In vivo histological evaluation of bioactive NiTi alloy after two years implantation

This work is aimed at evaluating the in vivo histological performance of HA coated NiTi through chemical treatments and the untreated NiTi after two years implantation by animal model. A complete implant–bone interfacial osseointegration was observed after HA coated and untreated NiTi was implanted into the animal model for two years. However, the osseous lamella structure on HA coated NiTi was more mature and the osseous tissue was more compact as compared with that of untreated NiTi, which was ascribed to the differences resulted from nickel ion release from the alloy, cell adhesion ability and osteogenesis mechanism during the early stage of implantation. The bioactivity and biocompatibility of NiTi alloy are significantly improved by coating the alloy with HA through chemical treatment, though the untreated NiTi shows good biocompatibility after long time implantation.