Purpose: To evaluate the microshear bond strength (μSBS) of several universal adhesive systems applied on five
different indirect restorative materials.
Materials and Methods: Five CAD/CAM materials were selected: 1) indirect resin composite (LAV); 2) feldspathic
glass ceramic (VTR); 3) leucite-reinforced glass-ceramic (EMP); 4) lithium disilicate ceramic (EMX); 5) yttrium-stabilized
zirconium dioxide (CZI). For each material, 15 blocks were cut into 4 rectangular sections (6 × 6 × 6 mm)
(n = 60 per group), and processed as recommended by the respective manufacturer. For each indirect material, the
following adhesive systems were applied according to the respective manufacturer’s instructions: 1) AdheSE Universal
[ADU]; 2) All-Bond Universal (ABU); 3) Ambar Universal (AMB); 4) Clearfil Universal (CFU); 5) Futurabond U
(FBU); 6) One Coat 7 Universal (OCU); 7) Peak Universal Bond (PUB); 8) Prime&Bond Elect (PBE); 9) Scotchbond
Universal Adhesive (SBU); 10) Xeno Select (XEN, negative control). After the application of the adhesive system,
cylinder-shaped transparent matrices were filled with a dual-curing resin cement (NX3) and light cured. Specimens
were stored in water (37ºC for 24 h) and tested in shear mode at 1.0 mm/min (mSBS). The failure pattern and
μSBS were statistically evaluated (a = 0.05).
Results: LAV, VTR, and EMP showed a greater number of cohesive fractures than EMX and CZI (p < 0.0001). PUB
was the only adhesive for which the mean μSBS reached the highest ranking of statistical significance for all five
substrates. When each adhesive was compared across the five substrates, 8 out of 10 (ADU, ABU, AMB, CFU,
OCU, PUB, PBE, and SBU) reached the statistically highest mean μSBS when applied on CZI.
Conclusion: The specific chemical composition of universal adhesives was not the decisive factor in the bond
strength values measured for different CAD/CAM indirect materials. There was a wide variability in mean μSBS
when different universal adhesives were applied to the several CAD/CAM indirect materials. Most universal adhesives
bonded well to air-abraded zirconia.