Effects of etching time on surface morphology and adhesion of a posterior resin to glass-ionomer cement.

This study examined the effects of etching time on surface morphology and adhesion of posterior composite resin to glass-ionomer cement. Three glass-ionomer cements and four etch times were studied. Bond shear strength results revealed significant differences by both cement and etch time. Glass-ionomer surfaces etched for 30 seconds produced the strongest bond to resin. Ketac-Silver cement provided greater shear resistance than either Ketac-Bond cement or GC lining cement. Scanning electron microscopy revealed greater surface roughness for etched versus unetched glass ionomer. However, no subsurface differences were noted with increased etch times. These findings indicate that 30 seconds is the optimal etch time for glass-ionomer cement and that Ketac-Silver cement provides the strongest bond to resin of any of the materials tested. Etched glass-ionomer subsurfaces did not reveal marked differentiation in morphology, suggesting that an alternative method is necessary to detect these differences.