Combined effects of sucrose and fluoride on experimental caries and on the associated microbial plaque

In an experimental model, slabs of sound and presoftened bovine enamel were worn in the human mouth for seven days except for periodic removal for in vitro exposure to experimental variables. Supplementation with 3% sucrose for 10 minutes, four times daily for seven days yielded predicted levels of experimental caries. Parallel exposure to 3% sucrose containing 100 ppm fluoride sharply reduced or negated the resultant caries in originally sound enamel, and reversed the simulated pre-experimental caries in most samples of presoftened enamel. Serial layers of test enamel surfaces showed high levels of fluoride accumulated in the originally sound enamel, and even higher levels in the presoftened enamel that had been suppemented with sucrose-fluoride solution. Quantitation of the plaqye microbial flora showed that the fluoride ion exerted no detectable influence. Consistent with the findings in previous studies, some correlation appeared to exist between the degree of experimental caries and that proportion of total plaque that was comprised of S salivarius. S mutans, or lactobacilli.