4-META as an acidic monomer in an all-in-one experimental adhesive

This article describes a clinical study of an experimental, all-in-one, self-etching priming enamel and dentin adhesive. This new compound is a hydroxyethylmethacrylate (HEMA)-free resin mixture of urethane dimethacrylate (UDMA) and 4-methacryloxyethyl trimellitate anhydride (4-META) dissolved in acetone and water. The pH of the adhesive solution is 2.2, which classifies this material as moderately strong. Bond strengths to enamel and dentin are approximately 20 MPa. The marginal inspection of bonded resin composite restorations in 3.5-mm wide, cylindrical, butt-joint dentin cavities reveals gap-free intact margins in 6 of 8 cases. Scanning electron microscopy analysis of the bonding interface to enamel shows a shallow microretentive etching pattern, and dentin is hybridized to a depth of approximately 1 micron. The fracture morphology analyzed on debonded shear strength specimens illustrates cohesive failure in resin close to the enamel and dentin bonding interfaces.