Comparative Evaluation of Microtensile Dentin Bond Strength and Interfacial Micromorphology of Three Universal Adhesives.

Objectives: To assess and compare the microtensile dentin bond strength (μTBS) and interfacial micromorphology of three universal adhesives.

Methods: 96 human molars were assigned to three universal adhesives: Single Bond Universal (SBU), CLEARFIL Universal Bond Quick (UBQ), and RE-GEN Universal Adhesive (REGEN). Adhesives were applied in self-etch mode. SBU and REGEN were applied following the manufacturers' instructions. UBQ was divided into two subgroups: one following the manufacturer's instructions (UBQ Short) and the other with an extended application time (UBQ Extended). Teeth were restored with nanohybrid resin composite. Specimens were divided into immediate and delayed subgroups. The delayed subgroups were stored for 6 months and subjected to 5000 thermocycles. μTBS was tested, and failure mode was analyzed. Interfacial micromorphology was assessed using a scanning electron microscope. The data were statistically analyzed (p⟨ 0.05).

Results: The adhesive choice, aging, and their interaction significantly affected μTBS. SBU exhibited the highest immediate μTBS, comparable to UBQ (Extended) and REGEN, and significantly higher than UBQ (Short). In delayed testing, SBU outperformed the other adhesives.

Conclusions: Aging negatively affected the μTBS of UBQ and REGEN, while SBU wasn't affected. The quick application concept of UBQ deteriorated its μTBS compared to the extended application time.