Effect of Topical Acidulated Phosphate Fluoride on Percentage of Streptococcus mutans and Streptococcus sanguis in Plaque

Abstract

The percentage of Streptococcus mutans and Streptococcus sanguis in pooled occlusal plaque and in pooled approximal plaque following 8–10 daily applications of either an acidulated phosphate fluoride (APF) gel or a placebo gel was determined. S. mutans averaged about 9% of the colony forming units (CFU) in the occlusal plaque and 1% of the CFU in the approximal plaque prior to treatment. S. sanguis accounted for about 5% of the approximal isolates and 8% of the occlusal isolates prior to treatment. The APF treatment caused a persistent 45–75% reduction in the percentage of S. mutans in the occlusal samples but did not have an effect on the percentage of S. mutans in the approximal plaque. Great individual variability in the percentages of S. mutans prevented the demonstration of significant differences between the APF and placebo group when parametric statistical tests were employed. When ranking procedures were used, i.e. Kruskal Wallis, Willcoxon tests, the APF was found to have a specific antimicrobial effect against S. mutans in the occlusal plaque, but not in the approximal plaque. This effect was still apparent 12 weeks after the last treatment. There was no effect of the APF on the percentages of S. sanguis in either sample, except at one week after treatment, where the approximal samples showed a significant increase. The plaque and gingivitis scores in the APF group were significantly less than in the placebo group.