Protective Effects Of Ni-Ti Instruments By Ion Nitriding

To investigate the protective effects of titanium nitride(TiN) coating on improving the corrosion resistance and inhibiting ion dissolution of Nitinol(Ni-Ti) instruments by ion nitriding. A total of 30 samples of Ni-Ti alloy were randomly assigned into 2 groups of 15 samples each.Group A: samples were coated with TiN by ion nitriding heat treatment process.Group B: samples were not coated.The surface hardness and corrosion resistance of the two groups were measured by nano-indentation and electrochemical test.A total of 60 endodontic instruments were randomly assigned into 2 groups of 30 samples each.Group C: samples were coated by the same method as Group A and prepared for extracts.Group D: samples were not coated but prepared for extracts.The dissolution of Nickel ion in 2 groups extacted after 1 and 10 days was detected. The surface hardness of Group A was similar to Group B. The polarization curve of Group A moves in the direction of positive potential and the self-corrosion potential of Group A was higher than that of Group B.After 1 and 10 days of extraction,The dissolution of Nickel ion of Group C was significantly lower than that of Group D(P<0.05). The protective TiN coating using ion nitriding can improve the corrosion resistance of Ni-Ti alloy.It has a significant inhibitory effect on the dissolution of Nickel ion,and does not affect the hardness of Ni-Ti alloy.