Bonding amalgam to a resin-modified glass-ionomer base

To determine which surface treatment of a resin-modified glass-ionomer (RMGI) will result in optimal bond strength to amalgam when used with an amalgam adhesive.

Fifty discs of Fuji II LC (4 mm thick) were cured in acrylic testing holders and randomly divided into 5 groups of 10 each. The surface of the glass-ionomer was treated in 1 of 5 ways: (1) no treatment (control) (2) no etch, Amalgambond (AB) primer and AB adhesive (3) citric acid etch, AB primer, and AB adhesive (per manufacturer's instructions) (4) 37.5% phosphoric acid etch, AB primer and AB adhesive, and (5) microetch, 37.5% phosphoric acid etch, AB primer and AB adhesive. Amalgam was condensed onto the treated RMGI surface. Samples were stored in water at 37 degrees C and tested at 24 hours for shear bond strength. The data was analyzed statistically by ANOVA followed by Scheffé post hoc tests for significance. Glass-ionomer discs were also treated as described in each group, sputter-coated and examined using a scanning electron microscope.

No significant improvement in bond strengths to amalgam was observed with any of the treatments of the RMGI surface. Amalgambond significantly increased the bond strength of the amalgam to the RMGI.