BackgroundTi-Zr alloys have gain more attention as a new metallic biomaterial. using as implants both for orthopedics and dentistry. More recently, our group found promising results for Ti-45Zr alloy, while presenting a low elastic modulusand, a pronounced excellent mechanic character and excellent cell compatibility in vitro. However, the biocompatibility and the potential to promote osteogenesis remains unclear.Methods In this study, the biocompatibility, osteointegration ability, and immune response effects of Ti-45Zr alloy were systematicly investigated in vivo. The biocompatibility of Ti-45Zr alloy was evaluated by hemolysis test and in vivo implantation test in New Zealand white rabbits. The bone integration ability of Ti-45Zr alloy with tissue interface was also investigated by hard tissue section staining and biomechanical experiments. At the same time, the effects of Ti-45Zr alloy on the immune response of Sprague Dawley rats were studied through serum biochemical detection and immunohistochemistry (IHC) staining of hard tissue sections. Interleukin-6 (IL-6) and Interleukin-10 (IL-10) was detected by ELISA. ResultsResults showed that the alloy had good blood compatibility and no body side effects. After implantation in vivo, The serum concentrations of anti-inflammatory and proinflammatory factors reached the highest values at the 9th day, and the inflammation level around the implant hole returned well with the prolongation of the implantation time. On the 14th day, new bone formation was observed around the three materials. The Ti-45Zr alloy was conducive to the polarisation balance of the macrophages.ConclusionThe Ti-45Zr alloy showed exccelent biocompatibility and good osteointegration ability, and it is beneficial to the polarization balance of macrophages.It confirmed that the Ti-45Zr alloy can be used as a dental implant material.