shear bond strength evaluation of resin composite to resin-modified glass-ionomer cement using three different resin adhesives vs. glass-ionomer based adhesive

Background: the clinical success of sandwich technique depends on the strength of resinmodified glass ionomer cement (rmgic) bonding to both dentin and resin composite. therefore, the shear bond strength (sbs) of resin composite bonded to rmgic utilizing different resin adhesives versus a gicbased adhesive was compared. materials and methods: in this in vitro study, 84 holes (5×2 mm) were prepared in acrylic blocks, randomly divided into seven groups (n=12) and filled with rmgic (lightcured universal restorative, gc). in the group i; no adhesive was applied on the rmgic. in the group ii, nonetched and group iii was etched with phosphoric acid. in groups ii and iii, after rinsing, etchandrinse adhesive (optibond solo plus); in the group iv; a twostep selfetch adhesive (optibond xtr) and in group v; a onestep selfetch (optibond allinone) were applied on the cement surfaces. group vi; a gicbased adhesive (fuji bond lc) was painted over the cement surface and cured. group vii; the gicbased adhesive was brushed over rmgic followed by the placement of resin composite and cocured. afterward; resin composite (point 4) cylinders were placed on the treated cement surfaces. the specimens were placed in 100% humidity at 37 ± 1°c and thermo cycled. the shear bond test was performed at a crosshead speed of 1 mm/min and calculated in mpa; the specimens were examined to determine mode of failure. the results were analyzed using oneway anova and tukey test. results: the maximum (24.62±3.70 mpa) and minimum (18.15±3.38 mpa) sbs mean values were recorded for optibond xtr adhesive and the control group, respectively. the pairwise comparisons showed no significant differences between the groups that bonded with different adhesives. the adhesive failure was the most common failure mode observed. conclusion: this study suggests that gic-based adhesive could be applied over rmgic as cocure technique for sandwich restorations in lieu of employing the resin adhesives