Surface Properties and Mechanical Performance of Ti-Based Dental Materials: Comparative Effect of Valve Alloying Elements and Structural Defects

Two approaches can be taken when designing properties of the native oxide layers formed on Ti-based biomedical materials: (i) changing the chemical composition of the substrate by adding biocompatible, valve alloying elements, and (ii) changing the microstructure of the substrate—especially its level of defectiveness—through large plastic deformation. However, especially in the aggressive fluoridated oral environment, it is still unknown what factor is more effective in terms of enhancing oxide layer protectiveness against biocorrosion: (i) the presence of valve alloying elements, or (ii) a high number of structural defects. To gain knowledge about the separate influence of both of these factors, surface properties were examined for commercially pure Ti and Ti–Nb–Ta–Zr alloy in microcrystalline state as well as after multiple-pass cold rolling, a process that can be readily scaled up to the industrial level. This study showed that while valve-alloying elements and structural defects individually have a beneficial effect on Ti oxide layer properties in fluoridated medium, they not have to act in a synergistic manner. These findings have to be taken into account when designing future Ti-based dental materials together with analyzing their mechanical performance with respect to mechanical strength and elastic properties.