Objective To establish a three-dimensional finite element model of mandibular distraction osteogenesis （DO） in order to study the influence of distraction orientations to mandibular DO. Methods By using the two finite element models, Von Mises stress and the displacement under different loads were measured. Results The maximum stress in the distract equipment paralleled to the mandibular corpus was two times of that when the distract equipment paralleled to the sagittal axis. Von Mises stress concentration mainly occurred in the loading position and the condylar ante inferior. This phenomenon may lead to partial bone resorption, consequently lead to screw loose and affect the stability of distraction device. When the displacement increased in the model, the maximum stress and displacement showed linear relation. Conclusion The counterforce produced by the device makes lateral displacement in tail. The reaction force could be reduced to a minimum degree when the traction device parallel to the sagittal axis. This study provides theoretical basis for the position of distract equipment and distraction orientations in clinical application.
