FLUORIDE RELEASE PROFILES OF RESTORATIVE GLASS-IONOMER FORMULATIONS

Objectives. The amounts of fluoride released by different glass ionome r formulations were compared on the basis of individual fluoride relea se profiles in order to derive the effect of the physical and chemical formulation on the fluoride release process. Methods. The fluoride re lease profiles of each of five specimens of ten glass ionomer cements setting by an acid-base reaction were investigated. The profiles were obtained by determining the amount of fluoride released [F] after equi librating the samples at 37 degrees C in distilled water for 140 d. Th e {[f],t}-profiles were compared with a Multivariate Data Analysis on the basis of a Principal Component Analysis. Results. The Multivariate Data Analysis reveals that eight of the ten glass ionomers can be cla ssified into four distinct groups. When the cumulative amount of fluor ide released by each sample, [F](c), is calculated and fitted as a fun ction of time, a regression analysis (r > 0.99) reveals that [F](c) fo r all samples is most adequately represented by [F](c) = ([f](l).t)/(t +t(1/2)) + B .root t, indicating that two kinetic processes are respon sible for the fluoride release profiles. Significance. A comparison of the parameters of this equation shows that the physicochemical ration ale for the classification of the glass ionomers conforms to differenc es in the kinetics of these processes which are determined by the qual itative and quantitative chemical composition as well as by the presen tation (hand mixed vs. capsules) of the glass ionomer. From the classi fication, it becomes apparent that different formulations can result i n the same fluoride release profiles.