Effect of the structure and hydrothermal conditions on the strength of polymer-ceramic composites

Abstract Polymer composites properties depend on their structures. Good initial properties are often not enough because they change under environmental conditions. Thus studies of functional properties should provide information about both, their initial properties and their behavior under operating conditions. The aim of the study was to determine the effect of the structure of dental composites and the environmental hydrothermal conditions on their mechanical strength. Light cured polymer matrix ceramic composites (LC PMCCs) were investigated. Commercially available composites and experimental materials with different contents of filler particles were tested. Compressive strength, three-point and biaxial flexural strength tests were carried out. The tests were performed using composites without a load history, composites exposed to a moist environment and to hydrothermal aging. In most cases, changes in compressive strength under the effect of the moist environment and hydrothermal aging were non-significant. Values of compressive and three-point flexural strength obtained for universal type materials were higher than those obtained for flow type composites, while the latter were characterized by higher values of biaxial flexural strength. Hydrothermal aging caused the greatest decrease (approx. 60%) in the three-point flexural strength of universal type composites. The strength degradation of flow type materials was about 40%.