Enhanced osteogenic activity of titania-modified zirconia implant by ultraviolet irradiation.

Zirconia is a superior implant material owing to its high mechanical strength, durable corrosion resistance, superior aesthetic effect and excellent biocompatibility. However, the bioactivity of zirconia surfaces remains a great challenge for implant osseointegration. A titania (TiO) coating was innovatively synthesized on the surface of zirconia by infiltration in a suspension of zirconium oxychloride and titania for dense sintering. Subsequently, the coating was subjected to ultraviolet (UV) light to enhance the biological inertness of zirconia. Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and contact angle analysis were conducted to confirm the surface characteristics. Afterwards, assessments of cell adhesion, proliferation and osteogenic differentiation of MC3T3-E1 cells were performed. Zirconia samples were implanted into rat femurs to assess biocompatibility and host tissue response . Micro-CT evaluation and histological testing were conducted. After UV irradiation, the content of hydroxyl groups and hydrophilicity of TiO-modified zirconia were significantly increased. The results of experiments showed that TiO-modified zirconia subjected to UV light could promote cell proliferation and spreading, enhance ALP activity and the degree of mineralization, and upregulate osteogenesis-related genes. Furthermore, assessments confirmed that UV-irradiated TiO-modified zirconia implants maximized the promotion of osseointegration. TiO-modified zirconia after UV treatment will have broad clinical application prospects in improving the osseointegration of zirconia implants.