Alkali-heat-treated titania coatings on zirconia implants improves bioactivity and osseointegration

Zirconia implants are increasingly used in dental applications due to their favorable esthetics, excellent mechanical properties, and good biocompatibility. Nevertheless, the bioinert nature of zirconia limits early osteogenic response and osseointegration, potentially compromising long-term stability. In this study, a uniform titania (TiO₂) coating was constructed on zirconia surfaces and subsequently subjected to alkali-heat treatment to further enhance surface bioactivity. The modified samples were systematically characterized in terms of surface morphology and chemistry, roughness and wettability, as well as mechanical performance. MC3T3-E1 cells were cultured on the modified zirconia surfaces to evaluate cytocompatibility and osteogenic differentiation in vitro. In addition, a rat femur implantation model was used to assess in vivo osseointegration. The alkali-heat-treated TiO₂ coating modified zirconia exhibited increased surface roughness and improved hydrophilicity without detrimental effects on the mechanical strength of the zirconia substrate. In vitro, the alkali-heat-treated surface promoted cell spreading, proliferation, and osteogenic differentiation. In vivo evaluation demonstrated increased peri-implant new bone formation around the alkali-heat-treated TiO₂ coating modified implants. Overall, combining a uniform TiO₂ coating with alkali-heat treatment provides an effective strategy to improve the osteogenic performance of zirconia implants.