Low-fluoride Dentifrice and the Effect of Rinsing on Salivary fluoride

Post-brushing water rinsing may reduce the risk of fluoride (F) ingestion from dentifrice but the decreased salivary F bioavailability may jeopardize the consequent anticaries benefits. Objective: Since the use of low-F concentration dentifrices is still a matter of debate, this study aimed to compare the salivary F bioavailability after brushing with a conventional F dentifrice followed by a water rinse and after brushing with a low-F dentifrice without post-brushing rinse. Methods: In a crossover, blind study, F concentration in saliva of five adult volunteers was determined after brushing, during 1 min, with 1.0 g of a low-F dentifrice (500 µg F/g) or with a conventional F concentration dentifrice (1100 µg F/g) followed, or not, by a 15-mL distilled water rinse. Samples of non stimulated saliva were collected on times: before and immediately after brushing, and after 1, 2, 3, 4, 5, 10, 15, 20, 30, 45 and 60 min. F concentration was determined by a microanalytical technique using a F electrode and the area under curve of F salivary concentration X time (µg F/mL x min^-1) was calculated. Results: Salivary F bioavailability was 2.5 times reduced when water rinse was used (P<.05), irrespective of dentifrice concentration, and it was 2 times lower for the low-F dentifrice (P<.05). Also, the salivary F bioavailability was similar when the low-F dentifrice was used without post-brushing rinse and the conventional F dentifrice was followed by a rinse (P>.05). Conclusion: The results suggest that habits of post-brushing rinse should be taken into account on the recommendation of dentifrice use by young children, considering the risks and benefits balance of F.

Supported by FAPESP (05/04703-0)