Optimizing titanium implant nano-engineering via anodization

Abstract

Electrochemically anodized titanium-based implants with controlled titania nanotopography enables enhanced bioactivity. However, anodization optimizations have been restricted to polished flat Ti foils, while clinical implants are often micro-rough with curved geometry. To enable anodization optimization of Ti implants, we performed short-time anodizations (10 s–600 s) on implant relevant micro-rough Ti wires (D: 0.8 mm) and rods (D: 5 mm) to understand the nanostructure self-ordering. We also studied the influence of electrolyte aging (repeated use of an electrolyte to tune its chemical balance) on implant anodization. Results revealed a higher electric field around Ti in aged electrolytes promotes the vertical elongation of nanotubes/pores. In comparison, fresh electrolytes established a lower electric field that limited the tube/pore elongation and caused cracks on the anodic film after an extended anodization time. We report an efficient implant nano-engineering protocol (PBR value of 2.7–3.0) for Ti rods (mimicking dental implants/abutments) via tailored anodization parameters. Further, reduced anodization voltage is proposed for anodizing Ti wires (mimicking orthopaedic fracture pins) to minimize excessive TiO2 dissolution. The current study evaluated nanostructure self-ordering on clinically relevant curved/micro-rough Ti, towards an improved understanding of implant nano-engineering.