Long-term fluoride release of visible light-activated composites in vitro: a correlation with in situ demineralisation data.

Fluoridated composites are able to reduce or inhibit secondary caries around fillings. The aims of this study were firstly to investigate the amount of F released in vitro from composites with a F content between 0 and 26 vol% as a function of time over a 1-year period. A second aim was to correlate the in vitro data on F release with enamel demineralisation data in situ after a 1-month period. The results show that all fluoridated composites release sizable amounts of F in solution, the total amounts of F released from three composites were proportional to log t over at least 1 year. In one case proportionality of the total amount of F released with t was observed. Possible mechanisms of F release are considered. The results presented also show a linear relation between the log of in vitro F release data and the effects on enamel demineralisation in situ next to the composite. Extrapolation of the data reveals that a F release of about 200-300 micrograms/cm2 over a 1-month period from a fluoridated composite would completely inhibit secondary caries under plaque conditions.