Fluoride release in vitro from a resin-modified glass ionomer after exposure to NaF solutions and toothpastes

The aims of the present investigation were: (i) to study the release of flu oride from a resinmodified glass ionomer cement (Vitremer) after exposing ( "recharging") the material with NaF toothpastes and NaF solutions with diff erent fluoride concentrations, and (ii) to study the effect of covering the material with a sealant layer (glaze) in this respect. Totally 160 specime ns were made, which were placed in water for 13 weeks to receive a low fluo ride release value. The specimens were then randomely divided into 10 group s with 16 discs each. Five of the groups were exposed once a day for 7 days to one of the following fluoride agents: 0.05, 0.2 or 2% NaF solutions and slurries of two NaF toothpastes (Acta and Pepsodent). The other five group s received the same treatment twice a day. All treatments had a recharging effect. However, the 2% NaF solution resulted in significantly more fluorid e release than the other solutions and toothpastes. Treatment twice a day g ave higher total release than once a day, but the difference were only sign ificant for the 0.2 and 2% NaF solutions. With glaze material covering the specimens, almost no fluoride release was observed. However, when the glaze was removed, a burst of fluoride ocurred.