Evaluation on biological safety of Ni-Ti shape memory alloy

To evaluate the biological safety of Ni Ti shape memory alloy it was implanted in experimental animals by two different treatments: In the first experiment Ni Ti shape memory alloy was implanted into the dosal muscle of rats, while in the second experiment Ni Ti shape memory alloy was implanted into the femur and memdiblle of dogs. After 230 and 180 days, rats and dogs were killed respectively and the contents of Ni and Ti in liver, kidney and other tissues were determined by graphite furnace atomic absorption spectrophotometry. The results showed that there was no obvious accumulation of Ti and Ni elements in liver and kidney in experimental animals by the first kind of implantation. However, the Niand Ti contents in liver, kidney and mucosa of nasopharynx in dogs of the implanted group were significant higher than that of the control group （P ＜0.05） in the second experiment. It was suggested that different implanted ways of prosthesis may exert different effect on living body. With regard to the results of the second experiment, a cautious attitude should be taken towards the clinical use of Ni Ti shape mamory alloy. It is necessary to have a further study on surface modification of alloy in order to improve its biological safety.