Craniofacial displacement in response to varying headgear forces evaluated biomechanically with finite element analysis

Introduction: The aim of this study was to evaluate biomechanically the displacement patterns of the facial bones in response to different headgear loading by using a higher-resolution finite element method model than used in previous studies. Methods: An analytical model was developed from sequential computed tomography scan images taken at 2.5-mm intervals of a dry skull of a 7-year-old. Different headgear forces were simulated by applying 1 kg of posteriorly directed force in the first molar region to simulate cervical-pull, straight-pull, and high-pull headgear. Displacements (in mm) of various craniofacial structures were evaluated along the x, y, and z coordinates with different headgear loading. Results: All 3 headgears demonstrated posterior displacement of the maxilla with clockwise rotation of the palatal plane. The distal displacement of the maxilla was the greatest with the straight-pull headgear followed by the cervical-pull headgear. The high-pull headgear had better control in the vertical dimensions. The midpalatal suture opening was evident and was more pronounced in the anterior region. The articular fossa and the articular eminence were displaced laterally and postero-superiorly with each headgear type. Conclusions: The high-pull headgear was most effective in restricting the antero-inferior maxillary growth vector. Midpalatal suture opening similar to rapid maxillary expansion was observed with all 3 headgear types. The center of rotation varied with the direction of headgear forces for both the maxilla and the zygomatic complex. A potential for chondrogenic and osteogenic modeling exists for the articular fossa and the articular eminence with headgear loading.