Antimicrobial effect of fluoride mouthrinse on mutans streptococci and lactobacilli in saliva.

PURPOSE This study was designed to determine whether the long-term use of fluoride mouthrinse affects the salivary levels of mutans streptococci and lactobacilli. METHODS The subjects consisted of 414 school children aged 7, 10, and 12 yrs. Among these subjects, 243 children had received fluoride mouthrinse since 5 years of age at nursery schools, and comprised the "mouthrinse group." The remaining 171 children, the "no mouthrinse group," had not received fluoride mouthrinse. All of the children received routine dental health education. The levels of mutans streptococci and lactobacilli for the subjects in both groups were measured using Dentocult SM Strip mutans and Dentocult LB Dip Slide, respectively. Dental examinations were conducted to obtain data on caries prevalence (dfs and DMFS). Logistic regression analysis was used to control confounding factors: age, dfs, DMFS, frequency of toothbrushing, sum of permanent tooth surfaces sealed, frequency of sweet snacks, frequency of sweet drinks, and the use of fluoridated toothpaste. RESULTS There was a significant difference in mean DMFS between the mouthrinse group and no mouthrinse group at all ages. Children with fluoride mouthrinse had lower levels of mutans streptococci, and there was a significant association between the experience of fluoride mouthrinse and the score of Dentocult SM strip Odds ratio: 0.64, P < 0.05. However, there was no significant relation between the experience of fluoride mouthrinse and the score of Dentocult LB Dip Slide. The results of this study demonstrated that the long-term use of fluoride mouthrinse affected the detectable levels of mutans streptococci, but did not affect the levels of lactobacilli. CONCLUSIONS These results suggest that fluoride mouthrinse might contribute to reducing the number of mutans streptococci.