Enzyme-catalyzed hydrolysis of dentin adhesives containing a new urethane-based trimethacrylate monomer

A new trimethacrylate monomer with urethane-linked groups, 1,1,1-tri-[4-(methacryloxyethylamino-carbonyloxy)-phenyl]ethane (MPE), was synthesized, characterized, and used as a comonomer in dentin adhesives. Dentin adhesives containing 2-hydroxyethyl methacrylate (HEMA, 45% w/w) and 2,2-bis[4(2-hydroxy-3-methacryloyloxy-propyloxy)-phenyl] propane (BisGMA, 30% w/w) in addition to MPE (25% w/w) were formulated with H(2)O at 0 (MPE0), 8 (MPE8), and 16 wt % water (MPE16) to simulate the wet demineralized dentin matrix and compared with controls [HEMA /BisGMA, 45/55 w/w, at 0 (C0), 8 (C8), and 16 wt % water (C16)]. The new adhesive showed a degree of double bond conversion and mechanical properties comparable with control, with good penetration into the dentin surface and a uniform adhesive/dentin interface. On exposure to porcine liver esterase, the net cumulative methacrylic acid (MAA) released from the new adhesives was dramatically (p < 0.05) decreased relative to the control, suggesting that the new monomer improves esterase resistance.