骨欠損部再建プレートの生体力学的評価：有限要素解析

To evaluate, through three-dimensional finite element analysis (FEA), the stress and strain distribution in reconstruction plates of different thicknesses used for fixation of bone-grafted segmental mandibular defects.

A dentate mandibular model was obtained from computed tomography data and digitally processed for FEA using ANSYS 7.0. Three reconstruction plate models (2.0, 2.4, and 3.0 mm thick) were applied to simulate defects in the symphyseal, body, and angle regions of the mandible, each associated with block bone grafts and fixed using 2.4-mm locking screws. A 300-N vertical occlusal load and muscle vectors representing masticatory forces were simulated. Stress distribution was analyzed according to von Mises criteria across plates, screws, and bone graft blocks.

Increasing plate thickness reduced stress concentration within the plates but significantly increased stress on the fixation screws, particularly those adjacent to osteotomy lines. The symphyseal defect exhibited the highest stress values, followed by the body and angle defects. Stress values within bone graft blocks remained low (<250 MPa), indicating minimal deformation.

Thicker reconstruction plates enhance mechanical resistance but increase stress concentration on fixation screws, especially near osteotomies, suggesting a higher risk of screw loosening or peri-implant bone resorption. The anterior mandible demonstrated the most unfavorable stress distribution. Locking fixation systems are recommended when rigid plates are used to mitigate screw-related complications.