Statement of Problem: Nowadays, MTA has numerous clinical applications because of desirable properties. Many teeth which are treated by MTA need final composite restorations. In this situation, the bonding between composite and MTA has the main role in retention, durability and seal of the restoration.
Purpose: Evaluation of the bond strength between MTA and composite resin and its comparison with Resin Modified Glass Ionomer (RMGI).
Materials and Method: Sixty specimens were prepared for three experimental groups of white MTA, gray MTA, and glass ionomer Fuji II LC. Ten specimens in each group were etched with 37% phosphoric acid for evaluation of the etching effect while ten specimens were not etched. All specimens were then bonded to the composite and shear bond strength test was performed, using Instron testing machine. In addition, the fractured surfaces of the samples were checked with steriomicroscope (x10). Data were analyzed by ANOVA and Tukey HSD test.
Results: The highest shear bond strength value was seen in unetched glass ionomer subgroup and there were significant differences in shear bond strength of the composite to unetched glass ionomer in comparison with the other groups (p<0.001). There were no significant differences in shear bond strength of the composite to etched and unetched white MTA, etched and unetched gray MTA, and etched glass ionomer ( p > 0.05).
Conclusion: Shear bond strength between MTA and the composite is comparable with etched glass ionomer. The etching of the RMGI surface causes a significant decrease of bond strength to the composite but it has no effect on the bond strength of MTA to Composite.