A mathematical model for the computation of the forces exerted by the facial orthopedic mask

This study presents a model for the computation of the forces exerted on the chin and on the forehead by the facial orthopedic mask in skeletal Class III malocclusions. Cephalometric data as well as geometry of the mask are taken into account to simulate in quantitative terms the entire approach. A computer program has been implemented to validate the model on a group of patients. Despite the approximations about the mechanical characteristics of the appliance and of the constraints (rigid body, ideal constraints) and despite the unavoidable errors in the estimation of the geometric parameters (dimensions and angles), it is shown that the computation of the forces (in orientation and in magnitude) at the forehead and at the chin is possible. Some practical applications of the model are presented.