Biomechanical Study Of Rigid Internal Fixation For Subcondylar Fracture Through 3D FEM Simulation

[Objective]Subcondylar fracture is a kind of common types of mandibular fracture, in the choice of operation treatment, the fixed way has no uniform standard, and there is no theoretical basis for guiding treatment. This experiment through the computer software to establish the subcondylar fracture of three finite element models were simulated in two kinds of rigid internal fixation, setting conditions after loading force, its mechanical analysis, comparison of the two stable fixation for Subcondylar choice sudden fracture fixation provide a theoretical basis.[Methods]1.To establish a three-dimensional model of the mandible:Select a complete dentition, molars, neutral occlusal relationship; anterior teeth overbite and cover normal relations; no history of orthodontic and orthognathic; no temporomandibular joint dysfunction syndrome health as an adult volunteer testers, gender did not ask. A CT scan of the head, based on the original CT data to 512x512 matrix export DICOM format and saved, model of mandibular three-dimensional with Mimics software and Geomagic software.2.To establish titanium plate and titanium screw fixation system of three-dimensional model:the use of SolidWorks Three-dimensional mechanical design software according to Kunming Huai Ying Technology Co. Ltd. Gift of Lorenz(?) midface panel 2.0mm screw system established titanium plate and titanium screw fixation system of three-dimensional model.3. Subcondylar fracture establish rigid internal fixation of three-dimensional finite element model:The use of Hypermesh software loaded titanium plate and titanium nail internal fixation system, and in accordance with the study were established two kinds of rigid internal fixation of the three-dimensional finite element model.4. Endow the three-dimensional finite element model of material properties: Use Hypermesh software reference material property data acquisition inquiries were endow to titanium-titanium screw fixation system and the mandible material properties.5.Finite element model of load stress analysis:According to the actual situation of boundary and masticatory muscle force loaded by the Abaqus software, the simulation of two kinds of occlusion(Anterior occlusion,Bilateral posterior occlusion), analysis of two kinds of fixation of fracture displacement and stress of titanium plate and titanium nail broken ends in stress loading conditions.[Results]1. Established 3D model of mandible and 3D solid model of titanium plate and titanium nail entity model, realistic shape, can be rotated to observe and measure the length and angle of the variety.2. Establish the Subcondylar fracture 3D finite element model with rigid internal fixation, mandibular ramus outer slope two miniplate fixation system consists of 201830 nodes and 96098 elements; mandibular ramus outer slope of a small plate fixation and posterior ramus of mandible of a mini plate fixation system is composed of 196850 nodes and 92435 elements.3. The state of stress distribution:mandibular ramus outer slope two miniplate fixation system, the biggest stress appear in the middle of the superior titanium plate, stress are respectively 339MPa and 278MPa; mandibular ramus outer slope a small plate fixed+mandibular ramus fixed trailing edge of a small plate system, the biggest stress appear in the middle of the superior titanium plate, stress are respectively 188MPa and 172MPa.4. Broken ends displacement situation:In the applied normal bite force, the mandibular ramus outer slope two miniplate fixation system, the broken end displacement are respectively 0.053mm and 0.042mm;mandibular ramus outer slope a small plate fixed+ mandibular ramus fixed trailing edge of a small plate system, the broken end displacement are respectively 0.024mm and 0.013mm.[Conclusions]1.Using Mimics software and Geomagic software to extract the target contour line, rapid modeling,3D model has a high geometric similarity, convenient and simple to operate.2. Using Three-dimensional mechanical design software SolidWorks, Hypermesh and Abaqus finite element software to establish the Subcondylar fractures Rigid internal fixation of three-dimensional finite element model, accurate and reliable, in setting boundary conditions can be carried out finite element analysis of resultant force loading.3. Two fixation methods were able to achieve the stability requirements of the mandible healing, mandibular ramus outer slope a small plate fixed + mandibular ramus fixed trailing edge of a small plate system is better than mandibular ramus outer slope two miniplate fixation system.