Objective:To observe and compare the inhibitory effect of two concentrations of fluor protectors on demineralization of human enamel in vitro.Methods:40non-carious human enamels were randomly divided into four groups with 10 samples in each group

of which 5 samples were used for experiment

5 samples were used as spare ones.0.5% fluor protector and 0.1% fluor protector were applied to the experiment groups

while 0.02% sodium fluoride and deionizer water were applied to the control groups.Then the specimens had been dematerialized for 48h

the amounts of phosphorus and calcium dissolved in the acid solution were determined by atomic absorption spectrophotometer and ultraviolet spectrophotometer respectively.Results:The experiment groups were better than the comtrast groups at preventing demineralization

and there was significant difference between experiment groups and contrast groups(P<0.0001);There was no significant difference between 0.5% fluor protector group and 0.1% fluor protector group (P>0.05);but there was significant difference between 0.02% sodium fluoride group and vavuity group (P<0.05).Conclusion:Both two different concentrations of fluor protectors are effective in inhibiting demineralization of human enamel in vitro.There is no significant difference between two groups in their inhibitory effects.