下颌骨牵引成骨过程中血运重建方式初步探讨

目的通过建立兔下颌骨牵引成骨实验动物模型,观察其动态过程,初步探讨血运重建方式及机制。方法选用新西兰白兔30只,6只动物做空白对照组;24只动物行右侧下颌骨植入外置式颌骨牵引器。经7d延迟期后,按1mm/d速率延长下颌骨7d,然后固定8周。在延迟期第7天,牵引期第2、4、7天,固定期第1、3、6、8周时分别处死3只动物,用X线片、苏木精-伊红染色、免疫组化方法检测血管和新骨生成情况,以及微血管密度变化规律。结果实验组22只兔成功进行下颌骨牵引延长,牵引区血管生成方式以芽生和血管上皮岛为主。在牵引期第2天,骨断端微血管密度为28.2±7.0,明显高于其他各组(P<0.01),在固定期下降明显,固定第8周时,微血管密度为4.3±1.3,与正常组无显著性差异(P>0.05)。结论在牵引初期牵引骨断端有强烈的微血管反应,血运重建先于新骨重建;固定期微血管密度降低,血管成熟,血运重建随新骨生成改建完成而结束。

Mode of angiogenesis during mandibular distraction osteogenesis

Objective To study the mode of angiogenesis by establishing a novel experimental model in rabbit for lengthening mandible by distraction osteogenesis. Methods Six rabbits were chosen as control group. Twenty-four rabbits underwent unilateral mandibular distraction(protocol:a 7-day latency period,a 7-day distraction at 0.5 mm per 12 hours for 7days,and an 8-week consolidation period). Samples were collected at the 7th day of latency and at the 2nd,4th and 7th day of distraction and at the 1st,3rd,6th and 8th week of consolidation. The mode of angiogenesis and osteogenesis as well as microvascular density (MVD) were detected immediately by radiographs Hematoxylin Eosin Stain (HE) and immunohistochemistry. Results The twenty-two mandibles were lengthened successfully. There were two modes of angiogenesis during MDO,and new micro-vessel sprouted from the bone edges of surface and periosteal into the centrally located area of distracted mandible primarily. MVD was the highest at 2-day of distraction period with 28.2±7.0 and decreased significantly during the later consolidation period with 4.3±1.3. Conclusion MDO is associacted with an intense vascular response during the early stage of D2,which indicates angiogenesis takes place before osteogenesis. MVD in distraced region decreases significantly during the later distraction and consolidation time points,and angiogenesis completes following osteogenesis termination.