In vitro caries inhibition at the enamel margins of glass ionomer restoratives developed for the ART approach

Objectives: To assess the ability of conventional glass ionomer cements manufactured specifically for the atraumatic restorative treatment (ART) approach to inhibit the in vitro demineralization of enamel. Methods: Twenty-four sound permanent premolar teeth, extracted for orthodontic reasons, had cervical cavities (4×2×1.5 mm3) prepared in enamel. These were restored with Fuji IX, Fuji IX GP, Ketac-Molar and Compoglass, and then thermocycled 300 times between 5–55°C before being placed in a demineralizing solution (0.1 M lactic acid with 1 g/l dissolved hydroxyapatite at pH 4.7) for four weeks. Buccolingual planoparallel sections were cut axially through the restorations, and subsequently lapped to approximately 100 μm thickness. The sections were examined with a polarized light microscope, and lesion measurements made using image analysis software. ANOVA and coefficients of variance were used to compare the findings. Results: Compoglass and Ketac-Molar showed significantly less surface erosion than did the other two cements (p<0.0001). Inhibition of enamel demineralization immediately adjacent to the restoration margins was more frequent with the glass ionomer cements (20.5–25.0%) than with Compoglass (13.0%). However, the widths of the inhibition zones varied between materials and sites. Conclusions: Fluoride ion release from the restorative materials afforded some degree of protection to the adjacent enamel against in vitro demineralization.