| ObjectiveMandibular Angle Fracture is familiar, but the fixed mode is controversial. The most familiar clinical methods are tension band fixation and two-miniplate fixation. In this experiment, we want to develop a 3D FEM, and to observe the stress distribution of angle-fractured mandible under different rigid internal fixation (RIF) methods, and to supply theory evidences for how to choose RIF methods.Methods1. To establish the human mandible and the fixed-system 3D model:Select an occlusion of normal adult volunteer, to slice spiral CT scan, CT scan image based on the original data, using reverse engineering software Mimics establish the human mandible and the fixed-system 3D model.2. To establish the mandibular angle-fractured mandible under different RIF methods of 3D FEM:using FEM software MSC.Patran to establish a 3D FEM of human mandibular angle fracture, and fix the fixed-system on the mandible.3. Observe the stress distribution of different methods:Under the standard mandibular angle fracture, bilateral molar biting and four pairs of muscles loading, using software MSC.Marc to observe the stress distribution of different methods.Results 1. Mimics software modeling is rapid, convenient and simple, build the titanium plate mandibular reconstruction of three-dimensional model has good mechanical geometric similarity and similarity, for the establishment of finite element analysis of the three-dimensional finite element basis.2. Architecture of the human mandible and mandibular defects plate finite element model of human mandible reconstruction.Normal human mandible by the nodes, elements.3. The vons Mises stress distribution:plate strain were calculated for bite forces applied on INCisors,fracture side and non-fracture side, in the tension band fixation, the biggest stress appear in the middle of the titanium plate, in proper order, the figures are 83MPa(LMOL),44MPa(INC),133MPa(RMOL) and 172MPa(ICP); in the two-miniplate fixation, the biggest stress appear in the middle of the superior titanium plate, in proper order, the figures are 136MPa(LMOL), lOlMPa(INC), 140MPa(RMOL) and 174MPa(ICP).4. Fracture mobility:fracture mobility were calculated for bite forces applied on INCisors,fracture side and non-fracture side, in the tension band fixation, the furthest mobility is 0.31mm(RMOL); in the two-miniplate fixation, the furthest mobility is 0.091mm(LMOL).5. in the tension band fixation, when the biting force drop to N, the furthest fracture mobility get into margin of safety.Conclusions1. Mimics software modeling is rapid, convenient and simple, build the titanium plate mandibular reconstruction of three-dimensional model has good mechanical geometric similarity and similarity, for the establishment of finite element analysis of the three-dimensional finite element basis.2. The spiral CT scan and Mimics based on three-dimensional reconstruction of the human mandible reconstruction of three-dimensional finite element model of plate, practical and reliable, can be used for a variety of finite element analysis of working conditions.3. In the mandibular angle fracture, under working bite relation, the tension band fixation is amphibolous; the two-miniplate fixation is stable.4. In the tension band fixation, bite forces on INCisors and non-fracture side are safer.5. Choose the suitable dental occlusion, when the bite force drops to proper level, the tension band fixation becomes safe too. |
