Effect of self-curing activators and curing protocols on adhesive properties of universal adhesives bonded to dual-cured composites

•Dual-cured 2-step self-etch adhesive is recommended for buildup restorations with dual-cured resin composites.•The in vitro behavior of universal adhesives depends on the curing more and the specific composition of each adhesive.•In general, the dentin sealing ability worsens after water storage for all adhesives.

ObjectivesTo measure microshear bond strength (μSBS) and nanoleakage (NL) of self-etch universal adhesives under core buildup restorations using different curing protocols, at 24 h and after 6-month water storage.MethodsMiddle dentin of 55 molars was divided into: Clearfil Universal Bond [CFU], Prime&Bond Elect [PBE], and One Coat 7 Universal [OCU]. All-Bond Universal [ABU] and Clearfil SE Bond [CSE] were used as control. CFU, PBE and OCU were: light-cured [LC], dual-cured [DC] and self-cured [SC]. Data were analyzed separately (two-way ANOVA), Tukey's test (α = 0.05).ResultsμSBS: At 24 h OCU/LC resulted in statistically higher μSBS than ABU. CSE/DC showed statistically higher μSBS than all DC adhesives. PBE/LC resulted in significant lower μSBS than the respective DC/SC modes (p < 0.001). At 6-month, both CFU and PBE (LC/SC), resulted in a significant decrease in μSBS. μSBS for OCU/DC decreased significantly (p < 0.001) compared to the respective LC/SC modes. NL: At 24 h, ABU showed %NL similar to CBU/LC and OCU/LC (p > 0.05). CSE/DC resulted in significantly higher %NL than OCU/DC but significantly lower than PBE/DC. CFU/LC/SC resulted in significantly lower %NL than CFU/DC. PBE/SC resulted in significant lower %NL than PBE/LC and PBE/DC. OCU/LC and OCU/DC resulted in significant lower %NL than OCU/SC (p < 0.001). At 6-month ABU, CSE, CFU/LC and CFU/SC, resulted in a significant increase in %NL.SignificanceSelf-cured activator and different curing protocols influenced μSBS and NL of self-etch universal adhesives, but this influence was material-dependent.