Effect of Xylitol-Wipe on Mutans Streptococci Virulence

Title: Effect of Xylitol-Wipe on Mutans Streptococci VirulencePurpose: In a randomized clinical trial, we found a significant reduction of new caries in young children with daily use of xylitol-wipes over one year without reduction on mutans streptococci (MS) levels. The purpose of this study was to determine whether the use of xylitol-wipes for one year was due to selection of xylitol-resistant MS, altered the rate of acid production of MS and/or altered biofilm formation ability of MS. Methods: Unique MS genotypes were isolated from the xylitol-wipe group and the placebo-wipe group at baseline and at 1 year. These isolates were examined for their xylitol sensitivity, rate of acid production and ability to form biofilm. Xylitol sensitivity was determined by comparing bacterial growth curves in TPY glucose broth with or without the addition of 1% xylitol. Acid production was monitored by the means of pH drop for 30 minutes after each isolate was grown in the presence of glucose. Sucrose dependent biofilm formation of each genotype was quantified using crystal violet assay.Results: At one year, there was no significant difference in prevalence of xylitol-resistant MS genotypes between the xylitol-wipe and the placebo-wipe groups. There was significant decrease difference in plateau pH within each group from baseline to 1 year (p<0.05). The change in acid profile in the xylitol-wipe group from baseline to 1 year was similar to that observed in the caries vs. no caries group. There were no statistical significant differences in biofilm formation of MS isolated from the two wipe groups at baseline or one year (p>0.05). Conclusions: This prospective randomized clinic trial has shown no correlation between caries reduction and selection of xylitol-resistant MS. Furthermore, xylitol-wipe use did not alter the ability of MS to form biofilm. However, there is evidence to suggest that after one year xylitol wipe use would select MS with decrease acid production ability. Future studies are needed to identify other possible mechanisms of caries prevention resulting from the use of xylitol-wipes in children