In vitro validated finite element method model for a human skull and related craniofacial effects during rapid maxillary expansion.

This paper presents the biomechanical effects on the craniofacial complex during rapid maxillary expansions (RME), by using an in vitro experiment compared with a three-dimensional (3D) finite element model of a human skull. For this purpose, a dry human skull with artificially constructed teeth was used. In addition, a 3D finite element model including the craniofacial sutures was developed based on computed tomography (CT) scans. Initially, two types of models were analysed. In the first model, the total activation of the jackscrew device was applied in one step. In the second model, more steps were applied, taking into account the phenomenon of stress relaxation during RME treatment. Afterwards, a parametric analysis of the finite element method model was performed using three more models in order to evaluate the influence of craniofacial sutures. Both in vitro and finite element results refer to the openings of four critical points (MI, UM, EM, and CN) on the left and right maxilla. Results show that the maxillae open in a pyramidal shape and that the degree of sutures ossification influences the displacement distribution on the craniofacial complex much more than the phenomenon of stress relaxation. The areas of the maximum stresses and displacements were also determined.