Two-year bond strengths of "all-in-one" adhesives to dentine

Objectives: To test the long-term in vitro bonding performance of "all-in-one" self-etch adhesives to dentine. Methods: Adper Prompt (3M ESPE), Bond Force (Tokuyama), Brush & Bond (Parkell), iBond Self Etch (Heraeus Kulzer), OptiBond All-In-One (Kerr), and Xeno IV (Dentsply Caulk) were tested. The two-step self-etch adhesive Clearfil SE Bond (Kuraray) served as the control. Extracted human teeth were assigned to groups after creation of smear layer on occlusal dentine. Adhesives were applied according to manufacturers' instructions, and resin composite (Filtek Z250, 3M ESPE) build-ups were placed. The bonded specimens were sectioned into beams after 24 h of storage in water. Microtensile bond strengths (μTBS) was determined at baseline, and following one and two years of water storage using an EZ-Test device (Shimadzu). Representative specimens were examined under field emission scanning electron microscope. Fracture mode was recorded. The data were analyzed using linear mixed effects and least square means analyses. The significance level was set at 0.01 for the pairwise comparisons and at 0.05 for the overall model effects. Results: The mean μTBS decreased significantly over time for Adper Prompt, iBond Self Etch, and OptiBond All-In-One. After two years of water ageing, Bond Force, Brush & Bond, OptiBond All-In-One, and Xeno IV had mean μTBS values not statistically different from Clearfil SE Bond. Conclusions: After two years of water ageing, Clearfil SE Bond outperformed two of six all-in-one adhesives. That indicates that the composition of the adhesives rather than their application approach is accountable for their performance. Clinical significance: Despite the data available suggesting that most all-in-one adhesives are severely affected by hydrolytic degradation, results of the present in vitro study suggest that some may perform as well as the clinically proven Clearfil SE Bond in the longer term.