Hybrid Layer as a Dentin-Bonding Mechanism


  • Presented at the First International Conference on Adhesive Dentistry. Los Angeles, California. January 11-12, 1991.

Address reprint requests to Dr. Nobuo Nakabayashi. Institute for Medical and Dental Engineering. Tokyo Medical and Dental University 2-3-10. Surugadai, Kanda, Chiyoda-Ku, Tokyo, Japan


A number of mechanisms (both mechanical and chemical) have been proposed as the cause of dentin adhesion. Extensive research in Japan during the past 10 years has shown that strong, long-lived bonds between resin and living dentin will form when a monomer such as 4-META, which contains both hydrophilic and hydrophobic chemical groups, penetrates the tissue and polymerizes in situ. This resin-impregnation creates a transitional “hybrid” layer, that is neither resin nor tooth, but a hybrid of the two. The thin layer of resin-reinforced dentin locks the two dissimilar substances together on a molecular level, sealing the surface against leakage and imparting a high degree of acid resistance.