Design And Mechanical Analysis Of Mandibular Internal Fixation Based On 3D Printing

Mandibular repair technology involves cranio-maxillofacial repair surgery,mechanical engineering,and computer technology.It has a strong interdisciplinary feature of combining medical and engineering.It also needs to combine complex structure design and material research and development.Mandibular fractures and bone defects are generally caused by trauma,tumors,and congenital developmental defects and other diseases,which can affect the normal physiological functions of patients and cause facial deformation,chewing disorders,and mandibular joint disorders.3D printing technology is a technology that uses "digital model files（STL）" as the basis to manufacture objects in a "layer-by-layer manufacturing and layer-by-layer stacking" method.The development and maturity of selective laser melting technology（SLM）technology provides new ideas for the treatment of mandibular fractures and bone defects.Metal powder can be manufactured to obtain personalized porous bone implants and bone micro-plates.In this paper,the following jaws are the research objects,and the design,manufacturing,and mechanical properties of the jaws are studied.The main contents are as follows:1.Use SLM technology to print and manufacture personalized titanium plates and porous bone implants.The process parameter optimization scheme is designed based on the orthogonal experiment principle,and the process parameter group is calculated by finite element simulation software,and the stress and deformation of the formed part under different process treatment schemes are obtained.The process parameters are laser power100 W and scanning speed 1600 mm /s,the scanning distance is 0.12 mm,and the spreading thickness is 0.045 mm,which has the least influence on the stress and deformation of the formed part,which provides a reference for the optimization of SLM processing technology.Optimize the print manufacturing process,including pre-processing,print manufacturing and post-processing,and use the optimized process parameters and manufacturing process to print the finished product.2.The bone healing was studied based on the different materials of the fixed plate.The finite element models of mandible,bone plate,retention screw and callus were established to simulate the callus growth during the fracture period of mandible,healing for 4 weeks,8 weeks and 12 weeks.The stress distribution of bone plate and retention screw of different materials in the process of mandibular fracture healing was studied,and the callus strain was obtained.the material before bone healing 4 weeks had obvious effect on the mechanics of mandible and fixation plate.3.The width of personalized reconstruction plate and the biomechanical behavior of bone graft were studied.The appropriate width of reconstruction plate was selected by comparing the stress and displacement results of each model by finite element method.The results show that 4mm width reconstruction plate has good mechanical properties,which lays a foundation for the research and development of bone implant fixation with porous structure.Then the porous structure prosthesis model is established.According to the equivalent force values of different pore structures and the calculated elastic modulus values.the porous structure with good mechanical properties was selected for Boolean operation with fibula to obtain the porous bone implant model of mandible defect.In summary,this paper uses the characteristics of 3D printing technology to manufacture special structure,mandibular fracture and defect repair as an example,designed mandibular fracture fixation plate and mandibular defect porous bone implantation structure,using optimized SLM printing molding manufacturing.