Optimization of a validated protocol that determines bioavailable fluoride in toothpastes.

A validated protocol used to determine how much of total fluoride is bioavailable in toothpaste formulations was evaluated if it could be simplified regarding the following parameters: (i) concentration of the slurry (0.25-4%), (ii) centrifugation speed (1,000-12,000 g) and time (1-10 min) and (iii) incubation time for FPO32- ion hydrolysis and insoluble-F dissolution (15-60 min). Fresh and aged Na2FPO3/CaCO3 and fresh NaF/SiO2 based toothpastes were analyzed (n=9). The improvements were: the centrifugation at 1,000 g for 5 min is enough to separate insoluble-F and the time for FPO32- ion hydrolysis and insoluble-F dissolution can be shortened to 30 min.