ,成骨过程为新生与改建并存。

Objective To observe and probe into the process and mechanism of mandibular distraction osteogenesis(DO).Methods 10 rhesus monkeys were used to do unilateral mandibular DO. After 5 days latency period, the distractor was initiated at a rate of 0.5mm ×2/day , totally 15 days. At different periods, X-ray films were taken and tetracycline was given. The bone in the distraction gap was divided into two pieces. The upper half was embedded in acrylic resin, 5u thick slices were stained by toluidine blue and 20u thick slices were observed under fluorescence microscope to calculate the appositional rate. The lower half was decalcified, embedded in paraffin and stained with Hematoxylin & Eosin.Results At the early period after distraction, the distraction gap was mainly occupied by collagen fibers, appeared as transparent region on X-ray film. Slim bone trabeculae and lots of osteoclasts were seen. During consolidation period, new bone gradually formed from osteotomy line to distraction center. 4 weeks after distraction, the distraction gap was all occupied by parallel trabeculae, but its density is still lower than normal. 6～12weeks after distraction, the trabeculae was thick and connected like wove. Mature Havers' system and lamellae bone can be seen. The X-ray appearance was nearly normal. When distraction completed, the apposition rate was 4.2 times higher than control, and gradually slowed during consolidation period, but was still 40.91% higher than normal after 12 weeks.Conclusion Slowly and systemic mandibular distraction can highly accelerate new bone formation rate. 12 weeks consolidation period is least to ensure good new bone formation in distraction gap. Bone remodeling and bone formation are alternatively progressed during process of DO.