Effect of artificial saliva on the mechanical properties of a polymer material reinforced with fiber, used in esthetic tooth restorations

Background. The oral environment can negatively affect the physical properties of fiber-reinforced composite (FRC) materials, which can lead to the deterioration of mechanical stability and reduce the span of their clinical usefulness. Objectives. The aim of this study was to determine the influence of artificial saliva on the selected mechanical properties of FRC. Material and methods. The core of the polymer material selected for the study was a bundle of ultrahigh-molecular-weight polyethylene (UHMWPE) fibers. Fourteen samples were stored in an incubator at 37 degrees C, in 20 mL of artificial saliva solution, and weighed on days 1 and 28. At the same time, mechanical tests were performed, including the measurements of Young's modulus, tensile stress, maximum tensile force, and tensile deformation. Results. The analysis of basic statistics together with the results of the Shapiro-Wilk test and the distribution of Spearman's rho coefficient showed a strong negative relationship between the pair of variables - tensile deformation and the sorption of synthetic saliva. The results related to Young's modulus of elasticity and tensile stress were not statistically significant. Conclusions. Water penetration into the space between the fibers does not adversely affect the mechanical properties of the material tested. In the static tensile test, high and desired mechanical strength was observed, which may justify the effective use of this type of material in clinical practice and may be a good alternative to prosthetic restorations, whose retention is obtained only through a mechanical connection with the abutment tooth.