抄録
The purpose of this study was to investigate the effect of dentifrices containing low concentrations of fluoride on hydroxyapatite powder and human enamel powder.
Fluoride solutions were prepared containing 100ppm F- in (1) NaF, (2) NaF+20% glycerine (NaF+G), and (3) K-100, and 1, 000ppm F- in (4) MFP, (5) SnF2, and (6) SnF2+50% glycerine (SnF2+G). Some powder was treated with distilled water as the control.
Before treatment, the pH and free fluoride concentration in each solution were measured. Powders were treated with these solutions for 6 min. In all groups, a part of the sample was washed with 1M KOH solution for 24hr, in order to remove CaF2 in the powder and to measure the permanently bound fluoride concentration.
Fluoride uptake was measured, and an acid resistance test and IR analysis were performed.
The pH of SnF2 solution and SnF2+G solution was 2.6, and the other solutions were slightly acidic.
Free fluoride concentration was 7% in MFP solution and 90% in other fluoride solutions.
The fluoride concentration in powder was increased by the application of fluoride solution. NaF, NaF+G, and K-100 caused fluoride uptake similar to that of the MFP group. After washing with 1 M KOH solution, fluoride concentration was decreased in all groups in hydroxyapatite powder, but in NaF, NaF+G, and K-100 groups, fluoride remained above 90%.
The acid resistance test proved that calcium release was inhibited in fluoride groups both after treatment and after washing with 1 M KOH solution. After treatment, acid resistance was more than doubled in SnF2 and SnF2+G groups as compared to the other fluoride groups, but the other groups were similar to each other. After washing with 1 M KOH solution, all fluoride groups had the same acid resistance.
IR analysis showed no clear difference in all the experimental groups.
These findings showed that the effect of NaF solution (100ppmF) was similar to that of MFP solution (1, 000ppmF) on the fluoride uptake and acquisition of acid resistance, and that NaF solution (100 ppmF) for dentifrice use was a useful agent for caries prevention.
