"comparative evaluation of the initial corrosion of four brands of high copper dental amalgams "

statement of problem: many attempts have been made in order to evaluate the amalgam corrosion behavior as an indicator of biocompatibility. purpose: the aim of this study was to evaluate and compare the initial corrosion of four different brands of dental amalgams. materials and methods: four different types of commercial high copper dental amalgam were studied. a special mold was used and twenty-one samples of each type of commercial dental amalgams were prepared. x-ray diffraction technique was used to investigate the microstructure of freshly prepared specimens. electrochemical potentiodynamic tests were performed in physiological solutions in order to determine and compare the corrosion behavior of freshly prepared sample of four brands of dental amalgams. the physiological solutions were the ringer’s solution and physiological normal saline. five replicate tests on each group of specimens were performed. tafel extrapolation and linear polarization methods determined corrosion potentials and corrosion current densities. the mean value and standard deviations of the results were calculated. the mean values were statistically compared by anova and duncan methods at 95% level of confidence. results: gamma-2 phase was present in freshly prepared sample of each type of commercial amalgam. the results showed statistically significant differences between the mean corrosion current density values of freshly prepared sample of four brands of amalgams (p<0.05). the freshly prepared specimen of sybraloy dental amalgam possesses the higher initial corrosion resistance than the other three, and cinaalloy dental amalgam possesses the lowest corrosion resistance. this trend is independent to the type of physiological environment. conclusion: initial corrosion resistance of each type of commercial dental amalgam is much less than its corrosion resistance that could be obtained after one week. from the viewpoint of the corrosion behavior as an indication of biocompatibilty and for prediction of biocompatibily of the amalgam restoration, it is necessary to pay attention to the initial corrosion of dental amalgam.