Physical properties of resin-modified glass-ionomers

The physical properties and shear bond strength of two resin-modified glass-ionomers: RMGIs (FJL and VT) and as a control, a conventional glass-ionomer: CGI (FJ), were evaluated. Ninety percent of the setting shrinkage under dry conditions and nominal hygroscopic expansion in water during 360 h occurred within the first 24 h. The nominal hygroscopic expansion of CGI was 0.38% while the RMGIs demonstrated over 1%, but considering the setting shrinkage the total hygroscopic expansion of CGI and the RMGIs were over 7 times and about 2.5 times, respectively. The thermal expansion of the RMGIs after water immersion was greater than that under dry condition. In contrast, FJ demonstrated expansion less than under dry condition. There was no significant difference between FJL and VT (P < 0.05) as regard water absorption. The shear bond strength of the RMGIs to enamel and dentin were superior to FJ, except for VT to dentin.