Six months of daily high-dose xylitol in high-risk schoolchildren: a randomized clinical trial on plaque pH and salivary mutans streptococci.

A randomized clinical trial was designed to evaluate the effect of daily high-dose xylitol chewing gum on plaque pH and salivary mutans streptococci (MS) in a sample of schoolchildren at high risk of caries. The study was performed on 204 subjects (acceptance rate 88.3%). Inclusion criteria were: >1 and <4 carious lesions, and a salivary MS concentration >10(5) CFU/ml. Subjects were randomly assigned to the xylitol or control group. Study design included one examination at baseline (t(0)), one after 3 months of chewing (t(1)), one after 6 months of chewing (t(2)) and the last 3 months after the end of chewing period (t(3)). Plaque pH was assessed using the MicroTouch technique, following a sucrose challenge. The area under the curve (AUC(5.7) and AUC(6.2)) was recorded. Whole saliva was collected in sterile vials and MS CFU/ml were counted. Data were analysed using repeated-measures ANOVA. The main result was that plaque acidogenicity was reduced in both groups. The differences between treatments were statistically significant both for plaque pH and MS concentration; the interaction term for treatment and time was statistically significant (p < 0.01). At t(2), the xylitol group children with a salivary MS concentration >10(5) and those with < or =10(5) showed significantly lower AUC(5.7) and AUC(6.2) values than the control group. These results suggest that the long-term use of high-dose non-sucrose chewing gums had beneficial effects on plaque pH, and that this effect was statistically greater when using xylitol chewing gums, both on plaque pH and MS salivary concentration.