Numerical modeling of hyperfoam behavior of periodontal ligament in mechanical loading

This paper investigates the biomechanical response of the tooth and the surrounding tissues under a special type of the orthodontic loading. A 3D model of the upper left incisor of the human tooth is constructed. The periodontal ligament (PDL) is considered as a hyperfoam material and the other tissues are studied as elastic materials. The material properties of the PDL are determined by fitting the experimental stress-strain data of a lamb specimen to the hyperfoam constitutive equations. The goal of this study is to analysis the stress distribution under two loading conditions where the force magnitudes are set to 1N and 2N and they are applied in the mesial-distal direction on three different regions of the tooth crown. Results showed that by applying force to the tooth, the stress concentration is observed mostly on the mesial and distal sides. The maximum value of the compressive stress by the loads of 1N and 2N on the topmost point is 0.219MPa and 0.878Mpa, respectively. The tensile stress is detected on the mesial side where its minimum value by the loads of 1N and 2N on the topmost point is -0.069MPa and 0.307MPa, respectively. According to the results, the PDL absorbs the stress and prevents the large deformation of the alveolar bone. Results showed that the behavior of the tooth during the orthodontic loading reduces the possible injury to the tooth and bone tissues.