Impact of fluoride, milk and water rinsing on surface rehardening of acid softened enamel. An in situ study

Abstract

Baseline Knoop Hardness (mean +/- S.D.) amounted to 403.1 +/- 39.4. Immediately after softening, mean SMH was reduced to 214.4 +/- 24.1 KHN. Rinsing with 250 ppm fluoride, milk or water after 5 minutes or 30 minutes intraoral exposure of softened samples had a significant effect on rehardening. The increase of SMH (DeltaKHN) was highest after rinsing with fluoride (5 minutes: 95.0 +/- 18.3; 30 minutes: 94.2 +/- 24.3) followed by milk (5 minutes: 77.1 +/- 14.1; 30 minutes: 80.3 +/- 18.7) and water (5 minutes: 49.0 +/- 9.9; 30 minutes: 47.0 +/- 14.1), but did not achieve baseline values. It is concluded that a single rinse with a 250 ppm SnF2/Olaflur solution, milk or water increases rehardening of previously acid softened enamel.