Evaluation of roughness and electrochemical behavior of titanium in biological environment

The increasing use of titanium in the biomedical field arises from the excellent biocompatibility due to the ability to spontaneously become covered with a passive layer. Several studies have shown that some surface treatments can enhance the biological response and corrosion resistance of the implants. The aim of this work is to study the effect of surface treatments of sandblasting and etching with HF on the electrochemical behavior in biological environment and on the roughness of two types of commercially pure titanium, Ti grade 2 and Ti grade 4, used for prostheses and dental implants. The electrochemical characterization has allowed showing that the passive current density increases with the duration of the sandblasting treatment for both alloys. A smaller increase was found in samples subjected to blasting and subsequent etching. It follows that the variation of specific surface induced by blasting is partially canceled by the chemical treatment. The value of passive current density was used to assess the extent of the increase of the real surface of the samples. The roughness analysis showed that the blasting process produces a surface with a large number of peaks, and that the etching with HF tends to level the surface attenuating peaks. The sandblasting and etching treatments, alone or combined, significantly modify the surface of the samples and the magnitude of this change differs depending on the alloy used. Finally, it is proposed to use four roughness parameters to characterize the treated surfaces.