The purpose of this investigation was to study the low level fluoride on the resolutive behavior of dental enamel in vitro.Twelve enamel slabs were used to treat with acidulated phosphate fluoride solutions containing different F concentration and then with acidic artificial carious gel.Chemical analysis were carried out with atomic absorption spectrophotometer,fluoride ion-selective electrode and electron microprobe.Results indicate that different F concentration in environmental solutions make different physicochemical ways on effects to enamel demineralization,they are specific and non-specific absorption of fluoride ions or dissolution and reprecipitation of fluoridated apatite and CaF(2).