In vitro fluoride release from aesthetic restorative materials following recharging with APF gel

In this in vitro study, the fluoride ion release from three more-viscous co nventional glass ionomer cements (GICs) - ChemFlex, Fuji IX GP, Ionofil Mol ar - four polyacid-modified resin composites (compomers) - Dyract AP, Compo glass F, Freedom, F2000 - and a hybrid resin composite - Ariston pHc - were compared. The amounts of fluoride release from 3x2.7mm specimens were meas ured over six weeks using a fluoride ion-selective electrode. After six wee ks, the specimens were recharged with 2ml of 1.23 per cent acidulated phosp hate fluoride (APF) gel for four minutes. The recharged specimens were then assessed for the amounts of fluoride release over another six weeks. Stati stical analyses were performed using one-way and repeated measures ANOVA. T he GICs and Compoglass F showed significantly higher initial fluoride relea se rates during the first two days (p<0.05). After the first two days, fluo ride release rates from all materials dropped quickly and became essentiall y stabilized within three-five weeks, in an exponential mode. The rechargin g of the specimens with APF gel caused a brief, but significant, increase i n fluoride release for all materials (p<0.05), before decreasing to previou s comparable rates. Compoglass F released relatively more fluoride, and Ari ston pHc relatively less, after APF gel application than before. The lowest total amounts over the study were released by Dyract AP and Freedom. The n ewer compomers, as well as the newer more-viscous GICs, appear to act as fl uoride reservoirs to varying extents.