AZ31镁合金在垂直牵张犬下颌骨成骨的初步研究

A pilot study of vertical mandibular distraction osteogenesis using AZ31 magnesium alloy on dogs' mandible

目的初次探讨自行研制的可降解AZ31镁合金牵引器在牵张成骨中下颌骨的成骨情况和材料的降解性、生物安全性。方法采用12只杂种犬为实验动物。截骨术前3个月拔出12只犬单侧3颗磨牙。然后,12只犬均行一侧下颌骨截骨术,安置自行设计的镁合金和不锈钢牵引器。经5 d间歇期后,两组以0.3 mm/8 h的速度牵张7 d进入固定期。固定期4周处死12只动物,标本进行牙槽骨垂直向高度测量、扫描电镜观察、组织学观察以及肝、肾病理切片观察。结果牙槽骨垂直向高度:实验组平均增加(6.300±0.018)mm,对照组平均增加(6.307±0.027)mm,无显著性差异(P>0.05)。两组牵张间隙中均可见活跃的成骨细胞和骨小梁结构,以及少量成熟的骨组织。镁合金表面有较明显的腐蚀产物。实验组肝、肾病理观察结果均未见异常。结论自制ZA31镁合金牵引器在牵引完成后4周可提高下颌骨的高度,且骨质生成良好。镁合金在下颌骨内有一定的降解速度。镁合金对肝脏和肾脏无毒性作用。

Objective To investigate blone formation,material＇ s degradability and biological safety using self-designed degradable AZ31 magnesium alloy distractor on mandibular distraction osteogenesis（DO）.Methods 12 mongrel dogs were used in this study.Unilateral three odontoprisis were moved out 3 months before mandibular osteotomy.Then,unilateral mandibular osteotomy was performed on 12 dogs.By operation,self-made magnesium alloy and stainless steel distractors were implanted.After 5 days＇ latency,the dogs in two groups underwent distraction at the rate of 0.3 mm /8 h for 7 days and entered into consolidation period.12 dogs were respectively sacrificed at the fourth week after consolidation.Vertical height measurements of mandibles,scanning electron microscopy（SEM）,histological and liver-kidney pathological evaluations were performed,but nothing abnormal was detected.Results The segments in alveolar direction were augmented（6.300 ± 0.018） mm in experimental group and（6.307 ± 0.027） mm in control group.There were no obvious differences（P〈0.05）.Active osteoblasts,trabeculae and a little mature bone tissue gradually formed in distraction space of two groups.There were obvious cracks on surfaces of the magnesium alloy.There were no abnormalities in the pathological analysis of liver and kidney tissue in experimental group.Conclusions It suggests that four weeks after distraction with AZ31 magnesium alloy distractor,the height of mandibular has been increased and an adequate bone has been created.AZ31 magnesium alloy has a certain degradation speed in mandibles.AZ31 magnesium alloy has not any negative effect on liver and kidney tissues.