Resin-modified glass-ionomer restorations and in vitro secondary caries formation in coronal enamel

Objective: The purpose of this laboratory study was to compare the effects of a resin-modified glass ionomer and a resin composite restorative materia l on secondary caries formation in coronal enamel. Method and materials: Tw elve caries-free molars were sectioned into tooth quarters. Coronal cavitie s were prepared and then restored with either a resin-modified glass-ionome r material (mesiobuccal and mesiolingual tooth quarters), or a resin compos ite (distobuccal and distolingual tooth quarters). Caries like lesions were created, and secondary caries was examined by polarized light microscopy f ollowing lesion initiation and progression periods. Results: The resin-modi fied glass-ionomer specimens had significantly shallower primary surface le sions at both the lesion initiation (35% shallower) and progression (45% sh allower) periods than did the resin composite specimens. There were signifi cantly fewer wall lesions (3-fold and 2-fold fewer following lesion initiat ion and progression, respectively) in the resin-modified glass-ionomer grou p than in the resin composite group. Conclusion: Resin-modified glass-ionom er restorations reduce the susceptibility of unrestored adjacent enamel sur faces and cavosurfaces to a constant cariogenic challenge. The caries resis tance imparted to the surface enamel and cavosurface is most likely due to the fluoride release from the resin-modified glass-ionomer material.