Finite element analysis of the equine periodontal ligament under masticatory loading

The finite element method (FEM) is a highly approved method to simulate biophysical phenomena in computerized models of teeth and their periodontium. In human dentistry, the FEM has been used most fruitfully in the fields of restorative dentistry and prosthodontics. The introduction of FE-simulations in the field of equine dentistry requires a multiple step process which includes work from various disciplines. Data sets from micro-computed tomography (mu CT) were used for the 3-dimensional reconstruction of a computerized model of an equine mandibular molar together with its supporting tissues. Considering the distinct dental anatomy of the horse, special attention was paid to reconstruct individual, 3-dimensional models of each of the dental hard substances, the pulp cavities, the periodontal ligament and the alveolar bone. These models were assembled in a complete 3-dimensional model of the tooth and its surroundings. In a further step, volume models were generated and tooth movement during different masticatory actions (closing stroke, power stroke) was simulated by means of FEM. Boundary conditions for the masticatory actions were taken from previous force measurement experiments. Masticatory loads caused a distinct spatial pattern of tensile and compressive stresses in the periodontal ligament. Visualization of von Mises stresses demonstrated stress concentrations in the vicinity of the delicate tips of the dental roots and in the subgingival area. For the first time an FE-analysis was performed to analyze biomechanical effects in the equine periodontal ligament under masticatory loads. The elaborated FE-models will allow designing continuative clinical studies to analyze biomechanical effects also in the dental hard substances. Such studies will provide data to answer current questions in the fields of equine dental etiophatology, dental restorative therapies and prophylactic treatments.