Shear Bond Strength of Resin Modified Glass Ionomer Cement Bonded to Different Tooth-Colored Restorative Materials

The aim of this study was to determine in vitro the shear bond strength (MPa) and the type of bond failure when resin-modified glass ionomer cement (RMGIC) was bonded with different tooth-colored restorative materials.The RMGIC tested was Fuji II LC (FL) and the tooth-colored restorative materials used were composite resin Point-4 (P4), Compomer Dyract AP (DY), and Ormocere Admira (AD). A total number of 60 FL specimens were prepared using Teflon molds. The specimens were divided into six equal groups. Each group of ten specimens was bonded to a tested tooth-colored restorative material as follows: Group I--etched FL bonded to P4; Group II--non-etched FL bonded to P4; Group III--etched FL bonded to DY; Group IV--non-etched FL bonded to DY; Group V--etched FL bonded to AD; and Group VI--non-etched FL bonded to AD. The specimens were stored in distilled water at 37 degrees C for 24 hours. The shear bond strength was measured in a universal testing machine, and the fractured surfaces were examined under a stereomicroscope.The results of the shear bond strength indicated the lowest mean value (14.46 MPa) was in Group III, and this was significantly different from the values of other groups (p<0.05). However, Groups V and VI recorded the highest mean values (24.5 MPa and 28.39 MPa) which were significantly different (p<0.05) when compared to other groups. Groups I, II, and IV showed no significant difference with mean values of 20.06, 19.99, and 20.1 MPa which were significantly different from other groups (p<0.05).AD showed the highest shear bond strength to RMGIC. All groups demonstrated a cohesive failure in FL except for Group IV where a cohesive failure in DY was recorded. AD showed good shear bond strength when laminated with FL.