Surface Characterization of Titanium-Based Substrates for Orthopaedic Applications

Orthopaedic implants for load-bearing applications are usually composed of titanium-based materials. Aiming to propose a strategy able to improve the bone-implant interface on these implants, commercially pure titanium and Ti6Al4V alloy were subjected to anodic oxidation, hydrothermal treatment and to anodic oxidation followed by hydrothermal treatment and the produced oxide film was investigated. In addition, different mechanical (as-received vs mechanical polished) and chemical pre-treatments (alcohol cleaning vs acidic pre-treatment) were studied. No significant differences were found between the chemical pre-treatments, whereas upon different surface treatments the TiO2 layer presented different characteristics, namely regarding its crystallinity, roughness, thickness and wettability. The hydrothermal treatment followed by immersion for 24 h in 5XPBS was effective in creating a potentially bioactive oxide film, given the presence of anatase and rutile phases, and a hydrophilic layer for both Ti materials. Ti grade 2 subjected to alcohol cleaning and hydrothermal treatment resulted in a surface roughness of 226.7 +/- 3.1 nm and water contact angle of 67.2 +/- 8.7 degrees, whereas for the Ti grade 5 subjected to the same surface treatment, Ra was equal to 20.4 +/- 1.7 nm and the water contact angle to 83.5 +/- 4.7 degrees. In this context, the hydrothermal treatment is proposed as a simple treatment capable of improving the characteristics of the implant surface, thereby promoting osteoconductivity.