Nanoleakage and microtensile bond strength at the adhesive-dentin interface after different etching times

Purpose: To evaluate the effect of etching time on the nanoleakage and microtensile bond strength (mu TBS) at the interface between etch-and-rise adhesives and dentin. Methods: Eighty molars were sectioned to expose the superficial dentin and randomly divided into four groups according to the adhesives used: OptiBond Solo (OB), Single Bond (SB), One-Step (OS), and Prime&Bond NT (PB). Within each group, a total-etching technique was applied, and the dentin surfaces were etched for 0, 15, 30 or 60 seconds. Each treated tooth was then sectioned into sticks. A non-trimming mu TBS test and TEM observation for nanoleakage were sequentially performed. Results: The degree of nanoleakage increased as etching time increased (P< 0.05). For the OS and PB groups, the highest mu TBS values were achieved with 15 seconds of etching, followed by 30, 60 and 0 seconds. For the OB and SB groups, the mu TBS values for 15- and 30-second etching times were similar and were both significantly higher than those of 0 and 60 seconds (P<0.05). (Am J Dent 2010;23:335-340).