A 3D-FEM Study On Stress Distribution And Displacement Of Nasomaxillary Complex Following Application Of Posteriorly Directed Orthopedic Forces

Objective To investigate the relationship between the displacement and stress in the nasomaxillary complex and the direction and the position of the distallly-directed orthopedic forces, and to search the optimal load pattern when inhibiting the growth of the maxilla in clinical.Methods Using SCT image reconstruction technique, digital image transfer,image transcription,3-D FEM in combination with AutoCAD2004, unigraphic and MSC.Marc software., a 3-D finite element model of nasomaxillary complex of a normal twelve years old boy was established. Then twelve different load patterns were added , and stress distribution of nasomaxillary complex and 3-D displacement of temporo-zygomatic suture, naso-frontal suture, zygomatic-maxillary suture, fronto-maxillary suture were analyzed.Results 1)A 3-D finite element model of nomal nasomaxillary complex was constructed, including 69366 elements and 34344 nodes. 2) The stress distributions of nasomaxillary complex coincided with the trend of the maxilla's three couples of brace struts after twelve different load patterns were added. 3) Different load patterns led to different stress distributions and displacement. The distallly-directed orthopedic force parallelling to the occlusal plane was indicated to be the most effective pattern to inhibit the maxilla's growth. 4) It was indicatad that after the twelve different load patterns were added the maxilla moved downward and backward and rotated in clockwise sense ,and the amount of rotation were increased gradually as the downwards component of forces were larger. Conclusions The force direction determined the stress distributions and displacement of nasomaxillary complex and sutures. The direction of displacement did not strictly coincide with that of the applied force.