The hybrid layer: a resin-dentin composite.

During studies designed to improve the bonding of adhesive resins to tooth structure, it was found that methacrylates with both hydrophobic and hydrophilic groups promoted monomer penetration into suitably prepared dentin. The monomers impregnated and became entangled with the collagen fibrils of surface demineralized dentin, creating a hybrid layer after their polymerization. The identification, properties and function of the hybrid layer, a new biologic composite, are explained.