Analysis of the degree of hydro-thermal fatigue damage of the surface layer of polymer-ceramic composites intended for operation in a biotribological node

The paper addresses the problem of assessing the operational quality of the surface layer (SL) of polymerceramic composites. These materials are used in conservative dentistry to reproduce geometrical features of human lateral teeth carrying the largest biomechanical loads. The chewing process causes that applications of these materials partly work in sliding friction conditions. Their durability in the biotribological node depends on the mechanical contact loads and is related to the influence of oral environment factors. In this study, we assessed the impact of cyclical hydro-thermal shocks, among others, related to the consumption of hot and cold food, on the condition of SL polymer-ceramic composites. In our own research, cyclic hydro-thermal shocks with cycle temperatures of 5–55°C were simulated. Evaluation of the remaining surface strength (after implementation of the hydro-thermal cycles) was made on the basis of microhardness measurements using the Vickers method. Calculations of the damage function value were made. It has been demonstrated that the durability curves depend on the number of fatigue cycles and the structure of the material. In addition, it has been shown that the phenomenological measure of SL damage, assuming accumulation of damage, is useful in the assessment of the operational quality of polymer-ceramic composites.