Adhesive bonding with 4-META.

Research into improved adhesion of resins to tooth substrates has found that methacrylates with both hydrophobic and hydrophilic groups, like 4-methacryloxyethyl trimellitate anhydride (4-META), enhance monomer penetration into dentin pretreated with 10% citric acid and 3% ferric chloride (10-3). Scanning and transmission electron microscope (SEM and TEM) examinations revealed the formation of a transitional zone of resin-reinforced dentin, termed the hybrid layer. The 4-META adhesive resin impregnated the exposed collagen bundles with which it entangled to create the hybrid, essential to attaining high tensile bond strengths.