R. Y. Chan, K. Yeung, W. W. Lu, A. H. W. Ngan, K. D. Luk, K. M. Cheung, The University of Hong Kong, Hong Kong, Hong Kong; S. L. Wu, P. K. Chu, City University of Hong Kong, Hong Kong, China; X. Liu, J. C. Y. Chung, City University of Hong Kong, Hong Kong, Hong Kong
Nickel-titanium (NiTi) shape memory alloy has attracted numbers of medical applications such as scoliosis correction and cardiovascular reconstruction surgery. However, in addition to its high nickel concentration that raises a concern on the safety issue for long-term surgical implantation, this material is not osteo-conductive. Therefore, implant failure is likely happened due to non-coherent interface between bone and implant. To tackle these problems, we make use of oxygen and sodium plasma immersion ion implantation (PIII). Enhancement of corrosion resistance using oxygen PIII has been proved by our previous studies. The present study aims to characterize the in vitro behaviour of the surface modified NiTi materials in terms of osteoblast proliferation and mineralization. In cell culturing osteoblasts were proliferated on the surface for 2, 8 and 14 days. In mineralization testing osteoblasts were cultured for 8 and 14 days supplemented with 50 mg/ml ascorbic acid and
10 mM Na b-glycerophosphate. Samples were then covered with
40mM Alizarin Red solution so as to stain the calcium nodules.
The culture results suggest that the number of osteoblasts on modified NiTi seems to be higher than the untreated. Although this observation is not significant, it still indicates that oxygen and sodium PIII does not adversely affect the osteoblast proliferation in vitro. In mineralization test, the modified surface is slightly better as compared with the untreated. In summary, the oxygen and sodium PIII can enhance the NiTi bioactivity and corrosion resistance at the same time. The in vivo behaviour will be confirmed by animal testing.
Summary: Nickel-titanium (NiTi) shape memory alloy has attracted numbers of medical applications such as scoliosis correction and cardiovascular reconstruction surgery. However, in addition to its high nickel concentration that raises a concern on the safety issue for long-term surgical implantation, this material is not osteo-conductive. Therefore, implant failure is likely happened due to non-coherent interface between bone and implant. To tackle these problems, we make use of oxygen and sodium plasma immersion ion implantation (PIII).
