Effects of etching and rinsing times and salivary contamination on etched glass-ionomer cement bonded to resin composites.

This study investigated the effect of salivary contamination on glass-ionomer/resin-composite bond strength after establishment of an appropriate etching and rinsing time for the glass-ionomer cement. Three hundred and thirty samples of glass-ionomer cement (Ketac-Fil) were injected into cavities prepared in acrylic molds. Groups containing 15 samples each were etched for 0, 15, 30, or 60 sec, after which Scotchbond and either Silux or P-30 were applied and polymerized. The samples were stored under water for 24 hr at 37 degrees C and were then tested in shear. A 30-second etching time was found to be optimal when Silux and P-30 were considered together. In a similar manner, a 20-second optimal rinsing time was determined. Samples of glass-ionomer cement were then contaminated with saliva, dried, and bonded to composite resins and tested in shear as before. Significantly lower bond strengths resulted than with the uncontaminated controls. Efforts to clean contaminated samples by rinsing or re-etching failed to increase the bond strength obtained with the contaminated samples.