Hydroxyapatite coating on zirconia using glass coating technique

The aim of this study was to develop a novel hydroxyapatite (HA) coating method on zirconia using glass coating technique. A borosilicate glass, the mixture of the glass and HA (30, 50, 70, and 90 mass%), and the 100% HA were coated on two kinds of zirconia discs and fired at 900-950°C. After the final coating, the surface of the sample was etched for 3 min in an acid-mixture of 3% HF and 5%HNO3 to remove the surface layer covered with glass and to obtain the biocompatible surface layer with HA. The shear bonding strength of the glass to zirconia fired at 950 and 1050°C were determined. There were no significant difference in the bonding strengths between the kind of zirconia (p>0.05). Whereas, the bonding strengths fired at 1050°C were significantly higher than those at 950°C (p<0.05). These results suggest that the HA containing glass-coated zirconia, namely functionally gradient structure, could be systematically produced using the glass coating technique and the acid etching.