The characteristic and osteogenic effect of a nanoporous coating of zirconia implant

Zirconia ceramics have become increasingly used as dental implant material which is mainly due to their “tooth-like” color, superior biocompatibility, and excellent mechanical properties. However, the bio-inertness of the zirconia surface limits its use for a wider range of clinical applications. To enhance the surface bioactivity, a combination of magnetron sputtering, and anodization has in the present study been used to deposit a homogeneous nano-porous coating (ZrNP) on the zirconia surface (forming ZrO₂/ZrNP with a ZrNP pore diameter of 20–30 nm, and a ZrNP layer thickness of ～2 μm). EDS and XRD analysis showed that the distribution of the surface chemical components, as well as the crystalline structure of the zirconia (ZrO₂), remained unchanged. On the other hand, the hydrophilicity of the ZrO₂/ZrNP surface became significantly improved (as compared with a control group). In addition, the bond strength of the coating was decreased as a result of the anodization treatment. Moreover, both the Zr and ZrNP nanolayers exhibited improved proliferation and osteogenic properties in the in vitro cell experiment. Also, the ZrNP nanolayer was found to promote the biocompatibility and osteogenic ability to the largest extent. The ZrNP nanolayer did also provide numerous adhesion sites for MC3T3-E1 whereby the cell morphology could be enhanced. Additionally, the nano porous ZrNP layer improved the new bone formation around the zirconia implant and did robustly enhance the push out bond strength, thereby indicating the best osteointegration ability. In conclusion, a nano porous zirconium layer has been found to be very promising for the improvement of the bioactivity of the zirconia implant material.