Effect of Adhesive Strategy on Microtensile Bond Strength of CAD/CAM Composite to Dentin

Objectives: The aim of this study was to evaluate the effect of adhesive strategy and time on microtensile bond strength of a CAD/CAM resin composite to dentin.
Methods: Sixty CAD/CAM resin composite blocks were bonded to human dentin with simplified bonding agents using etch-and-rinse and self-etching approaches and amine-based and amine-free resin cements, with and without the application of a dual cure activator (DCA) (n=10): SBP-ARC (Adper Single Bond Plus + RelyX ARC), SBP-RXU (Adper Single Bond Plus + RelyX Ultimate), SBP-DCA-RXU (Adper Single Bond Plus + DCA + RelyX Ultimate), SBU-ARC (Scotchbond Universal + RelyX ARC), SBU-RXU (Scotchbond Universal + RelyX Ultimate) and SBU-DCA-ARC (Scotchbond Universal + DCA + RelyX ARC). Each specimen was light-cured for 40 s under load and stored in distilled water at 37°C for seven days . Stick-shaped specimens (1.0 mm² area) were obtained, and half of the specimens underwent microtensile bond strength testing, ≤and the other half were subjected to the same tests after six months of storage. Failure mode was determined using an optical microscope (40 ×). The data were analyzed by a two-way ANOVA followed by the Games-Howell test and Student’s T-test (α=5%).


Results: After seven days, SBU-RXU presented the highest mean bond strength, only statistically different from SBU-ARC (p≤0.05). Most of the groups exhibited statistically significant reduction in bond strength after 6 months (p≤0.05), except SBP-RXU and SBU-ARC (p≥0.05). The most common type of failure in all the groups at both time points was the mixed failure.

Conclusions: The adhesive strategy, with different associations between adhesives and resin cements, as well as the use of a dual-cure activator, affected the bond strength of both amine-free and amine-based resin cements to a CAD/CAM composite.