The Experimental Study For The Segmental Reconstruction Of Maxilla Loss By Distraction Osteogenesis Of Zygoma

The maxilla is the functional and aesthetic keystone of the midface. The patients suffer a lot from its loss. But maxillary reconstruction has posed a significant challenge because of the complex anatomy and neighborship . Nowadays , the maxillary prostheses are still the main modality for the reconstruction of the maxilla before the development of more sophisticated techniques .However ,how to achieve enough retention and support is the biggest problem in the reconstruction . In the condition of unilateral maxilla loss, only the ? residual tissue of healthy side is available for limited retention and support. The prostheses are liable to sink and turnover with the result of nerghboring tissue damaged .When bilateral maxilla lost ,the situation would be more worse. To overcome it, the clinicians apply the osseointegrated implant technique to the zygoma region .The employment of implants in the zygoma region provides good basis for the retention and support of maxillary prostheses . Nevertheless, because of zygoma' high position, the implants are always deep into the defect cavity with the disadvantage of difficulty of cleaning ,and prostheses are inconvenient to be takenand removed .Even Worse,the implants could only be put into the zygoma inclinedly ,the axis of it could not be unanimous to the occlusal force. So the occlusal force would act on the implants laterally, the peri-implant bone might be injured because of long term lateral force. However, if the technique of craniofacial distraction osteogenesis could be used to stretch the remained zygoma forward and downward to reconstruct the part of lost maxilla, the bony support could be set up ,and also, the implants could be applied in more suitable direction .On this basis, the mastication function reconstruction might be achieved better.The area of connection of zygoma and maxilla takes on a curved structure. So ,to reconstruct maxilla as possible,the zygoma should be distracted around an arc.The key of the success is the distractor.However ,most distractors used today are straight type, only straight distraction osteogenesis could be completed by them. Although ,some kinds of arced distractors have been invented and used ,they are usually external types and serve for DO of mandible.No one is suitable to zygoma. So,a new kind of internal arced distractor which could be applied to zygoma was designed and manufactured by ourself .The device was tested through animal experimental research and the vitro imitation on the dry human skull specimen.The research comprised of four part. Part I, The experimental animal model of DO of zygoma for the segmental reconstruction of maxilla loss was established to decide the way of DO of zygoma and test the feasibility of it; Part II, The animal experimental study of internal straight DO of zygoma for the segmental reconstruction of maxilla loss was performed. In the process of DO and after the specimen taken, the distracted areas were evaluated by general observation radiography histologic study SEM and BMD analysis to test and verify the feasibility and regularity of the DO of zygoma, and to investigate the effect of...