Effect of a neutral citrate solution on the fluoride release of resin-modified glass ionomer and polyacid-modified composite resin cements

The effect of 0.01 mol/l citrate solution at pH = 7 on the fluoride release is compared for the resin-modified glass ionomer cements (RM-GIC) GC Linin g LC, PhotacBond, Vitremer and Vitrebond and for the polyacid-modified comp osite resins (PAM-C) Variglass and Dyract by means of the six-month fluorid e release profiles at 37 degrees C. The fluoride release of both RM-GIC and PAM-C increases in the neutral citrate solution as compared to water, whic h can be explained by the ability of citrate to complex metal ions and henc e to degrade the glass as well as the polysalt matrix of the cement. Althou gh RM-GIC release more fluoride than PAM-C in water as well as in citrate s olution, the relative increase in fluoride release upon immersion in citrat e solution is most pronounced for PAM-C. Whereas for the latter citrate aff ects both the short-term and long-term fluoride release, for RM-GIC only th e long-term fluoride release is affected. This suggests that the action of citrate increases with decreasing importance of the polysalt formation in t he hardening of the material. This could be explained on the basis of the d ifference in the chemical properties of the cement matrix. (C) 2000 Elsevie r Science Ltd. All rights reserved.