Biocompatibility of titanium implants modified by microarc oxidation and hydroxyapatite coating

A thin hydroxyapatite (HA) layer was coated on a microarc oxidized titanium (MAO-Ti) substrate by means of the sol-gel method. The microarc oxidation (anodizing) enhanced the biocompatibility of the Ti, and the bioactivity was improved further by the sol-gel HA coating on the anodized Ti. The HA sol was aged fully to obtain a stable and phase-pure HA, and the sol concentration was varied to alter the coating thickness. Through the sol-gel HA coating, the Ca and P concentrations in the coating layer increased significantly. However, the porous morphology and roughness of the MAO-Ti was altered very little by the sol-gel treatment. The proliferation and alkaline phosphatase (ALP) activity of the osteoblast-like cells on the MAO/HA sol-gel-treated Ti were significantly higher than those on the MAO-Ti without the HA sol-gel treatment. (c) 2005 Wiley Periodicals, Inc.