Oral fluoride measurements for estimation of the anti-caries efficacy of fluoride treatments.

The aims of this work were (a) to assess the oral bioavailability of fluoride delivered from dentifrices and (b) to test for a possible link between the results and clinical data obtained with the same dentifrices. Oral fluoride concentrations were measured in samples of saliva and plaque taken from seven subjects, after use of dentifrices which contained 0, 1000, 1500, and 2500 micrograms F/g as sodium monofluorophosphate. Salivary fluoride in samples obtained within the first few hours after a single dentifrice application, or up to 20 h after four weeks' daily use, increased with increasing F content of the dentifrice. For example, the mean zero-time intercepts of the second phase of salivary fluoride clearance curves for the above dentifrices were 0.46, 1.48, 1.88, and 3.03 mumol F/L, respectively. Plaque fluoride measured after four weeks' daily use of the dentifrices exhibited similar dose-response behavior. Linear regression analysis showed these trends to be statistically significant for both saliva (p less than 0.001) and plaque (p less than 0.025). Mean saliva and plaque fluoride concentrations were inversely associated with mean three-year caries increments for the three fluoride-containing dentifrices obtained in a recent clinical trial: DMFS scores 6.80, 6.33, and 5.71, respectively (Stephen et al., 1988). This suggests that oral fluoride measurements are a valuable in vivo method for the evaluation of the potential anti-caries efficacy of fluoride-containing dental products.