| Objective:In this experiment, titanium nitride film on the surface of dental medical nickel-base alloy(nickle-chromium and nickle-titanium alloy)was deposited with filtered arc plating technology. Modern physical, chemical as well as cell biology research methods were used to comprehensively evaluate surface structure, physicochemical property, antibacterial property and biological property of nickel-base alloy after modification. The aim was to further promote safer and wider application of modified nickel-base alloy in the clinical area of oral medicine and to provide the basis for experimental research and theoretical foundation.Methods:1,A layer of titanium nitride film was deposited uniformly on the surface of dental medical nickel-base alloy using filtered arc plating technology.2,The surface morphology, crystal structure, phase composition, micro-hardness, bond strength of film-substrate interface, carrying capacity as well as thickness of TiN film was measured by SEM,XRD,microhardness tester and electronic universal testing machine, respectively.3,Atomic absorption spectrometer was used to examine the effect of surface nitriding on the releasing content of Ni ions from nickel-base alloy socked in artificial saliva with different conditions.4,Nickel-base alloy before and after nitridation was soaked in Candida albians, Streptococcus mutans fluid, respectively. After incubation for a certain time, the amount of bacterial adhered on the surface of material was compared by electron microscope and colony-forming unit counting method.5,The primary human gingival fibroblasts were cultured with improved tissue explants method. Morphological and immunocytochemical methods were used to identify cell origin and to evaluate the efficiency of primary culture.6,The effect of surface nitriding on proliferation rate, cell cycle and apoptosis of human gingival fibroblast was evaluated comprehensively by MTT assay and flow cytometry(FCM).Results: 1,After surface nitriding, the structure of TiN film on the surface of material was quite compact, without defect such as bubble and crack, although there are some pores in some areas. Modifying substance mainly existed in the form of TiN. The micro-hardness of TiN film was 758Hv0.05kg and 718Hv0.1kg, respectively. The value of bond strength was 38.6N. The thickness of TiN film was 0.267μm. Under the pressure of 6GPa, there was no crack on the TiN film.2,Releasing contents of Ni ions from modified group were all significantly lower than that from unmodified group in different PH values of artificial saliva at different time(P<0.05). In the same group, the release of Ni ions in artificial saliva with acidic PH value was increased compared with neutral PH value (P<0.05).3,After incubation for 24h,48h,72h in Streptococcus mutans fluid, the amount of viable organism on the surface of modified Ni-Cr alloy group was significantly lower compared with unmodified group(P<0.05). Likewise, the amount of viable organism on the surface of modified Ni-Ti alloy group was lower than that of unmodified group after incubation for 24h,48h,72h in Candida albians fluid. The difference was statistically significant(P<0.05).4,Improved covering coverslip successfully cultured primary human gingival fibroblsts and significantly improved the success rate of training.5,Compared with unmodified group, cell proliferation rate in modified alloy group was significantly greater(P<0.05).6,After surface nitriding, the FCM demonsted that the percentage of G0/G1 phase and G2/M phase cells reduced, respectively. The S phase cells and PrI significantly increased(P<0.05).7,The apoptosis rate reduced after surface nitriding of nickel-base alloy(P＜0.05).Conclusions:TiN film deposited on the surface of dental medical nickel-base alloy with filtered arc plating technology has satisfactory mechanical property, corrosion resistance as well as surface stability. Nickel-base alloy after modification displays the ability of suppressing bacterial adhesion and ideal biological property.
|
PDF Full Text Request