Multiparameter evaluation of acrylamide HEMA alternative monomers in 2-step adhesives

As frequently added to adhesives, the mono-functional monomer 2-hydroxyethyl methacrylate (HEMA) acts as co-solvent and improves surface wetting. Nevertheless, HEMA promotes watersorption hydrolysis at adhesive interfaces, affecting bond durability dentin. This study investigated if two acrylamide co-monomer alternatives could replace in experimental adhesive-resin formulations part of 3/2-step universal adhesives applied, respectively, etch-and-rinse (E&R) self-etch (SE) bonding modes. Upon priming dentin with 10-MDP-based Clearfil SE Bond 2’ primer (‘C-SE2p’; Kuraray Noritake), three resins, consisting 50 wt.% Bis-GMA, 15 TEGDMA, either 35 diethyl (‘DEAA’), hydroxyethyl (‘HEAA’) or (‘HEMA+’), were applied. The control HEMA-free resin contained 60 Bis-GMA 40 TEGDMA (‘HEMA?’). All evaluated for ‘immediate’ ‘aged’ micro-tensile strength (?TBS) upon, 1-week (1w) 6-month (6m) water storage, TEM adhesive-dentin interfacial interaction, 24-h 6m three-point bending, contact-angle wetting, viscosity watersorption. Linear mixed-effects model statistics revealed significantly better performance applied E&R than mode, except DEAA_1w, highest ?TBSs recorded DEAA HEMA? mode. In aging did not reduce DEAA’s ?TBS. Best wetting on primed was HEMA+, DEAA, further HEAA HEMA?, these directly related their viscosity. absorbed more all other formulations. HEMA?>DEAA>HEAA>HEMA+ significant order bending strength. HEMA, while not.