Design of Customised Orthodontic Devices by Digital Imaging and CAD/FEM Modelling

In recent years, the public demand of less invasive orthodontic treatments has led to the development of appliances that are smaller, lower profile and more transparent with respect to conventional brackets and wires. Among aesthetic appliances, removable thermoplastic aligners gained instant appeal to patients since able to perform comprehensive orthodontic treatments without sacrificing comfort issues. The aligner must deliver an appropriate force in order to move the tooth into the expected position. However, at present, the relationship between applied force and aligner properties (i.e., aligner’s thickness) is poorly understood. In this paper, a patient-specific framework has been developed to simulate orthodontic tooth movements by using aligners. In particular, a finite element model has been created in order to optimise the aligner’s thickness with regard to the magnitude of the force-moment system delivered to a mandibular central incisor during bucco-lingual tipping.