Influence of application parameters on bond strength of "an all in one" water-based self-etching primer/adhesive after 6 and 12 months of water aging

Our aim was to evaluate the influence of different application parameters on microtensile bond strength (μTBS) of an all in one water-based self-etching primer/adhesive to dentin. Extracted human third molars had their crowns transversally sectioned next to the dentinoenamel junction. Prompt-L-Pop adhesive was applied using five modes: (1) following the manufacturer's instructions (MI); (2) after 36% H₃PO₄ etching (15 s) (AG); (3) after H₃PO₄ etching and 5% NaOCl (2 min) with constant agitation (HG); (4) as a double layer (DL); and (5) for double the application time (DT). Resin build-ups were constructed with Tetric Ceram. After storage for 24 h, 6 months, or 12 months in water at 37°C, the specimens were vertically sectioned into beams (cross-sectional areas, 1 mm²). Each beam was tested in an Instron Machine at 0.5 mm/min. Analysis of variance and Student-Newman-Keuls were used (P < 0.05). Bonded interfaces were examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The highest μTBS values were obtained when AG was used, and the lowest when MI was employed. The HG, DL, and DT modes resulted in similar μTBS values. Water storage reduced μTBS in all groups except the MI group. SEM and TEM revealed hybrid layer and resin tag formation in all groups. Applied after AG, HG, DL, and DT, Prompt L-Pop adhesive provided adequate bond strength to dentin after 24 h of water storage. Bond strength decreased when specimens were stored in distilled water for 6 or 12 months.