Dual-layer biphasic calcium phosphates/tantalum pentoxide coating on titanium for concurrent biocorrosion resistance and enhanced biocompatibility.

BACKGROUND/PURPOSE: Titanium (Ti) dental implants must resist biocorrosion while maintaining biocompatibility. This study developed a dual-layer biphasic calcium phosphates/tantalum pentoxide (BCPs/Ta2O5) coating on Ti to improve both biocorrosion resistance and biological performance. MATERIALS AND METHODS: A dense Ta2O5 inner layer was fabricated via a hydrolysis -condensation process to act as a corrosion barrier. Subsequently, a porous BCPs outer layer was deposited by electrochemical cathodic deposition to provide a bioactive interface. Surface morphology, functional groups, crystalline structure, wettability, surface free energy, coating thickness and nanostructure, protein adsorption, and in vitro bioactivity were characterized. Biocorrosion behavior was evaluated using polarization curve measurements in simulated blood plasma and artificial saliva with and without fluoride ions. Cellular responses, adhesion, proliferation, and differentiation of human bone marrow mesenchymal stem cells, were assessed. Statistical analysis was performed using one-way ANOVA followed by Tukey's post-hoc test. RESULTS: The Ta2O5 inner layer significantly improved biocorrosion resistance, evidenced by increased corrosion potential and reduced anodic current density, even under fluoride-containing conditions. The porous BCPs outer layer increased wettability, surface free energy, protein adsorption, and in vitro bioactivity, thereby promoting cell spreading, cytoskeletal organization, and proliferation. The bioactive BCPs coating on Ta2O5/Ti surface significantly enhanced alkaline phosphatase activity, suggesting a favorable early osteogenic response, without compromising the corrosion protection provided by the underlying Ta2O5 layer. CONCLUSION: Dual-layer BCPs/Ta2O5 coating on Ti surface combines enhanced biocorrosion resistance with osteogenic bioactivity and represents a promising surface modification strategy for Ti dental implants, although studies are required to assess long-term stability and durability.