[Three dimensional finite element analysis of stress induced by orthodontic forces in the periodontal tissue].

The purpose of this study was to investigate the stress induced in the periodontal tissue of the upper central incisor by application of orthodontic forces. A three dimensional finite element model consist of tooth, periodontal ligament (PDL), cancellous and compact bone was established and the following results were obtained: (1) The highest stresses were observed on the root surface, the intermediate on the alveolar bone and the lowest in the PDL. (2) Stress condition on the surface of root and alveolar bone is very complex. The maximum, intermediate and minimum principle stresses on the same area are quite different, but the three principal stresses in the PDL are similar. (3) Regarding to tipping and torque movement, the stress value varied largely from the cervix to the apex, and there is stress concentration at the cervix and the apex. For bodily movement when M/F is -10.30, the stress induced is homogeneous and the difference of the stress values from the cervix to the apex is little, which seems to be more physiological.