Abstract: PURPOSE: To evaluate the effect of supplementation containing iron and/or fluoride on eroded enamel in vitro. METHODS: Eighty enamel specimens collected in orthodontic treatments were randomly allocated into 4 groups of 20 samples each: C (control,deionized water); Fe2+ (15 mmol/L FeSO4); F- (1.23% NaF) and Fe2+ + F- (15 mmol/L FeSO4 and 1.23% NaF ). Before all samples submitted to 6 alternating demineralization and remineralization cycles, they were pre-treated with one of the experimental solutions for 1 minute. One complete cycle consisted of the following steps: ①demineralization in 5 mL beverage (Coca-Cola, pH=2.58) for 5 minutes under gentle agitation; ②remineralization in 5 mL artificial saliva for 1 hour at 37℃. The effect of erosion was observed by enamel surface morphology and measured by superficial micro-hardness (SMH). One-way ANOVA was performed using SPSS18.0 software package for analysis of the data. RESULTS: The SMH of enamel after erosion by carbonated drinks was significantly lower than the SMH before erosion. When ferrous sulfate with or without fluoride was tested for the prevention of enamel demineralization, there was statistically significant increase in the SMH of enamel in comparison with the control (P＜0.001). However, the experimental solutions did not differ significantly among them. Scanning election microscope showed the deposition on the enamel surface after iron or fluorine treatment ,and the damage degree of the enamel surface were reduced compared with the control. CONCLUSIONS: Iron and/or fluoride was shown to be effective to enhance the acid resistance of enamel,while the combined use of fluoride and iron in group Fe2++F- had no cumulative effects.

Key words: Ferrous sulfate, Enamel, Erosion, Surface morphology, Surface micro-hardness