Objective: This study aimed to compare dentin bond durability under different degradation conditions between two etch-and-rinse (ER) systems and a universal adhesive in ER mode. Method: This study used a universal adhesive [Scotchbond Universal (SU)], a three-step ER adhesive [Scotchbond Multi-Purpose Plus (SM)], and a two-step ER adhesive [Single Bond Plus (SB)]. A phosphoric acid-etching agent was applied to bovine dentin prior to the application of either a primer or the adhesive. After acid etching, bonding procedures were conducted. The specimens were divided into three group classes: (1) subjected to 10,000, 30,000, or 50,000 thermal cycles (TC); (2) stored in distilled water at 37 °C for 6 months or 1 year (WS); and (3) stored in distilled water for 24 h (baseline). Shear bond strength (SBS) tests were conducted. Results: SB showed a higher baseline SBS than the other adhesives. Defining the baseline SBS value for each adhesive system as 100%, TC groups ranged from 56.1 to 70.3% for SM, from 98.4 to 103.7% for SB, and from 120.3 to 126.7% for SU. WS groups ranged from 66.2 to 71.4% for SM, from 98.1 to 103.3% for SB, and from 102.5 to 118.1% for SU. Conclusions: Although SB showed relatively stable dentin bond performance under all degradation conditions, SM showed decreased dentin SBS with prolonged degradation. SU did not show any significant decrease in SBS from the baseline under any degradation condition. Clinical relevance: The universal adhesive showed comparable adhesive performance with the two-step ER adhesive.
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