COMPARATIVE IN-VITRO MICRORADIOGRAPHIC EFFECTS OF RESIN-MODIFIED AND AUTOPOLYMERIZING GLASS IONOMERS ON DEMINERALIZATION OF PRIMARY AND PERMANENT ENAMEL

The purpose of this study was to compare in vitro effects of resin-mod ified and autopolymerizing glass ionomer restorative materials on demi neralization of primary and permanent human enamel. Thirty primary and permanent enamel specimens measuring approximately 3 x 4 x 4 mm were sectioned and piano-paralleled before random placement of materials: P hotac-Fil, a resin-modified glass ionomer; Ketac-Fil, an autopolymeriz ing glass ionomer; and Tytin, a silver amalgam. After incubation for t wenty-four hours, the samples were pH cycled for eight hours at pH 5.0 and sixteen hours at pH 7.2 for a total of two weeks, all at;37 degre es C. The specimens were then subjected to an artificial caries challe nge at pH 5.0 for 196 hours. The specimens were embedded in Epon 812 a nd incubated at 55 degrees C for thirty-six hows. Microsections were p roduced from each sample and subjected to microradiography and quantit ative microdensitometry. Data on lesion depth and mineral content were analyzed by Two Way ANOVA and Student Newman-Keuls Pairwise Multiple Comparison tests. There were significant differences in lesion depth a nd mineral content between groups (p<0.05) and between permanent and p rimary enamel. This study demonstrates that Photac-Fil and Ketac-Fil p revent in vitro demineralization at varying levels in primary and perm anent enamel.