Method: Two experimental resin cements were prepared by adding AER on the hydroxyl (OH) form: Control (no AER added) and Experimental (AER in OH- form). They were used to lute composite resin discs in 32 molar teeth with the adhesive systems ACE All Bond TE (ACE) or Scotchbond Universal (SCU). Resin cements and adhesive systems were applied in the self-cure mode. After 24 h, resin-dentin beams were obtained and evaluated for the µTBS, reduced modulus of elasticity (Er) and nanohardness (H) of the cement layer at two time-points: immediate and after 6 months of water storage. The µTBS, Er and H results were statistically analyzed using a 3-way Anova and Tukey’s test (α=5%).
Result: No statistically difference in µTBS was observed between the two resin cements (p>0.05), at both periods; however, higher µTBS (p=0.000) was observed for SCU groups (Control=34.6±13.2 MPa and Experimental=34.1±9.5 MPa) when compared to ACE groups (Control=26±13.8 MPa and Experimental=27.6±8.6 MPa). The adhesive systems did not influence Er at the cement layer (p>0.05). Experimental cement (SCU=10.6±1.8 GPa; ACE=10.9±1.4 GPa) obtained higher Er at the cement layer than the control cement (SCU=7.2±1.4 GPa; ACE=9.0±1.2 GPa) at 24h (p=0.000). Experimental cement obtained higher H (p=0.000) at 24h (SCU=0.40±0.1 GPa; ACE=0.53±0.1 GPa) and 6 months (SCU=0.41±0.1 GPa; ACE=0.44±0.1 GPa). Significant reduction in H was observed after 6 months (p=0.000).
Conclusion: It can be concluded that adding the AER improved the resin cement nanomechanical properties, but no difference was observed in bond strength. Water storage decreased Er and H of the cement layer. The adhesive system seems to play a role in bond strength performance of adhesively luted composite resins.