The Experimental Research Of Canine Mandiblular Defect Reconstruction By Curvilinear Distraction Osteogenesis

Mandibular defect is the most prevalent disease in oral maxillofacial surgery. It has played critical roles in oral functions and may severely influence life quality if the defect exists. In addition, it is also an important part of facial structure so that the defect may directly cause face abnormality. Although an acceptable mandibular reconstruction can be achieved in clinic now, the widely used materials such as autogenous bone graft and bone substitutes may produce other problems including large surgical trauma, donor site sacrificing and potential immunoreaction. Particularly the chin and angle area of mandible defects, which require curvilinear materials for reconstruction, have become one of the focuses in the reconstruction of maxillofacial surgery.Distraction osteogenesis(DO) has provided reliable support for bone defect repairment. It has been extensively performed in Cranial-maxillofacial deformities reconstruction in recent years and has become one of the focuses of maxillofacial defect reconstruction research. However, only the linear distraction is used in clinic, which is driven by screw rotation and not suitable for the chin and angle area defects. How to break through the screw torque limitation to realize curvilinear and even 3-D distraction needs to be solved in urgent.Our research is to confirm the curvilinear DO process by using internal distractor based on the steel ball conducted force. Based on our previous studies, the DO effect was performed in different animal models in order to provide some experimental clues for curvilinear DO.The study can be divided into two parts:PART ONE: Animal model establishment and distractor fabricationUnilateral rectangular canine mandibular body defect(~3 cm) was fabricated according to the curvilinear DO designation. The cranial data was obtained by CT scanning to make 3-D geometric model. The defect parameters were precisely measured to fabricate the individualized internal installed distractor based on the steel ball conducted force. The in vitro simulation was performed to confirm the effect and distraction track of the distractor.PART TWO: Experimental study of mandibular defect reconstruction by curvilinear distraction osteogenesisAccording to the previous part, the mandibular body defect was reconstructed by curvilinear DO. This part aimed to prove the osteogenesis effect of the internal installed distractor based on the steel ball conducted force. After DO process, the general observation, X-ray irradiation and histological evaluation were performed to assess the bone formation at different time points.The research demonstrates that:1. The rectangular canine mandibular body defect may be suitable for curvilinear DO research;2. The steel ball conducted force is stable and controllable. In vitro simulation and tract test have proven that it has reliable stability and effect, which has provided essential conditions for curvilinear DO research;3. volume optimized distractor complies with the requirement of DO and the structure is reasonable;4. The DO tract is in agreement with pre-designed tract. The curvilinear DO process is similar to linear DO process and can comply with the requirement of ideal osteogenesis;5. Cartilage ossification phenomenon exists in several DO areas and whether it is related to the distraction tract needs to be further validated.