Linear response of mutans streptococci to increasing frequency of xylitol chewing gum use: a randomized controlled trial [ISRCTN43479664]

Participants (n = 132) were randomized to either active groups (10.32 g xylitol/day) or a placebo control (9.828 g sorbitol and 0.7 g maltitol/day). All groups chewed 12 pieces of gum per day. The control group chewed 4 times/day and active groups chewed xylitol gum at a frequency of 2 times/day, 3 times/day, or 4 times/day. The 12 gum pieces were evenly divided into the frequency assigned to each group. Plaque and unstimulated saliva samples were taken at baseline and five-weeks and were cultured on modified Mitis Salivarius agar for mutans streptococci enumeration.There were no significant differences in mutans streptococci level among the groups at baseline. At five-weeks, mutans streptococci levels in plaque and unstimulated saliva showed a linear reduction with increasing frequency of xylitol chewing gum use at the constant daily dose. Although the difference observed for the group that chewed xylitol 2 times/day was consistent with the linear model, the difference was not significant.There was a linear reduction in mutans streptococci levels in plaque and saliva with increasing frequency of xylitol gum use at a constant daily dose. Reduction at a consumption frequency of 2 times per day was small and consistent with the linear-response line but was not statistically significant.Xylitol is a naturally occurring sugar alcohol that has been shown to markedly reduce tooth decay. The substitution of xylitol for sucrose in confections and foods may significantly decrease dental caries (for reviews see [1-3]). Published studies and prevention programs using xylitol have followed the dose and frequency of earlier studies which showed reductions in caries and where the daily xylitol dose varied from 4 to 11 g divided into three to five doses and delivered primarily via chewing gum. Studies using dose of 4 to 5 g or less of xylitol per day have reported conflicting results [4,5]. Table 1 summarizes selected published clinical trials where different formulations of xylit