Biological evaluation of nano-hydroxyapatite-zirconia (HA-ZrO2) composites and strontium-hydroxyapatite (Sr-HA) for load-bearing applications.

The biological response of strontium (Sr) doped hydroxyapatite (HA) and hydroxyapatite-zirconia (HA-ZrO₂) composites produced by employing sol-gel technology, minimal ZrO₂ loadings, and novel microwave-sintering regimes thereby retarding decomposition, is reported. In vitro evaluations indicate that all materials induce a favorable response from rat osteosarcoma cells. In vivo evaluations show osteoconductivity and biocompatibility for both the Sr-HA and HA-ZrO₂. The materials did not cause any inflammatory response in bone. The Sr-HA displays better biocompatibility which may be due to the incorporation of Sr and the formation of a surface apatite layer.