Purpose: To determine the influence of the relative enamel abrasivity (REA) of fluoridated toothpaste on the uptake of
KOH-soluble and structurally bound fluoride into enamel.
Materials and Methods: Bovine enamel samples were randomly allocated to 6 groups (n = 36 per group). Groups A to
C were treated with sodium fluoride (NaF) toothpastes and groups D to F with amine fluoride (AmF) toothpastes
(1500 ppm F each). The REA in groups A and D was 2, in groups B and E it was 6 and in groups C and F it was 9. Twice
a day, 18 samples of each group were immersed for 2 min in a slurry (toothpaste:artificial saliva = 1:3), while the remaining
samples were brushed with the respective slurry (2.5 N force; 60 strokes/min; 2 min). All samples were stored
at 37°C and 100% humidity. After five days, the amount of KOH-soluble and structurally bound fluoride was determined
and statistically compared by Scheffe’s post-hoc tests.
Results: REA value and mode of application (immersion or brushing) had no significant influence on the amount of either
kind of fluoride from NaF toothpastes. Only for the NaF toothpaste with REA 6 was the amount of KOH-soluble
fluoride significantly higher after brushing. With AmF toothpastes, KOH-soluble and structurally bound fluoride concentrations
were significantly higher when the samples were brushed. Furthermore, in the REA-2 group, the amounts of
KOH-soluble fluoride (brushed or immersed) and structurally bound fluoride (brushed) were significantly higher than in
the other groups.
Conclusion: The REA dependency of KOH-soluble and structurally bound fluoride was found only for the AmF toothpastes.
Using AmF toothpaste, the mode of application influenced the uptake of KOH-soluble and structurally bound
fluoride into enamel.