Advancing titanium implant performance: Optimizing hydroxyapatite electrophoretic deposition through comparative analysis of surface pretreatment techniques

Hydroxyapatite (HA) was successfully coated on commercially pure titanium (CP-Ti) using the electrophoretic deposition (EPD) technique to enhance titanium's bioactivity for orthopedic implants. This work investigated the impact of surface pretreatments, including grinding, etching, and anodization, on the HA coating's properties. Each pretreatment modified the CP-Ti's topography and surface roughness, with etching achieving the highest surface roughness (Sa = 1.88 µm). Moreover, SEM analysis verified that etching created a rough surface with a concavity structure, leading to more organized and denser HA deposition. In contrast, anodization and grinding resulted in uneven, porous coatings. All HA-coated samples displayed improved hydrophilicity, implying enhanced bioactivity, with the anodized sample achieving the lowest contact angle (2.2°). Corrosion tests in simulated body fluid (SBF) revealed increased corrosion potential (E_corr) in HA-coated samples, with minimal impact on corrosion current density (i_corr). Furthermore, the anodized sample showed the highest corrosion resistance due to its oxide layer. Post-immersion tests demonstrated flower-like apatite crystal formation on the HA coating. These findings suggest that EPD-applied HA coatings significantly improve the bioactivity of CP-Ti, regardless of the various applied pretreatment techniques. Remarkably, etching pretreatment resulted in superior osteointegration, as evidenced by the homogeneous flower-like apatite with a Ca/P ratio of 1.70, closely resembling the HA phase.