A preliminary investigation on the effect of alloying elements on the bioactivity of titanium-based alloys

Titanium-based biomedical alloys are commonly preferred as implant materials in bone tissue applications owing to their advantages, such as their low density, superior corrosion resistance, and mechanical properties. However, osseointegration, which means ensuring the structural and functional bonding at the bone-implant interface, is a feature that still needs to be improved for titanium-based alloys. Among the surface treatments applied to titanium and its alloys to improve osseointegration and bioactivity, which is an indicator of bone tissue adhesion, alkali treatment is a prominent surface modification method due to its cost-effectiveness and practicality. Several studies have focused on the effects of modified alkali and heat treatment combinations on the bioactivity of Ti and its alloys. However, limited studies exist investigating the effects of alloying elements on the bioactivity of alkali and heat-treated titanium and its alloys in the literature. Therefore, in this study, the effects of alloying elements on bioactivity were investigated on alkali and heat-treated CP-Ti, Ti-6Al-4V, and Ti-6Al-7Nb. Alkali treatment was performed in 2M NaOH at 37°C for one week, followed by heat treatment at 600°C for one hour. Static immersion test results, conducted in triple-concentrated SBF, demonstrated that the CP-Ti surface was covered more rapidly with calcium phosphate than its alloys. On the alloy’s surfaces, sodium chloride salts precipitated, serving as an indicator of calcium phosphate formation. The distinct morphological structures formed on the alloy’s surfaces influenced the ionic exchange in SBF. Additionally, it is suggested that varying oxide layers could create diverse surface energy sites affecting bioactivity.