Effect of sonic application mode on the resin-dentin bond strength and nanoleakage of simplified self-etch adhesive

This study aims to evaluate the effect of different application modes on the immediate and 6-month resin-dentin bond strength (mu TBS) and nanoleakage in the hybrid and adhesive layers. Three 1-step self-etch adhesives (One Coat 7.0 (OC), Clearfil S-3 Bond (CS), and FuturaBond NR (FB)) were applied on a flat superficial dentin surface of 30 human molars under manual mode or sonic vibration at a frequency of 170 Hz (SV). Composite build-ups were constructed incrementally; specimens were sectioned to obtain resin-dentin sticks with cross-sectional area of 0.8 mm(2) and tested in tension (0.5 mm/min) immediately (IM) or after 6 months (6M) of water storage. Two bonded sticks, from each tooth at each storage time, were immersed in a silver nitrate solution, photo-developed, and analyzed under scanning electron microscopy. The amount of nanoleakage was measured using the ImageTool 3.0 software. Data, from each adhesive, were analyzed by two-way ANOVA and Tukey's test (alpha = 0.05). OC and CS showed higher mu TBS and lower nanoleakage in the IM period when applied with SV groups. For FB, no significant difference was observed between the two modes of application. All materials showed lower nanoleakage in the SV groups. Higher nanoleakage was observed after 6M for OC and FB. The sonic application mode at an oscillating frequency of 170 Hz can improve the resin-dentin mu TBS, reduce the nanoleakage, and retard the degradation of the resin-dentin mu TBS of Clearfil S-3 Bond and One Coat 7.0 adhesives. Sonic application mode at an oscillating frequency of 170 Hz can be helpful and easy to use in dental practice to guaranty long-lasting restorations.