하악골 우각부 골절시 교합력에 대한 소형금속판 내고정의 삼차원적 응력 해석

Three-dimensional stress analysis of the miniplate fixation to the occlusal force for the mandibular angle fracture

The purpose of this study was to investigate the stress distribution and the displacement to the occlusal force in the intact mandible and in the angle fractured mandible fixed with miniplate at the upper and lower border. X, Y, Z-directions of force(10kg) were applied on the right and left mandibular first molar unilaterally. Material property, geometry, and load conditions of each model were inputed to the three dimensional finite element program and the stress distribution and the displacements finite element program and the stress distribution and the displacements were analyzed. The results obtained were as follows: 1. In the intact model, stresses were evenly distributed along the external oblique ridge of mandible. On the opposite side. Low level stresses were distributed along the external oblique ridge and coronoid process and maximam principal stress was observed at the load applied teeth. 2. In the cases of fractured model, higher level stresses were observed than those of intact model and maximam principal stress was observed on the miniplate when the load was applied at the left first molar. In cases of load applied at the left first molar maximam principal stress was observed on the load applied tooth in model of internal fixation on external oblique ridge and in cases of load applied at the right first molar maximam principal stress was observed on miniplate model of internal fixation on inferior border 3. In the cases of internal fixation with miniplate on the external oblique ridge, stress distribution was similar to those of intact model and displacement was smaller than that of internal fixation on the mandibular inferior border. 4. In the cases of internal fixation with miniplate on the inferior border, stress was distributed along the inferior border, being different form those in intact model. 5. In three type models, highest stress-concentration was observed under the vertical(Z) directional load and relatively stable results under inner(X) directional load on the fracture side first molar. Under load applied on opposite first molar, results were similar in three type models. These results suggest that stress distribution of internal fixation with miniplate on the external oblique ridge is more similar to intact model than internal fixation with miniplate on the inferior border with less displacement and internal fixation with miniplate on the external oblique ridge is more stable fixation method.