| Ti-25Nb-10Ta-1Zr-0.2Fe(TNTZ) alloy is a new type of titanium alloy developed by DQ-Y study group from school of Materials Science and Engineering, Central South University, it has been applied for patents. Its elastic modulus ratio is closer to the human skele than other alloys already applicated in clinical and it doesn’t contain harmful metal elements, so it may have wide application in clinical prospects. At present, studies of TNTZ are focused on the material professions, such as wear resistance, fatigue resistance, hardness and elastic characteristics. There is rarely a comprehensive study on its biological security.Objective:In this study, we combine in vitro experiments and animal experiments, to test the biocompatibility of TNTZ from three levels:cells, blood and the tissue, to provide a reference for its clinical application.Methods:^According to the national standards GB/T16886.4-2003/ISO10993-4:2002Biological evaluation of medical devices Part IV:Selection of tests for interactions with blood. Study the rate of hemolysis of the experimental metal through in vitro direct contact method, put5g alloy into the diluted rabbit blood samples keep constant temperature for1hour, using a spectrophotometer to test the hemolysisrate.2. According to the nationalstandardsGB/T16886.5-2003/ISO10993-5:1999Biological evaluation of medical devices Part V:in vitro cytotoxicity. Study metal toxicity levels via cultivating L929cells by alloys’extracting liquid, using these methods:observing cell morphology under a microscope, determining cell proliferation by MTT assay and flow cytometry methods.3.According to the national standards GB/16886.6-1997/ISO10993 -6:1994Biological evaluation of medical devices Part VI:Tests for local effects after implantation. Determine the in vivo toxicity of the experimental metal by rabbits experiments after4,12,26weeks.4. Using X-ray to observe the impact of alloy on bone.5. Using decalcified slices and undecalcified hard tissue sections to observe the alloy’s impact on the surrounding bone, observing whether it cause inflammatory, necrosis and tumor responses.Results:1. The hemolysis rate of TNTZ is2.3%, lower than the national standard (5%).2. TNTZ does not affect the morphology and proliferation of L929cells, the morphology and number of each group were similar, cells were fusiform or polygonal, with extended pseudopodia. TNTZ’s index of MTT was1.031+0.059, ratio of S stage was40.32+5.49, there were not statistically different (P<0.05) comparing with other alloy groups. Its cytotoxicity is grade0.3. TNTZ did not cause any inflammation, tumor, did not affect wound healing after implanted in rabbits femur. Implant-bone interface were contacted tightly, had no osteolysis phenomenon, so it had no toxic effects in experimental animals.Conclusions:1.TNTZ is an alloy of no hemolysis, no cell toxicity, no adverse effects in experimental animals, so it is in line with countries standards.2.TNTZ alloy just have a simple contact with the bone, not combination. There should be continuous study on the surface treatment and activation before biological applications. |
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