下颌骨牵张成骨中牵张器拆除时机的实验研究

目的:探讨下颌骨牵张成骨中牵张器的最佳拆除时机。方法:12只山羊随机分为3组,每组各4只,在对动物右下颌骨行骨皮质切开术后进行牵张,第1组动物在牵张后固定期第6周处死,第2组动物在固定期第8周处死,第3组动物在固定期第10周处死,随机选取实验组4只动物的未手术侧下颌骨作为对照组,将各组新骨组织和对照组下颌骨组织分别进行压缩实验和三点弯曲实验,观察新骨生物力学强度随固定期时间延长的变化规律。结果:随着固定期时间的延长,新生骨抗压缩和抗弯曲实验各项力学指标值逐渐增大;固定期6周组和固定期8周组与对照组相比各指标有显著性差异(P<0.05),而10周组与对照组之间各个指标对应均数无显著性差异(P>0.05)。结论:牵张后固定期10周时新生骨的机械强度已接近于正常下颌骨骨组织,固定期10周可能是较为适宜的牵张器拆除时机。

The Optimal Time Point to Dismantle the Distractor During the Mandibular Distraction Osteogenesis in Goats

Objective: To investigate the optimal time point to dismantle the distractor during mandibular distraction osteogenesis in goats. Methods: The right side mandibles of 12 goats were distracted after corticortomy, and divided into 3 groups in random. The first group was sacrificed at the 6th week of consolidation, the second group was sacrificed at the 8th week of consolidation, the third group was sacrificed at the 10th week of consolidation, and the left side mandibles of 4 goats from above were randomly selected as the control. The biomechanical properties of the new generation bone at 6th, 8th, 10th week of consolidation and the mandible of control group at the same time were detected by three point bending test and axial compressive test, and the changes of the biomechanical strength of the new generation bone during the period of consolidation were studied. Results: The biomechanical strength of the new generation bone increased with the pass of the consolidation time, the biomechanical strength of the 6th week group and the 8th week group showed significant difference with the control (P<0.05), but that of 10th week group showed no significant difference with the control (P>0.05). Conclusion: The biomechanical strength of the new generation bone at 10th week after distraction showed no significant difference with the normal, and the 10th week of consolidation may be the optimal time point for the distractor dismantled.