Mathematical modelling of biomechanical behaviour of the removable dental prosthesis basis under the characteristic chewing loads

In this work, we consider the issue of mathematical modelling of the biomechanical response of the removable lamellar prosthesis basis to external loading due to chewing load, from the moment of biting of food in the area of incisors to the final formation of a food dot in the area of molars. For this purpose and uniform presentation of the calculation results, for upper and lower lamellar prosthesis, at complete absence of teeth, the associated physically-based boundary conditions are selected. Modelling of the mucous membrane is carried out within the framework of the concept of an elastic foundation. However, for each of the considered prosthesis bases, its own morphologically substantiated features of the deformation behavior of the mucosa are introduced. In the case of the upper prosthesis basis, such a feature is the presence of a torus region; for the case of the lower prosthesis basis - the key role has the alveolar process. In the work, the stress-strain state is simulated in the bases of the upper and lower prostheses with symmetric and asymmetric loading on the main blocks of teeth: block 1 - incisors, block 2 - canine, block 3 - premolars, block 4 - molars. The value of the external load for each of the blocks is calculated based on the values of the characteristic muscular effort of the maxillofacial apparatus. The issues of setting individual blocks of teeth, the effect of their displacement relative to the recommended line of installation and slopes on the stress-strain state of the prosthesis base are investigated. A qualitative and quantitative comparison of the maximum stress fields and their spatial distribution is carried out for various configurations of installing tooth blocks and types of loading. The work shows that asymmetrical loading is the most dangerous from the point of view of the structural integrity of the prosthesis basis. Potential destruction of the denture basis can occur due to regular loading of the first two blocks of teeth. The factors that contribute to a reduction in the service life of the removable prosthesis basis under typical chewing loads have been identified.