Basic study of fluoride-releasing adhesive resin for prevention of root caries: 1. Transfer of fluorine from the resin to dentin.

Release of fluoride ion from a newly-developed fluoride-releasing resin (F-resin) into phosphate buffer and incorporation of fluorine by the dentin were studied in vitro. The rate of fluoride release (amount of daily release) from a pellet of cured F-resin showed rapid decrease to 1/2 of the initial value by day 6, and then moderate decrease to 1/4 of the initial by day 30. However, the pellet continued to release fluoride at a low but constant rate for more than 520 days. In the first 30 days after F-resin was applied to the dentin surface, large amount of fluorine was concentrated within 100 mu of the subsurface dentin. With longer incubation period, the peak concentration of fluorine at the dentin surface decreased but the depth of penetration increased to about 180 mu by day 180.