The Effect of Different Decontamination Methods on the Micro-Tensile Bond Strength of CAD/CAM Resin-Based Blocks to Resin Cement.

Introduction: This study evaluates the impact of decontamination methods on Microtensile bond strength (μTBS) between resin cement and resin blocks.

Methods: Twenty CAD/CAM resin blocks from two manufacturers were wet-polished, sandblasted, and ultrasonically cleaned. After blood and saliva contamination, blocks were divided into subgroups: control, water rinsing, acid etching, alkaline cleaning paste, or 10-MDP containing cleaner. Resin-based cement was then applied. After 24 hours, the blocks were sectioned to obtain bars for testing. Half of the specimens were tested immediately for μTBS, and the other half underwent artificial aging. The surfaces of the blocks were inspected with a scanning electron microscope (SEM). Three-way ANOVA was performed for μTBS values (α=0.05).

Results: In one of the substrates, the positive control subgroup obtained the highest value (56,01 MPa, SD:6,96) followed by 10-MDP cleaner and universal cleaning paste, when immediately tested, with significant differences respect to the water rinsing (p⟨0.041) and acid etching (p⟨0.048) groups. After thermocycling, higher values were found in the 10-MDP cleaner (47,57 MPa, SD:8,15), but differences were not significant. In the other substrate group, the 10-MDP cleaner subgroup showed highest bond strengths (64,46 MPa SD: 10,92) at the initial test. After thermocycling, 10-MDP cleaner (58,66 MPa, SD: 9,93) gave the highest μTBS value. Significant differences between water rinsing group and the rest of subgroups (p⟨0.001), and between 10-MDP cleaner and the positive control group (p⟨0.006) were observed.

Conclusion: Cleaning after contamination improves bonding. 10-MDP containing cleaner can help to restore initial μTBS value and maintain it in the long-term.