自体块状皮质骨修复种植区颌骨缺损

背景:自体骨有骨传导、骨诱导及骨生成的特性,同时具有良好的生物相容性,移植后无排斥反应。但关于自体骨块移植后的骨块是完全被吸收替代?还是能保留细胞活性长期存留?仍存在争议。目的:观察皮质骨移植后改建再生过程中的组织学变化。方法:6只健康比格犬麻醉后拔除两侧上颌前磨牙,并去除颊侧宽约10 mm、长约15 mm、厚度约2 mm的骨板,建立上颌骨缺损模型,在双侧下颌骨体颊侧切取相应大小的块状皮质骨并修整边缘。在上颌骨缺损区移植皮质骨块,一侧为单纯块状皮质骨移植,另一侧在块状皮质骨移植同期植入种植体。分别于骨移植后3,6个月取材,进行大体观测和组织学观察,分析移植骨块的吸收率、移植骨中的细胞存活率。实验方案经大连医科大学动物实验伦理委员会批准。结果与结论:①大体观察可见移植骨块体积逐渐缩小,边缘圆钝,与基骨结合稳固;②6个月时全部种植体脱落;硬组织磨片可见移植骨块与基骨间存在新生骨连接;6个月时移植骨骨陷窝孔隙率明显低于3个月,移植骨吸收率显著高于3个月(均P<0.05);③结果说明,块状皮质骨移植后,能够与受植区基骨发生骨结合,其内部的骨细胞部分保持活力,随着愈合期延长,新生骨细胞的比例增加,移植骨块的体积逐渐变小。皮质骨移植同期种植后移植物吸收明显,种植体骨结合不良。

Autologous cortical bone block for repair of implant-site jaw bone defects

BACKGROUND:Autologous bone with good biocompatibility possesses the characteristics of bone conduction,osteoinduction and osteogenesis.However,the healing process after autologous bone grafting is still controversial.The focus of controversy is whether the bone graft is completely absorbed and replaced or whether it can retain cell viability for a long time.OBJECTIVE:To observe the histological changes in bone remodeling and regeneration after cortical bone grafting.METHODS:Six healthy beagle dogs were selected as the research animals.The maxillary premolars of experimental dogs were extracted and the bone plates with width of 10 mm,length of 15 mm and thickness of 2 mm were removed from the buccal side.A bone defect model was established.The corresponding size of cortical bone block was cut on the buccal side of the bilateral mandibular body.Cortical bone grafts were fixed in the maxillary defect area.On one side pure cortical bone block was used as grafting material;on the other side the implant was placed simultaneously with the bone graft.Samples were harvested at 3 and 6 months after bone grafting.The cell survival and bone graft resorption of autologous cortical bone graft were analyzed by gross observation and histological observation.The study protocol was approved by the Animal Ethics Committee of Dalian Medical University,China.RESULTS AND CONCLUSION:The size of the grafted bone was gradually reduced,and the margin was blunt and firmly bonded to the base bone.All implants lost after 6 months.A newly formed connection between the graft and the base bone was shown by hard tissue ground sections.The porosity of bone lacuna in the grafted bone block at 6 months was significantly lower than that at 3 months(P<0.05).The grafted bone resorption rate at 6 months was significantly higher than that at 3 months(P<0.05).These findings indicate that osseointegration exists between grafted cortical bone block and the base bone of the recipient area.Osteocytes in the graft bone partially remain alive.With the prolongation of healing period,the proportion of new bone cells increases,and the volume of the grafted bone gradually decreases.Osseointegration of the concurrent implant is disturbed due to the absorption of cortical bone graft.