Effect of acetic acid on the fluoride release profiles of restorative glass ionomer cements

Abstract

Objectives. This study investigates the fluoride release of glass ionomers in an acetic acid solution in order to substantiate a model according to which the short-term release results from an elution of loosely bound fluoride and the long-term release from an erosive leaching of the glass particles in the bulk of the cement. Methods. Individual fluoride release profiles of five specimens of 10 acid–base setting restorative glass ionomers were obtained by determining the amounts of fluoride released by each sample at 37°C in consecutive elutions for up to 140 days with 25 ml of a 0.01 mol/l acetic acid solution with pH=4. Differences in the fluoride release profiles were determined with a Multivariate Data Analysis on the basis of a Principal Component Analysis. Results. The fluoride release profiles of the 10 glass ionomers can be classified into five distinct groups which are characterized by a cumulative fluoride release described by the equation [ F] c=[ F] I t/( t+ t 1/2)+ β√ t. The parameters ([ F] I, t 1/2) and β are characteristic for the materials in the groups, and refer to the short-term and long-term fluoride release, respectively. The acidic solution enhances both processes compared to an elution in water, the effect being more pronounced for the long-term release. Significance. The fluoride release mechanism is intrinsically the same as determined for elutions in water. The increased amount of fluoride released under acidic conditions, especially in the long term, corroborates that an erosive leaching of the glass particles in the bulk of the cement accounts for the long-term fluoride release.