Abstract: Objective To study and analyze the quantity of the Ni-ion and Cr-ion educed from two types of Ni-Cr-porcelain alloy crowns in artificial saliva, to instruct clinical applications. Methods Ni-Cr porcelain alloy which contains Cr 26.0% and 12.6% were fritted into 24 Ni-Cr porcelain fused to metal crowns, and divided two groups according to Cr concentration. Both two groups included 12 ones respectively. Twenty-four samples were averagely divided into two groups. Group A: High-chromium alloy group; Group B: Low-ch romium alloy group.
They were put into artificial saliva in sealed container. The concentration of Ni-ion and Cr-ion were measured at the first, second, fourth, eighth, sixteenth and thirty-second weekends with graphite furnace atomic absorption spec trometry. Results 1）The educed Cr-ion from 24 samples of two groups increased slowly at the first weekend to the four week, then decreased. The educed Ni-ion from 24 samples kept increasing from first weekend to the thirty-second weekend. 2）The mass of low-chromium porcelain alloy group decreased were more than that of highchromium alloy group after experiment（P<0.01）. Conclusion 1）The educed chromium ion level reached the peak at the forth weekend. 2）The educed nickel ion in the low-chromium alloy group was much higher than that of the high-chromium alloy group. 3）The loss of mass in low-chromium alloy group was much higher than in the highchromium alloy group.