The Biocompatibility Of The Porous NiTi Alloy Implant Material

ObjectiveThe different shape and bioactive surface modification methods are applied in every implant system in order to improve bioactivity of implants materials and acquire firmer implants - bone bonding and improve the long - term stability after implantation. As a kind of ideal material for repair and replace of hard tissue of human body, NiTi shape memory alloy has good mechanical property and bio-compatibility. Porous NiTi alloy has thin weight and high specific intensity. 10 - 100μm (cell dimension) porous structure confirms transmission of body fluid of human body and ingrowths of mineral and fiber tissue, then made it firmer combine with around tissue of human body and the commutative pores was favourable for affusion of bioactive HA.The Porous NiTi alloy used in this study was supplied by Eastnorth University ceramic institution. With Ti and Ni powders as main material, it was prepared by powder metallurgy using TiH₂, NH₄HCO₃ as pore —forming material. At the same time, the method of vacuum affuse HA was applied to make the new implant material. The pores consisted of the large pore size of 100 -500μm and the small pore size of 1 - 50 μm as well as the micropore of under 1 μm, which formed a perfect microrough surface and tight - integrated bioactive coat body ingrowths.This study was to investigate the biocompatibility of the porous NiTi alloy and the porous NiTi alloy with affusion of HA.MethodsHemolysis test;was measured to evaluate the blood compatibility of the material. Saline was as negative control and pure lead as positive control. L929 cell line was cultured in different cell culture medium steeps: pure titanium surface as negative control, pure lead as positive control and RPM culture as blank control. MTT assay was used to evaluate the living cell number in the Id, 2d,3d, 4d,5d and 6d. The OD value in different steeps was statistically compared and draw a Cell Growth Curve of L929.Results1. Two experiment groups passed the hemolysis test, and the emolysis rate was 0.67% and 0. 56%. 2. The RGR rate of the cell in steep of porous NiTi was77.06% , 94.79% , 85.71% , 74.90% , 69.5% , 59. 89% in the day 1, 2, 3, 4, 5 , 6 day respectively and 70. 65% , 111. 23% , 95. 65% , 92. 19% , 129. 10% , 132. 08 in the the porous NiTi alloy with affusion of HA. There was no significant difference between the experiment group and negative control, but significant between the experiment group and positive control.ConclusionsThe porous NiTi alloy with affusion of HA shows well biocompatibility in the biological tests and it combines the rough surface and the osteoinductivity of HA . Animal test can be made to prove it.