Initial stress induced in periodontal tissue with diverse degrees of bone loss by an orthodontic force: tridimensional analysis by means of the finite element method.

This study was undertaken to determine the stress that appears in tooth, periodontal ligament and alveolar bone, when a labiolingual force of 100 gm is applied in a labiolingual direction in a midpoint of the crown of an inferior digitalized canine, and its changes depending on the degree of loss of the supporting bone. The analysis of tensions was carried out by means of the finite element method (FEM) for a normal case and after reducing the periodontal support bone 2, 4, 6, and 8 mm. Three-dimensional images in false color in which intensity of tensions and its areas of extension are generated. Special attention was paid to changes at level D (apical transversal section) to which maximum, mean, minimum, and Von Mises tensions are calculated. After applying the labiolingual force in the canine, a progressive increase of the stress in the labial and lingual zones of the tooth, periodontal membrane and alveolar bone was observed when the alveolar bone was reducing. In the mesial and distal zones, no compensating forces appear, which could provoke a tooth rotation during the tipping movements.