Uptake and release of fluoride from birch and lime toothpicks.

Birch and lime toothpicks were impregnated in a 4% sodium fluoride (NaF) solution for different periods of time, viz. 30 s, 30 min and 3 d. After impregnation for 30 min, an average of 4.1 mg NaF per birch toothpick was taken up. The corresponding value for lime toothpicks was 5.1 mg. About 60% of the fluoride (F) was released within 1 h in vitro when the toothpicks were kept in water. In vivo, the concentration of F was determined in whole saliva from five adults during 30 min after using birch toothpicks immersed in a 4% NaF solution. After 2 min, the mean salivary F concentration was 2.7 mM. Impregnation of birch toothpicks in 1, 2 or 3% NaF resulted in lower F concentrations both in vitro and in vivo, with a clear dose-response effect. When comparing the use of a 4% NaF impregnated birch toothpick, a mouthrinse with 10 ml of 0.025% NaF, sucking on a F tablet containing 0.55 mg NaF, and toothbrushing with 1 g of an 0.068% F (as NaF) dentifrice--all procedures carried out in the mouth during 2 min--the highest concentration of F in saliva was obtained after using the fluoridated toothpick. Thus, NaF impregnated birch and lime toothpicks show a quick release of F in vitro as well as in vivo and may be suitable as home care products for prevention of dental caries.