Fluoride bioavailability in saliva and plaque

Eight trained volunteers brushed their teeth in the morning for 3 minutes with either NaF or amine fluoride, and saliva and 3-day-plaque-regrowth was collected at 5 time intervals during 6 hours after tooth brushing. The amount of collected saliva and plaque was measured, and the fluoride content was analysed using a fluoride sensitive electrode. All subjects repeated all study cycles 5 times, and 3 cycles per subject underwent statistical analysis using the Wilcoxon-Mann-Whitney test.Immediately after brushing the fluoride concentration in saliva increased rapidly and dropped to the baseline level after 360 minutes. No difference was found between NaF and amine fluoride. All plaque fluoride levels were elevated after 30 minutes until 120 minutes after tooth brushing, and decreasing after 360 minutes to baseline. According to the highly individual profile of fluoride in saliva and plaque, both levels of bioavailability correlated for the first 30 minutes, and the fluoride content of saliva and plaque was back to baseline after 6 hours.Fluoride levels in saliva and plaque are interindividually highly variable. However, no significant difference in bioavailability between NaF and amine fluoride, in saliva, or in plaque was found.Already two decades ago it has been postulated that site-specific aspects of salivary fluoride clearance may have important implications for the site-specificity of oral diseases [1]. It is now well known that at least three factors are influencing this site-specificity of oral pathobiology: the different local composition and pathogenicity of oral biofilms (local microbiome), the site-specific host response towards bacterial phylotypes as commensals or pathogens (local immunity), and finally, the individual variability of salivary and plaque clearance of fluoride.Whereas the first two factors are exclusively in the focus of basic research, the kinetics of fluoride in oral fluids are rather well documented. This is the reason why clinical reco