Study On The Changes Of Corrosion Resistance Properties Of Nichel-Chromium Alloys Modified With Proteins

Purpose: The objective of this study was to evaluate the corrosion properties and the resistance to microbiologically influenced corrosion of Nichel-Chromium alloys which were pretreated with different proteins,which would provide experimental data to enhance the dental alloys' corrosion resistance property.Methods: 1.The NiCr alloy specimens were pretreated with artificial saliva contained bovine serum albumin(BSA) or lysozyme(LSZ) of different concentration and then investigated with potentiodynamic polarization measurement to observe the changes of corrosion peopertise. 2.The Ni Cr alloy specimens were exposed to artificial saliva with 1% bovine serum albumin or 0.22% lysozyme for 24 h.Then these alloys were cultured in the solution of streptococcus mutans for different times and investigated with electrochemical measurements to study the effects of proteins and time on the resistance to microbiologically influenced corrosion of the NiCr alloys.Results: 1.The Rp and Ebr of the specimens which were modified with proteins increased obviously than those untreated and developed more when the proeins' concentration was higher. 2. The elestrochemical results indicated that the corrosion resistance of all specimens decreased with time which NiCr alloys were cultured in the solution of streptococcus mutans for.And the ANOVA analysis indicates that both BSA group and LSZ group were higher than the control group(P<0.05) and LSZ group was superior to BSA group cultured in the solution of streptococcus mutans for 12 h. When cultured for 24 h, the corrosion resistance of BSA group and LSZ group had no significantly difference(P>0.05), but was still higher than the control group. After 36 h culture time, the control group and the BSA group had no statistical difference in corrosion resistance(P>0.05), while the LSZ group had the poorest corrosion resistance. And when the culture time extended to 48 h, the control group had a better corrosion resistance compared with the BAS group and the LSZ group(P<0.05), but BSA group was showed lower corrosion properties than LSZ group. The potentiodynamic polarization curve and electrochemical impedance spectroscopy obtained consistent results.Conclusion: The corrosion resistance properties of Ni-Cr alloys were increased after modified with bovine serum albumin and lysozyme and this effect was positively correlated with the concentration of proteins.Otherwise,when these pretreated alloys were cultrued into solutions of streptococcus mutans,the BSA and LSZ on the surface could effectively inhibit the microbiologically influenced corrosion for just the early time.With the continuing role of streptococcus mutans and the consumption of the absorbed proteins, the corrosion resistance of Ni Cr alloys toward streptococcus mutans would become lower than the alloys without absorb protein.