Two kinds of APF with different properties [Liquid type APF(L-APF group)·Gel type APF(GAPF group)] were treated to examine the effect of APF on enamel with changes in the microstructure of the enamel surface, the atomic analysis of the cross section of the enamel, measurement of the amount of extraction of the fluoride of alkaline solubility and changes in the acid resistance ability of enamel by using bovine enamel.
1. The spheroidal structures were obtained in both the L- and G- APF groups. The size in the G-APF group was slightly larger than in the L-APF group.
2. EPMA analysis showed larger amount of fluoride uptake and infiltration in the L-APF group than in the G-APF group after APF treatment of the enamel.
3. The amount of the L-APF group alkaline solubility fluorine was significantly greater than that of the G-APF group.
4. As a result of an acid resistance examination, the acid resistance in the L-APF group was treated with APF found to be significantly higher than that of the control group (no APF treated group).
From the above-mentioned results, it was suggested that L-APF was more effective in caries prevention than G-APF.