Method: Ninety-one 10-day-old Wistar rats were divided into 4 groups (n=19-26/group): Group 1 (negative control), placebo dentifrice (without F or abrasive); group 2, dentifrice containing 1,500 ppmF as MFP and CaCO3 (45%) as abrasive; group 3, dentifrice containing 1,500 ppmF as NaF and silica as abrasive; group 4, dentifrice containing 1,500 ppmF as MFP and silica as abrasive. Fresh slurries (1.0 g dentifrice, 3.0 mL deionized water) were administered once/day by gastrogavage from days 10 to 15 in a dose corresponding to 1.0 mgF/day/kg body weight. Two hours after the last gavage, animals were euthanized and plasma and femur were collected. F was analyzed with the electrode after hexamethyldisiloxane-facilitated diffusion. Data were analyzed by Kruskal-Wallis and Dunn’s test.
Result: Mean (±SD) plasma F concentrations were 0.009±0.003, 0.030±0.015, 0.030±0.020 and 0.052±0.030 µg/mL for groups 1, 2, 3 and 4, respectively. Femur F concentrations were 15.69±7.29, 60.70±22.47, 70.07±25.55 and 51.95±35.09 µg/g, respectively. All experimental groups significantly differed from placebo but did not significantly differ from each other, except for the significant difference found between groups 3 and 4 for plasma.
Conclusion: F bioavailability was not influenced by the type of F compound nor by the type of abrasive system in dentifrices. Thus, health organizations should not endorse the addition of higher amounts of F to MFP/CaCO3 formulations based on the assumption that F from them is less bioavailable.