Enhancing the bioactivity of zirconia and zirconia composites by surface modification

Among bioceramics, zirconia (ZrO2) and alumina (Al2O3) possess exceptional mechanical properties suitable for load-bearing and wear-resistant applications but the poor bioactivity of these materials is the major concern when bonding and integration to the living bone are desired. This article investigates two different approaches and their underlying mechanisms to improve the bioactivity of zirconia (3Y-TZP) and a zirconia composite with alumina (10Ce-TZP/Al2O3). Chemical treatment approach applied on 3Y-TZP where the substrates were soaked in 5M H3PO4 to create chemically functional groups on the surface for inducing apatite nucleation. X-ray photoelectron spectroscopy (XPS) was used to detect chemical changes and X-ray diffraction (XRD) to monitor phase changes on the surface before and after acid treatment. Alternate soaking approach applied on 10Ce-TZP/Al2O3 consisted of soaking the composite substrates in CaCl2 and Na2HPO4 solutions alternately to make a precursor for apatite formation. The bioactivity was evaluated by apatite-forming ability of surface-treated materials in simulated body fluid (SBF). Both methods resulted in the formation of hydroxyapatite on the surface of materials; however, alternate soaking approach showed to be a simpler, faster, and more effective method than the chemical treatment approach for enhancing the bioactivity of zirconia materials. (c) 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2012.