Fluoride concentration, mutans streptococci and lactobacilli in plaque from old glass ionomer fillings

Previous studies have found that the fluoride concentration of plaque growing on or adjacent to glass ionomer cement (GIC) is increased and the proportion of mutans streptococci in plaque is reduced. So far, there are only a few studies of the long-term effect of glass ionomer fillings on plaque in vivo. The aim of this study was to determine whether old GIC fillings have effects on plaque fluoride and microflora and whether this effect can be increased by topical application of fluoride on GIC fillings in vivo. The participants were 27 adults with at least 3 GIC fillings about 3 years old. Plaque was collected from sites adjacent to the GIC fillings and from the contralateral teeth, after which a 1.2% fluoride gel was applied to all teeth. Three days later, plaque was collected from the same sites as before. Stimulated saliva was also collected at both appointments. The results show that none of the patients had elevated levels of fluoride in their saliva either before or 3 days after the fluoride treatment. The fluoride concentration was 0.51 microgram/mg protein in plaque on GICs and 0.35 microgram/mg protein in plaque on contralateral teeth (p = 0.028). After the fluoride treatment, the respective fluoride concentrations were 0.59 microgram/mg and 0.75 microgram/mg (p = 0.849). No significant differences in the proportion of mutans streptococci and lactobacilli in plaque from GIC and contralateral teeth were found. The results suggest that the fluoride concentration of plaque growing on old GIC fillings is slightly increased. In this study, however, this had no significant effect on the cariogenic microflora.(ABSTRACT TRUNCATED AT 250 WORDS)