STUDIES ON THE PREVENTION OF DENTAL CARIES WITH STANNOUS FLUORIDE

III. Effect of stannous fluoride on the acid solubility of powdered enamel (2nd report)

Abstract

The procedure for determining the solubility of powdered enamel was as follows: Using the mechanical shaker, 100 mg of 100-150 mesh enamel powder was treated with 10 ml of 2% NaF or 1, 2, 4, 8 and 16% SnF₂ solution for 5 minutes at 20°C respectively, and in addition, the samples treated similarly four times in repetition were also prepared. Control groups were treated with distilled water in place of fluorides. The sample was decalcified with 10 ml of N/5 acetate buffer (pH 4.0) for 20 minutes at 37°C. The decalcification was repeated ten times, and in each run, amount of calcium and phosphorus dissolved from samples were determined with EDTA-titration method and Phospho-Vanado-Molybdate method respectively.
The effectiveness of these fluorides on reducing the acid solubility of powdered enamel was estimated by the sum of calcium and phosphorus values in each decalcification run together with the cumulative value of them.
Following conclusion were obtained.
1. The lower acid solubility was found in groups treated with fluorides than in control groups.
2. In earlier decalcifing stage, the effects of reducing acid solubility were indicated superior in samples treated with 1% or 2% SnF₂ solution to that treated with 2% NaF, 8% or 16% SnF₂ solution.
3. Four times repeated treatment with either NaF or SnF₂ were more effective than single treatment in reducing the solubility. Among SnF₂groups, the differences of total dissolved calcium and phosphorus amount between single and four times treated samples were more marked in 1% or 2% groups than in 8% or 16% groups.