Resin-modified glass ionomer cements: a comparison of water sorption characteristics

The purpose of this study was to quantify and compare the amount of water absorbed by six commercially available resin-modified glass ionomer cements and to investigate the possible influence of time and resin content on water sorption. The materials evaluated included Variglass used as a restoration, base and liner; Fuji II LC; Fuji Liner; Vitrebond; Vitremer and Photac-Bond. Z100, a composite resin, was used as control. All specimens were manipulated according to manufacturers' instructions and then subjected to a water sorption test based on the ISO 4049 requirements. Storage in water was further extended to 1 month to evaluate the effects of time and indirectly cement maturity on water sorption. Data were subjected to one-way ANOVA and Duncan's test at 0.05 significance level. Results show that the composite resin control had significantly less water sorption than all the resin-modified polyalkenoate cements evaluated. Variglass when used as a base or restorative had the least water sorption after both 1 week and 1 month storage in water. The degree of water sorption was product dependent and appeared to be influenced by the resin (HEMA) content. The results also reflect a potential relationship between time (cement maturity) and water sorption.