Purpose: To compare the shear bond strengths of composite to dentin using conventional (three-component) and simplified (two-component) adhesive systems.
Materials and methods: 100 bovine teeth were mounted in phenolic rings and ground to 600-grit to obtain 90 flat facial dentin surfaces and 10 flat facial enamel surfaces. The dentin specimens were assigned to nine treatment groups of 10 teeth each. Three groups were assigned to conventional, three-component bonding systems: All-Bond 2, OptiBond FL, and Scotchbond Multi-Purpose Plus. Six groups were assigned to simplified, two-component bonding systems: Clearfil Liner Bond 2, Fuji Bond LC, One-Step, OptiBond Solo, Prime & Bond 2.1, and Tenure Quik with Fluoride. The enamel specimens were used as the control group with Scotchbond Multi-Purpose Plus Adhesive. Each ground surface was first conditioned according to the manufacturers' directions. After rinsing, the surface of each specimen was left visibly moist prior to application of the bonding system. Each bonding system was applied according to its manufacturer's directions. The corresponding composite restorative materials were applied in 4.4 mm diameter molds to the adhesive surface and light-cured from four directions. The completed specimens were stored in water 48 hours before testing. Shear bond strengths were measured using an Instron universal testing machine. Data were subjected to one-way ANOVA and Tukey's multiple comparison test.
Results: Mean shear bond strengths of the conventional systems ranged from 16.3 to 20.6 MPa. Mean shear bond strengths of the simplified systems ranged from 14.7 to 17.4 MPa. The mean shear bond strength of the control (enamel bonding) was 21.4 MPa. The mean shear bond strengths of the conventional and simplified systems were not significantly different from each other or from the control system.