EDTA Conditioning Increases the Long-term Microtensile Bond Strength to Sclerotic Dentin Mediated by Self-etch Adhesives

Purpose: To evaluate the immediate and 12-month microtensile bond strength (μTBS) of two self-etch adhesives on sclerotic dentin with or without previous EDTA conditioning. The conditioning pattern and the relative area of open dentinal tubules were also evaluated. Materials and Methods: Twenty-eight bovine incisors with naturally exposed sclerotic dentin were used. For μTBS testing, 20 teeth were divided into 4 groups (n = 5) according to the combination of the main factors: 1. adhesive (Clearfil SE Bond [CSE, Kuraray] and Adper SE Plus [ADSE, 3M Oral Care]); 2. surface treatment (previous conditioning with EDTA and previous conditioning with distilled water [DW]). The sclerotic surfaces were conditioned with either 17% EDTA or DW for 2 min prior to adhesive application. Composite buildups were constructed. Specimens were sectioned to obtain composite-dentin sticks (0.8 mm2) to be tested immediately or after 12 months (distilled water at 37°C) in tensile mode (0.5 mm/min). The conditioning pattern and the relative area of open dentinal tubules (OT) were evaluated in the remaining eight teeth. After adhesive application, the surfaces were rinsed off with acetone and ethanol. Then the surface was evaluated by SEM with image software. Data from μTBS and OT were submitted to three-way repeated measures ANOVA and data from OT were submitted to one-way repeated measures ANOVA. After, for both tests, Tukey's post-hoc test was applied (α = 0.05). Results: For both adhesives, EDTA resulted in the highest mean immediate μTBS (p = 0.002), which remained stable after 12 months of water storage (p 0.38). CSE showed higher μTBS when compared to ADSE (p = 0.001). Degradation of the mean μTBS was observed for both adhesives only in the DW groups. Adhesive application plus with EDTA conditioning increased the OT area in comparison with only adhesive application (p 0.001). Conclusion: EDTA conditioning increased the immediate microtensile bond strength in sclerotic dentin substrate and prevented degradation when associated with a self-etch adhesive. Keywords: sclerotic dentin, scanning electron microscopy, self-etch adhesives, EDTA, microtensile bond strength