Background: As titanium (Ti) alloys are bioinert, various chemically-modified Ti surface has been developed to promote bioactivity and bone ingrowth.
Objective: In this study, various post treatments (water aging, hydrothermal, and heat treatments) were applied to NaOH-treated Ti-5Si to improve its bioactivity.
Methods: The bioactivity of surface-modified Ti-5Si was access by using the apatite formation ability of Ti-5Si surfaces soaking in a simulated body fluid (SBF).
Results: The results showed that the NaOH-treated surface formed a porous network structure composed of sodium titanate hydrogel, which was changed to sodium titanate after subsequent post treatments, whereas sodium titanate, anatase and rutile phases were found on the Ti-5Si surfaces after heat treatment. After immersion in SBF for 14 days, compact apatite layers were observed on the surfaces of all the Ti-5Si tested. The results of XRD and FTIR indicated that the apatite deposited on the Ti-5Si substrate with various surface modified conditions was carbonate-substituted hydroxyapatite.
Conclusions: The apatite-forming ability of the surface of the Ti-5Si was excellent, even though Ti-5Si was not subjected to surface modifications. As a result, the bioactivity of Ti-5Si alloy was verified by the apatite-forming ability, making it suitable for use in orthopedic and dental implants.
Keywords: Titanium alloy; alkali treatment; apatite; post treatment; simulated body fluid (SBF).