Resistance of ten contemporary adhesives to resin-dentine bond degradation

Objectives: To evaluate resin-dentine bond degradation after 1 year of water storage. Methods: Human dentine surfaces were bonded with two etch-and-rinse self-priming adhesives (Single Bond/SB and Prime & Bond NT/PBNT), three 2-step self-etching adhesives (Clearfil SE Bond/SEB, Resulcin Aqua Prime/RES and Non-Rinse Conditioner with Prime & Bond NT/NRC-PBNT), and five 1-step self-etching adhesives (Etch & Prime 3.0/EP, Prompt L-Pop/PLP, Solist/SOL, Futurabond/FUT and AQ Bond/AQ). Adhesives were applied according to manufacturers' instructions. Composite build-ups were constructed and the bonded teeth were stored (24 h, 6 months, 1 year) in distilled water at 37 °C. After storage, the intact teeth were sectioned into beams and all specimens were tested for microtensile bond strengths (MTBS). ANOVA and multiple comparisons tests were applied at α = 0.05. Fractographic analysis of debonded beams was performed using scanning electron microscopy. Results: SB, PBNT and SEB attained the highest MTBS, regardless of the storage period. A significant decrease in MTBS was observed after 6 months for SOL. After 12 months the only groups that did not reduce bond strength were SB and SEB. Bonded specimens in NRC-PBNT, RES and FUT produced pre-testing failures after 12 months, and MTBS could not be measured. Conclusions: The resistance of resin-dentine bonds to degradation is material-dependent. When the enamel-resin interface is preserved, the etch-and-rinse adhesives and the mild 2-step self-etch adhesive SEB exhibited the best resin-dentine bond durability. Those tested self-etching adhesives having a pH ≤ 1 and using water or acetone as solvent attained catastrophic bond failure after 1 year of water storage.