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-modified and autopolymerizing glass ionomer restorative materials on demineralization of primary and permanent human enamel. Thirty primary and permanent enamel specimens measuring approximately 3 x 4 x 4 mm were sectioned and plano-paralleled before random placement of materials: Photac-Fil, a resin-modified glass ionomer; Ketac-Fil, an autopolymerizing glass ionomer; and Tytin, a silver amalgam. After incubation for twenty-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 degrees C. The specimens were then subjected to an artificial caries challenge at pH 5.0 for 196 hours. The specimens were embeded in Epon 812 and incubated at 55 degrees C for thirty-six hours. Microsections were produced from each sample and subjected to microradiography and quantitative 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 and mineral content between groups (p < 0.05) and between permanent and primary enamel. This study demonstrates that Photac-Fil and Ketac-Fil prevent in vitro demineralization at varying levels in primary and permanent enamel.