Bonelike apatite formation induced on zirconia gel in a simulated body fluid and its modified solutions

Formation of bonelike apatite on zirconia gel in a simulated body fluid (SB F) with ion concentrations almost equal to those in human blood plasma, in modified SBF solutions to have increased pH values, and modified SBF soluti ons to have increased concentrations of calcium and phosphate ions has been investigated. The zirconia gel forms apatite on its surface in SBF, indica ting that Zr-OH groups, abundant on the gel, act as effective apatite nucle ation centers. Apatite formation is accelerated by increases in pH and in t he concentration of calcium and phosphate ions, which is explained by an in crease in the ionic activity product of the apatite in the SBF. These resul ts suggest that zirconia ceramics may exhibit a bone-bonding ability by for ming an apatite layer on their surfaces in the living body when they are mo dified to have many Zr-OH groups on their surfaces.