| Background The mature enamel is composed of organisnu inorganic substance and water. The main inorganic component of the enamel consists of a mineral called hydroxyapatite, Ca10(PO4)6(OH)2, the ion of which may bring out permutation. For example, the hydroxy can be replaced by fluorine ion. When the incremental lines reach the enamel surface, it forms the perikymata, where the hydroxyapatite crystal's array is not regular. The number of the pores increase because of the irregular crystal's array. We can also find the irregular Tomes processes pits, enamel caps, focal holes and the micropores whose diameter is 10-15nm under scanning electron microscope. Some scholars think that the enamel has the selective permutation due to it's muti-pores. The pores in the enamel have protein and water. The presence of the organic substance may adjust the diffusion process of the enamel and the reaction between the minerals and the environmental factors in the oral cavity. Recent research reveal that the surface of enamel would be covered a biomembrane named dental plaque if only any part of the enamel entered the oral cavity. A series of the metabolism activities will proceed in the dental plaque. Follow the pH change between the enamel surface and the biomenbrane interface, the process of the demineralization and the remineralization will happen.The development of the enamel caries is a continuous process from the lose of thecalcium and the phosphate to demineralization under the white lesions, and the formation of the dental cavity lastly. The earliest manifestation of the caries is crystal resolution of the extreme exterior enamel, which makes the space in the crystals increase. With the entrance of a great quantity acid, the number of micropores raise which results in the diffusion of calcium and phosphate into the enamel few hundred micrometers. Besides the changes of the surface layer, 20-50nm of the extreme exterior enamel may maintain relative high mineralization after the initial resolution. Resolution and the redeposition may occur simultaneously within a certain range of the pH. Some researches point out that a certain restore kinetics mechanism called remineralization performs a very important function otherwise a high incidence of the dental caries may present. The functions of the fluoride are as follows: (1)affect the mineral's character, amount and the deposition situation of the artificial dental caries, (2)converse the minerals of the caries to fluoroapatite, decrease the susceptibility to the acid resolution. (3) yield relative big crystals on the dental caries's surface ,also decrease their susceptibility to the acid erosion. (4) improve the hydroxyapatite's structure, promote the decalcificated mineral's remineralization. (5) inhibit the enzyme and the growth of the bacterium which result in dental caries in the dental plaque, (6)relieve the adsorption of the protein and the bacterium, reduce the surface free energy.Frant and Ross suggested the fluorine ion selective electrode assay in 1966, whose advantage is quickness, convenience and relative extensive measure range. The method has high tolerance to ectogenic ions (for example sulfur and phosphorus) and inorganiccompound, whereas these ions and materials often interfere the measurement of the chromatometry. The sensitivity of the fluorine ion selective electrode assay is 1 g concentration. The minimum concentration of the measurement may up to 2.5 g concentration with the development of the microelectrode.Objective To investigate the fluorine ion release, the anticariogenic effect and the bond strength of a new type slow fluoride orthodontic bonding adhesive in vitro, and to discuss the fluorine ion release and anticariogenic mechanism, the relationship between the concentration and the amount of fluorine ion release, the relationship between the concentration and the anticariogenic effect of the new type slow fluoride orthodontic bonding adhesive.Methods Use the fluorine sensitive electrode and the reference electrode to m...
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