Effect of fluoride gels on micromorphology of resin-modified glass-ionomercements and polyacid-modified resin composites

Objective: The purpose of this study was to evaluate the surface micromorph ology of resin-modified glass-ionomer cements and polyacid-modified resin c omposites subjected to a neutral sodium fluoride (NNaF) and an acidulated p hosphate fluoride (APF) gel application. Method and materials: Thirty stand ardized cylindric specimens were randomly obtained from each of two resin-m odified glass-ionomer cements-Fuji II LC Improved and Photac-Fil Aplicap-an d two polyacid-modified resin composites-Dyract and F2000-amounting to 120 samples. After 1 week, the specimens were finished and polished with alumin um oxide disks. Surface treatments with fluoride gels, or distilled water a s a control, were performed four times, interspersed with eight pH cycles, simulating high cariogenic challenges. Five calibrated evaluators assessed the surface micromorphology through photomicrographs. Results: The Kruskal- Wallis test showed no significant difference between the control and experi mental groups for Fuji II LC Improved and Dyract. Photac-Fil Aplicap showed less micromorphologic change as a result of distilled water application, u nlike the NNaF and APF treatments, which revealed no significant difference from each other. For F2000, there was no significant difference between th e surfaces treated by NNaF and distilled water; the highest degradation occ urred with the APF Conclusion: Both the resin-modified glass-ionomer cement s and the polyacid-modified resin composites showed erratic behaviors conce rning their micromorphology when subjected to fluoride gel application.