[Stress analysis of the periodontal ligament of the human tooth using a three-dimensional finite element method]

Three-dimensional finite element analysis is used to determine the physiological stress values in periodontal ligament (PDL). In comparison with the elastic modulus E of PDL, the E of dentin and bone are much larger. For the estimation of the stresses in PDL, the tooth and the supporting bone can be considered to be rigid. The finite element model of PDL of the mandibular right first molar consists of 210 elements (20-node isoparametric element) and 1612 nodes. Eleven load cases were selected in the study, which included the longitudinal occlusive load, buccal lingual lateral load, mesial-distal lateral load and other load cases to simulate the actual occlusive loads. The results obtained from this study lead to the following conclusions: 1. The loads which go through the physiological center of the tooth, the stresses induced by the loads which are compressive and relatively small. There are no tensile stresses. 2. Among eleven load cases studied in this work, the following three load cases are most harmful. a. The maximum tensile stress was found under mesial-distal lateral load; b. The maximum compressive stress was found under longitudinal occlusive load on the buccal groove or lingual groove; c. The highest stress concentration was found under buccal-lingual lateral load. The clinical significance of the results has also been discussed in the paper.