Effects of long-term water storage on the microtensile bond strength of five experimental self-etching adhesives based on surfactants rather than HEMA.

Objectives: The purpose of this study is to evaluate the hypothesis that replacing 2-hydroxyethyl methacrylate (HEMA) for surfactant dimethacrylates (SD) does not affect the immediate and long-term microtensile bond strength (μTBS) of experimental two-step self-etch HEMA-free adhesive systems applied on dentin. Materials and methods: Five experimental HEMA-free two-step self-etching systems containing different SD (ethoxylated bisphenol A diglycidyl dimethacrylate (Bis-EMA 10, B10), Bis-EMA 30 (B30), poly-ethyleneglycol (400) dimethacrylate (PEG 400, P400), PEG 1000 (P1000), and PEG 400 urethane dimethacrylate (UDMA) (UP400)) and a HEMA-containing system (control) (HA) were formulated. Specimens were subjected to the μTBS test after 24 h and 6 and 12 months of storage. Data (in megapascals) were analyzed by Kruskal-Wallis and Dunn tests ( α = 0.05). Results: Medians of the μTBS data after 24 h of storage are: HA = 57.2, B10 = 26.2, B30 = 24.0, P400 = 32.6, P1000 = 37.3, and UP400 = 57.9; after 6 months are: HA = 47.9, B10 = 18.5, B30 = 7.8, P400 = 16.1, P1000 = 14.6, and UP400 = 51.6; and after 12 months are: HA = 31.2, B10 = 15.2, B30 = 9.0, P400 = 9.1, P1000 = 13.3, and UP400 = 35.7. Between the HEMA-free groups, the adhesive system formulated with PEG 400 UDMA produced similar μTBS to the HEMA-containing group. Also, the storage of specimens decreased the μTBS ( p < 0.05). Conclusion: Replacing HEMA for PEG 400 UDMA in an adhesive system formulation generated a satisfactory μTBS to dentin. Clinical relevance: Surfactant dimethacrylates have a potential use in the development of HEMA-free self-etching adhesive systems, which are more chemically stable. [ABSTRACT FROM AUTHOR]