Incorporation into human enamel of fluoride slowly released from a sealant in vivo

Fluoride incorporation into human enamel from an experimental sealant resin in vivo was investigated. The sealant consisted of a newly synthesized methacryloyl fluoride-methyl methacrylate (MF-MMA) copolymer resin, which contains acidic fluoride covalently bonded to carbonyl groups and releases fluoride ions slowly by hydrolysis in an aqueous environment. This experimental sealant was applied to the enamel of permanent pre-molars and the control sealant without MF-MMA copolymer to that of the contralateral teeth. Fluoride concentration was determined by an enamel biopsy procedure with acid-etching four weeks after the sealant application. As much as 3500 ppm fluoride was found to be deposited at 10 microns depth in the enamel under the MF-MMA copolymer sealant. The increase in fluoride concentration was significant even at 60 microns. Of the fluoride incorporated into the enamel, from 70 to 80% was present as a tightly bound form. This resin sealant is expected to protect the enamel from caries attack even after detachment of the sealant.