Xylitol consumption decreases counts of mutans streptococci. However, the mechanism behind this decrease is not well understood. We studied not only type strains and clinical isolates of mutans streptococci, but also other polysaccharide-forming oral streptococci. Growth inhibition and adherence of cells to a smooth glass surface-reflecting synthesis of water-insoluble polysaccharides were studied in the presence of 2% (0.13 mol/l) and 4% (0.26 mol/l) xylitol. The effect of xylitol was compared to a novel polyol sweetener, erythritol. Except for Streptococcus mutans 10449 and S. sobrinus OMZ 176, the glass surface adhesion of most polysaccharide-forming streptococci was reduced by the presence of both 4% xylitol and erythritol. For the S. mutans and S. sobrinus type strains, the growth inhibition with 4% xylitol and erythritol was 36-77% and for the clinical S. mutans isolates 13-73%. Of the other oral streptococci, only S. sanguinis was inhibited with 4% xylitol (45-55%). For both polyols, the magnitude of the growth inhibition observed was not associated with the magnitude of the decrease in adherence (xylitol: r = -0.18; erythritol: r = 0.49). In conclusion, both xylitol and erythritol can decrease polysaccharide-mediated cell adherence contributing to plaque accumulation through a mechanism not dependent on growth inhibition.

Aim. To reveal the additional value of radiographic bitewings (BW) in detection of caries and in comparing the occurrence of clinically undetected severe decay between 14-year olds with and without clinically observed dentinal caries in a low-caries prevalence population. Design. The cross-sectional study used 363 pairs of radiographs read by one examiner without knowledge of the clinical findings. The yield was analyzed on a tooth surface level by cross tabulating the clinical and radiographic information and on an individual level by counting the number of yield surfaces for all subjects. Mann-Whitney U test was used. Results. On a tooth surface level, the contribution of BW was the greatest on the occlusal surfaces of the first molars, where established or severe dentinal decay was registered in BW in 11% of clinically sound surfaces and in 40% of established cavitated enamel lesions. On an individual level, 53% of subjects benefited from BW. The subjects clinically DMFS > 0 benefited more than the clinically DMFS = 0 subjects (P = .004), nearly 60% in relation to 47%, respectively. Conclusions. In a low-caries prevalence population a remarkable portion of both clinically DMFS = 0 and DMFS > 0 14-year olds benefit from BW examination. Most of the benefit is obtained on the occlusal surfaces of the first and the second permanent molars.