Abstract
The purpose of this study was to evaluate the Shaping of the Mandibular Path during the Occlusal Phase of Mastication. We have previously developed a new computer simulation method for calculating the shearing strain energy in a model of food as an index for detection the energy of occlusion, and this method allowed us to suggest that the occlusal condition could be evaluated using this index. The aim of this report was to verify the hypothesis that the path of the masticatory stroke is shaped to enhance the efficiency of food breakdown. The below-mentioned method was done as follows;
1. Twelve spatial (bucco-lingual and vertical) relationships between maxillary first molar and second premolar, and mandibular first molar were set up for the occlusal phase of mastication. At each relationship, models of teeth and food were made by CAD, and FEM was applied to each model in order to calculate the shearing strain energy in the model of food. For loading, the direction of the masticatory muscle's action was decomposed into its horizontal and the vertical components related to the occlusal plane, and the force for 0.01mm displacement was given to each direction.
2. The ratio of the shearing strain energy in the model of food (P) was calculated by dividing the horizontal load by the vertical load.
Results:
1. During the path of closure, P became higher in all bucco-lingual relationships.
2. As the mandibular first molar moved from the working side into the intercuspal position, the change rate of P increased accordingly.
In conclusion, these results imply that the horizontal component of the path of mastication increases during the occlusal phase in order to enhance the efficiency of food breakdown.
