颧骨内置弧形牵张成骨器修复部分上颌骨缺损的可行性

背景:由于骨性支持缺乏,上颌骨大型缺损功能性修复是一项很困难的工作,现通过动物实验阐述并考察一种上颌骨缺损部分修复,重建骨性支持的新方法。目的:考察以自行研制的骨牵张器进行颧骨内置弧形牵张成骨修复部分上颌骨,重建骨性支持的可行性。设计:观察性动物实验。单位:解放军第二五二医院口腔科。材料:选用健康杂种犬2只,雌性,犬龄1～1.5岁,体质量20～25kg。颧骨内置弧形骨牵张器由三部分组成:弧形轨道、滑块、轨道中央的柔性中心螺杆,前两者由钛合金制造,中心螺杆由超弹性钛镍合金丝制造,每旋转1周,滑块移行0.35mm,最大牵引距离为25mm。方法:实验于2003-10/2004-02在解放军第四军医大学动物实验中心完成。在犬上颌骨、颧骨区域制作宽18～20mm节段性缺损,模拟上颌骨缺损,然后截骨制作骨转移盘,安置骨牵张器,实施颧骨内置弧形牵张成骨,术后第5天开始以1.05mm/d(0.35mm/次,3次/d)的速率加力牵引,连续13d。在牵引前,牵引结束时,固定期2,4,8周时,以颧骨、颧弓位X射线平片对成骨过程进行观察。主要观察指标:实验动物及骨牵张器大体状况及新骨生成效果。结果:实验内容均按计划完成,X射线平片示,牵引结束时,骨移动盘实现显著的改向、内旋,弧线式牵引约12mm,固定期8周时,各观察项目显示,新生骨骨质密度接近正常,与双侧正常骨质连续,弧线完整平滑,颧骨弧线式牵张成骨基本完成。结论:自行研制的骨牵张器由于其弧度适应于上颌骨、颧骨区域,具有应用于颧骨内置弧形牵张成骨修复部分上颌骨的可行性。

Feasibility of internal curve distractor of the zygoma for maxillary segmental reconstruction

BACKGROUND:The functional reconstruction of large maxillary defects is a significant challenge due to the lack of bony support.In this paper.a new approach for segmental maxillary reconstruction and bony support foundation is put forward and tested by animal experiment.OBJECTIVE:To evaluate the possibility of segmental maxillary regeneration by internal curve distraction osteogenesis of zygoma with the self-developed distractor.DESIGN:Animal experiment.SETTING:Department of Stomatology.the 252 Hospital of Chinese PLA.MATERIALS: Two healthy female hybrid canines of 1-1.5 years old and 20-25 kg were selected. Internal curve distractor was composed of three parts:curve track,movable part and a flexible central thread bar fixed at the center of the curve track.The former two parts,which was made of TC4,(Ti-6AI-4V),and the flexible central thread bar was made of nickel titanium wire. A 360° of counter clockwise rotation of the distraction activator achieved an advancement of 0.35 mm for the movable part;the maximum distraction length allowed by the distractor was 25 mm.METHODS: The experiment was carried out in the animal experimental center of Fourth Military Medical University of Chinese PLA from October 2003 to February 2004. The segmental defect of 18-20 mm in width was made in maxilla and zygoma to simulate maxillary defects.Then an osteotomy distal to the defect was performed to create the variable transport disk. The distractor was fixed to the residual zygoma and zygomatic arch for internal curve distraction osteogenesis.After a latency period of 5 days,the distraction started at a ratio of 1.05 mm per day (0.35 mm once,3 times per day) for 13 consecutive days. Before and after distraction and at the second, fourth and eighth week of consolidation, the bone radiographs of residual zygoma and zygomatic arch were taken routinely.MAIN OUTCOME MEASURES: The general condition of the animals and distractor, and the quality and quantity of new formation bone in the distracted gap.RESULTS:Canines and distractor were in good condition during the experimental period.X-ray film showed that at the end of distraction, the bony transport disks were distracted about 12 mm around arc.At the 8th week of consolidation,the density of new bone was close to that of normal bone,and the curved bony regeneration was almost completed.CONCLUSION: The serf-designed curve internal distractor is fit the condition of major maxillary defects,and could be used for the internal curve distraction of zygoma.