矢狀分割骨折斷術 後 나사固定方法에 따른 應力分布에 관한 有限要素法的 硏究

A finite element study of stress distribution on screw fixation after sagittal split ramus osteotomy

A finite element study was done for stress distribution on various rigid fixation methods with screw after sagittal split ramus osteotomy. The purpose of this study was to analyze the various methods used for screw fixation after sagittal split ramus osteotomy. The fixtation methods were classified as the Type I-triangular pattern at 90 degree to the bone surface(2 above and 1 below the mandibular canal), Type Ⅱ-triangular pattern at 70 degree to the bone surface (2 above and 1 below the mandibular canal), and Type Ⅲ-linear pattern at 90 degree to the bone surface (3 above the mandibular canal). Also the applied direction of force was classified as the anterior, premolar, and molar area with 100Kg F/㎠ on each region. The results were as follows: 1. The stress was mainly concentrated on the condylar neck of the mandible and the superior area if proximal bone fragment after sagittal split ramus osteotomy with screw fixation. 2. The stress acting on the screw was principally shear stress, which cause the screw to bond, and increased in magnitude as the applied force was moved from posterior to anterior, and increased in angulated case than perpendicular case. 3. The triangular patterm was clinically more favorable compared tot he linear patterm, because the stress distribution on the screw was comparable uniform, and inferior screw significantly contributed to prevent the screw bending. 4. The perpendicular pattern to the bone surface was clinically more favorable than the angulated pattern, because the actual differences of shear stress on the screw was increased as the applied force was moved from posterior to anterior.