Evaluation of GIC-surface treatment on bond strength of resin composites

Methods: Fuji II LC (2LC, RMGI, GC) and Fuji IX GP EXTRA (F9E, GI, GC) was filled in mold (4mm diameter, 6mm depth). 2LC was light cured immediately after filling. F9E were stored in 37^oC/100% R.H for 2min 30sec from start of mix. The bonding surface of F9E and 2LC was either formed by grinding with the #600-grit silicon carbide paper or left alone (no grinding). Their surfaces were treated by as follows; 1) G-aenial Bond (GB, GC), 2) Acid etching with G-aenial Bond (AE+GB), 3) Scotchbond Universal (SU, 3M ESPE). Then G-aenial Universal Flo was placed on the (RM)GIC surface - 2.3798mm diameter (Ultradent jig). The specimens were immersed in distilled water at 37^oC for 24hrs. Bond strength was performed with shear bond strength test (EZ-S 500N, Shimadzu, crosshead speed 1mm/min). Same letters in each 2LC groups and F9E groups indicate no statistically significant difference (Tukey's test, p<0.05).

Results: The bond strength of 2LC with #600-grid surface was lower than other groups. Significant difference was not observed among any other conditions. F9E require bonding treatment for bond but there were not significantly different among bonding treatment conditions.

Conclusions: Conventional GICs need bonding treatment to get their bonding strength. It is considered that RMGIs did not require bonding treatment if air inhibition layer exists on the surface.