Fluoride Bioavailability in the Tongue Coating and Oral Floor Biofilm

Method: The tongue coating of five volunteers was removed using a commercially available tongue cleaner. The oral floor biofilm was collected using Periopaper (Oraflow Inc). All subjects brushed their teeth with amine fluoride containing dentifrice. Specimens were collected before, immediately, 30 and 120 minutes after tooth brushing. Fluoride concentration in all specimens was determined according standard procedures using a fluoride sensitive electrode (Orion 96-09, Thermo Electron). Data of single comparisons were evaluated statistically using the sign test for dependent variables. For Multiple comparisons of the mouth floor measurements one way ANOVA with Bonferroni correction was used.

Result: In the tongue coating fluoride concentration after tooth brushing increased about 12 fold above the baseline. After 30 minutes it decreased to double fold and stayed about this value until 120 minutes. The difference between the baseline and the endpoint measurement was statistically significant (p= 0.002). No significant differences were found in the measurements of the oral floor biofilm.

Conclusion: The results are in accordance with previous results which showed dramatic increase of the fluoride concentration after tooth brushing in the supernatant saliva and salivary sediment with a following decrease. However, the fluoride concentration in the tongue coating remains at a double fold higher level compared to the baseline up to 120 minutes post brushing. This may indicate that the tongue coating is a major reservoir for the fluoride bioavailability. The results also support the unequal fluoride distribution in the oral cavity.