Hard-tissue-engineered zirconia porous scaffolds with hydroxyapatite sol-gel and slurry coatings

A zirconia (ZrO(2)) porous scaffold was coated with a gradient apatite layer to induce osteoconductivity with the use of a combination of sol-gel and powder slurry methods. The ZrO(2) was used to impart mechanical strength and the apatite layer was coated for functional biocompatibility. The coating layer, from the outside in, was composed of sol-gel hydroxyapatite (HA)/slurry HA/slurry FA. The sol-gel coating powder had a lower crystallinity than the slurry coating powder. The sol-gel HA coating over the HA/FA slurry coating layer made the surface very smooth. The sol-gel coating over the slurry coating layer enhanced the bonding strength up to 33 MPa. The dissolution rate of the sol-gel/slurry coating layer was much higher than that of the slurry coating. Moreover, the rate could be controlled by altering the heat-treatment temperature of the sol-gel HA layer. The MG63 cells cultured on these materials grew and spread in a different manner, depending on the coating layer. However, the proliferation rates of the cells on both coating systems were not much different.