Abstract
This investigation was done to determine the bioavailability of fluoride (F) after toothbrushing associated with different water rinsing procedures. Eight adult subjects participated in four experiments, conducted with a randomised, crossover design: (A) 2 min brushing with an F dentifrice, followed by three quick (3×2 s) rinses, each with 10 ml of water; (B) brushing as in A followed by one long-lasting (1 min) rinse with 5 ml of water combined with the toothpaste-saliva mixture; (C) brushing as in A followed by expectoration but without any water rinse afterwards; and (D) ingestion of the toothpaste as a slurry with 100 ml of de-ionized water. Blood samples were collected before and frequently for 6 h after each experiment and analyzed for F content. The area under the plasma F concentration vs. time curves (AUC) was calculated and the degree of F absorption estimated. AUC values obtained in experiment D were assumed to represent 100% F bioavailability. The plasma values recorded during experiment A were not significantly greater than the baseline values, indicating almost no F absorption when 3 quick water rinses were performed after toothbrushing. The degrees of F absorption after one long-lasting water rinse (B) were 7.6 ± 4.2% and with no water rinse after toothbrushing (C) 23.8±13.5%, respectively. The results showed that the degree of F absorption after toothbrushing using an F toothpaste is strongly related to the mode of water rinsing.