Uptake and Release of Fluoride from Fluoride-Impregnated Chewing Sticks (Miswaks) in vitro and in vivo

The purpose was to investigate the uptake and release of fluoride (F) from F-impregnated chewing sticks (miswaks). In the first series, 3-cm-long pieces were impregnated in 1, 2, 3 and 4% NaF solutions for 3 h, 1 day and 3 days (10 pieces/ test). There was a dose-response effect with respect to both impregnation time and the concentration of the F solution. In the second and third series, totally 40 miswak pieces were impregnated in 3% NaF for 1 day and 3 days; the outer layer (bark) was separated from the inner spongy part (pulp) and analyzed separately. F was released from both parts, but somewhat more was released from the bark than from the pulp; a plateau was reached at around 30 min. In vivo, 9 healthy subjects used three products for 2 min in a crossover design: (1) a miswak impregnated in 3% NaF for 1 day, (2) a miswak impregnated in 3% NaF for 3 days, and (3) 1 g of F toothpaste (containing 1,450 ppm F as NaF) on a toothbrush. The highest F concentration at the approximal area was obtained after using the miswak impregnated in 3% NaF for 3 days compared with the other products (p < 0.05 or p < 0.01). To conclude, NaF-impregnated miswaks produced a rapid release of F in vitro as well as in vivo and may be an interesting vehicle for home care use for caries prevention in countries where they are used regularly. Copyright (C) 2008 S. Karger AG, Basel.