Objective.  The aim of this study was to investigate the effect of a fixed daily dose of xylitol on mutans streptococci in saliva and the amount of visible dental plaque. A second aim was to explore if the possible effects differed between children with and without caries experience.

Methods.  The study was designed as a double-blind randomized controlled trial with two parallel arms. All pupils (n = 149) in grades 1–6 in a comprehensive school in northern Sweden were invited, and 128 children (mean age = 12.7 years) consented to participate. The children were stratified as having caries experience (DMFS/dmfs ≥ 1) or not before the random allocation to a test or control group. The control group (A) was given two pellets containing sorbitol and maltitol three times daily for 4 weeks, and the test group (B) received corresponding pellets with xylitol as single sweetener (total dose = 6.18 g day). Clinical scoring and saliva samples were collected at baseline and immediately after the test period. The outcome measures were visible plaque index, salivary mutans streptococci counts and salivary lactic acid production.

Results.  The amount of visible plaque was significantly reduced in both groups after 4 weeks (P < 0.05). Likewise, the sucrose-induced lactic acid formation in saliva diminished in both groups (P < 0.05). The proportion of mutans streptococci decreased significantly in the test group compared to baseline, but not in the control group (P < 0.05). The alterations in the test group seemed most prominent among children without previous caries experience.

Conclusions.  The results suggest that chewing gum with xylitol or sorbitol/maltitol can reduce the amount of dental plaque and acid production in saliva in schoolchildren, but only the xylitol-containing gum may also interfere with the microbial composition.