Plaque [F] After Using a NaF or Placebo Dentifrice in a Non-fluoridated Community

This 4-week, double-blind, double-crossover study with 16 11-to-15-year-old Brazilian children was done to compare the whole saliva and plaque fluoride concentrations ([F]) associated with the use of a NaF (FD, 1000 ppm F) or F-free placebo (PD) dentifrice. A second objective was to determine the relationship between the plaque concentrations of F and calcium ([Ca]). The protocol was similar to that presented last year (AADR Abst 1618, 2001) except that the subjects were children and their drinking water had a low [F] (< 0.1 ppm). The children used the FD or PD alternately at weekly intervals. At bedtime on the 6th day of each week, the children brushed only the occlusal surfaces of their teeth to allow the accumulation of smooth-surface plaque. They were instructed not to brush again until after saliva and plaque (half mouth) had been collected the next morning immediately after which they brushed the occlusal surfaces for 1.0 min and additional collections were made 1.0 h later. Thus, the collections were made 1.0 h and approximately 12 h after having used the FD or PD. F and Ca were analyzed using the electrode after HMDS-diffusion and by AAS, respectively. The salivary [F] 1 h and 12 h after using the FD (10.4 and 4.6 µmol/L) were significantly higher than those after using the PD (1.0 µmol/L). The plaque [F] 1 h after using the FD (10.2 mmol/kg dry wt) was significantly higher than the 12-h [F] (5.1 mmol/kg) and both of these were significantly higher than the 1-h and 12-h PD [F] (2.8 and 2.2 mmol/kg). Thus, in this non-fluoridated community plaque [F] were consistently higher when the FD was used. These plaque [F], however, ranged from 55% to 79% lower (p < 0.01) than those of adults whose drinking water was optimally fluoridated (AADR Abst 1618, 2001) while the plaque [Ca] of the two studies did not differ significantly. To the extent that the results from these two studies can be compared, they suggest that fluoridated water contributes more than 50% as much fluoride to plaque as a fluoridated dentifrice. In agreement with last year’s findings, there was a strong correlation between plaque [Ca] and [F] under all experimental conditions (p=0.0001).