Fluoride released from orthodontic bonding agents alters the enamel surface and inhibits enamel demineralization in vitro

In this study, we examined two fluoride-releasing orthodontic agents in respect to fluoride release, enamel demineralization inhibition, as well as alterations observed on the enamel surface after their use. Fluoride release was found to occur in the highest concentrations within the first 24 hours for both materials examined. After this period, a dramatic decline in fluoride release was observed in both adhesives, and after 90 days no fluoride was detectable. Both fluoride-releasing materials showed significant differences on enamel demineralization around the brackets when compared with a conventional adhesive, and the agent with the initial higher amounts of fluoride release showed the best results. Scanning electron microscopy of the enamel surface revealed particle depositions of microglobular form, after the examined adhesives were used. These particles most likely represent deposition of calcium fluoride, a salt with clearly cariostatic properties. The results of this in vitro study show that certain fluoride-releasing orthodontic bonding systems may provide an additional degree of safety against caries susceptibility in patients with fixed appliances for a limited period.