Shear Bond Strength of a Light-Cured Veneering Composite to Fiber-Reinforced Composite Substrates

Purpose: The aim of this study was to compare the shear bond strength of a veneering composite to 2 differently treated fiber-reinforced composite (FRC) substrates and to a base metal alloy. Materials and Methods: A veneering composite (SR Adoro) was bonded to the following substrates: (1) a nickel-chromium base metal alloy (control, group A), (2) an FRC substructure (Vectris) with a flat surface (group B), and (3) an FRC substructure (Vectris) with retentive rods 0.5 X 0.5 mm in cross section and 10 mm in length, positioned parallel to each other at a distance of 0.5 mm (group C). Thirty-nine specimens were fabricated and divided into 3 groups of equal size. All specimens were thermocycled for 5,000 cycles at 5°C and 55°C with dwell time of 30 seconds in each bath. Evaluation of shear bond strength was performed at a constant crosshead speed of 0.5 mm/min according to ISO 10477. Results: The mean values for the shear bond strength were 19.29 MPa for the control group (group A), 16.66 MPa for group B, and 16.74 MPa for group C. Despite a tendency to higher bond strength of group A specimens, no statistically significant difference was recorded between the groups (P > .05). Conclusions: No statistically significant difference was found between the metal and FRC substructures. Retentive rods on the FRC substructure do not seem to increase the bond strength significantly.