Caries incidence in relation to salivary mutans streptococci and fluoride varnish applications in preschool children from low- and optimal-fluoride areas.
Caries incidence during a 2-year period was studied in 4- to 5-year-old children from three areas with contrasting levels of natural fluoride (F) in the drinking water and different regimens of topical fluoride varnish applications; group A (n = 448) was from an area with a low level of F (0.1 ppm) and semi-annual applications of fluoride varnish; group B (n = 374) was from a low F area (0.1 ppm) and no fluoride varnish treatments; group C (n = 206) was from an area with optimal F (1.2 ppm) and fluoride varnish treatments. All children were clinically assessed at baseline and after 2 years according to WHO criteria. The number of salivary mutans streptococci was estimated and scored at baseline and after 2 years with the Strip mutans method. The varnish containing 0.1% F was applied every 6 months on all accessible tooth surfaces after cleaning with a pumice paste. Basic preventive care was given to all children and restorative treatment on individual indications. Higher levels (p