Three-dimensional Finite Element Analysis For Reconstruction Of Human Mandible Segmental Defects By Curvilinear Distraction Osteogenesis

As an important section to maintain the facial profile and oral function, themandibular defect caused by a variety of reasons, will result in varying degrees oftopography damage and dysfunction. Because of mandibular special anatomy andfunction requirements, reconstruction of mandible defect has been a hot topic inthe field of Oral and Maxillofacial Surgery. In recent years, distractionosteogenesis (DO) technology which has been widely used in the field ofmaxillofacial surgery provide a new method to treat the mandibular defects anddeformities. Compared with traditional method, DO has incomparable advantages.However its use for curvilinear defects is limited. The three-dimensional curve ofthe maxillofacial bone requires an effective and stable way of transferringpressure that allows the surgeon to alter the vector of the distraction optimally. Inorder to find an effective way to transfer pressure during curvilinear distraction,our team has successfully invented a kind of internal sphericity distractor whichhas been used for repairing segmental chin defect in dogs. On this basis, this study tries to investigate the biomechanical characteristics and the stress changeof osseous tissue during the curvilinear distraction procedure, improve the designof curvilinear distractor and provide new biomechanical evidence for clinicalapplication through three diamensions-finite element of human mandiblesegmental defect model (established in the Mimics and Hypermesh software),.The research includes three parts:1Establishment of the three-dimensional finite element model of humanmandibleA male mandible was scanned by spiral CT and the Dicom format imageswere imported into Mimics and Hypermesh software, respectively.Three-dimensional finite element model of human mandible can be establishedby Mimics and Hypermesh. It will provide an artificial fundament for thebiomechanical analysis of human mandible.2Establishment of the three-dimensional finite element model of humansegmental mandible defectOn the basis of solid model of human mandible, the mandible between thebilateral first premolar was incised with the “cut” tool of Hypermesh software,and the separated mandibular was connected by simulated distractor. Then themodel was imported into Hypermesh again to mesh and make assignment.Finally, three-dimensional finite element model was established. It will providea biomechanical analysis fundament for reconstruction of segmental mandibulardefect by curvilinear distraction osteogenisis.3Three-dimensional finite element analysis for reconstruction of humanmandible segmental defects by curvilinear distraction osteogenesisAccording to the three-dimensional finite element model of humansegmental mandible defect, we designed the distraction plate on the right end, and then simulated the process of curvilinear distraction osteogenesis along theradian of simulated distractor (the radian of mandible before cutting). In thisprocess, Von Mises stress of osteogenesis track and displacement will bemeasured.Results：By means of establishment of different three-dimensional finiteelement model and mechanical analysis of curvilinear distraction osteogenesis,this study indicated that the newly formed mandible deviated to lingual and thecurvature of reconstructed human mandible was less than that of the normal. Thefindings suggest that we should consider the displacement factor in the design ofcurvilinear distractor.