Methods: 34 dental students (ages 23-33) were recruited for the study. All subjects were scored for salivary SM level at baseline using Dentocult® SM test kit. Only subjects with a baseline SM score of 1 or greater were included in the study. Subjects were then stratified by baseline SM level and randomized into 2 groups of 17 each. The experimental group drank bottled water containing 2 gm xylitol per 16.9 fl oz while the control group drank bottled water without xylitol. Participants were asked to drink 3 bottles of water per day. SM test scores were obtained after 2 and 4 weeks. Wilcoxon signed-rank test was used for within-group comparisons of SM over time while Mann-Whitney U test was used for between-group comparisons of SM.
Results: 32 participants, 16 control and 16 experimental, completed the study. Using the Wilcoxon signed-rank test, both groups demonstrated a significant reduction in SM from baseline to 2 weeks (p=0.014 for control group, p=0.004 for experimental group) and from baseline to 4 weeks (p=0.017 for control group, p=0.035 for experimental group). The Mann-Whitney U test showed no significant difference in SM reduction between groups from baseline to 2 weeks (p=0.660) or from baseline to 4 weeks (p=0.345).
Conclusion: Drinking 3 bottles of water a day lowered S. mutans levels after 2 and 4 weeks. The addition of xylitol to bottled water had no effect on S. mutans levels. Drinking three 16.9 fl oz bottles of water per day was effective in lowering S. mutans scores and should be recommended to patients as a simple way to lower caries risk.