Introduction Dentin bonding or adhesion is the micro-mechanical union of restorative materials to dentin, particularly dental composites, via an intermediary adhesive resin layer. Kramer and McLean (1952) were among the first to use glycerophosphoric acid dimethacrylate (GPDM) to bond to dentin. They notice altered staining of the tissue surface during histologic examination of the area that is presently known as the hybrid layer. Over the last 40 years, major advances have been made in both adhesive monomer formulations and in pre-treatment of dentin to improve resin penetration into the tissue matrix. Definitions ADHESION Adhesion refers to the attraction between the atoms and molecules at the contacting surfaces of different materials. An intermediate material, an adhesive, can be used to bond two objects together. Chemical bonding (ionic bonds), physical forces (van der Waals '), and mechanical interlocking also. Good wetting …show more content…
A similar phenomenon was first described in vitro for enamel by Gwinnett and Buonocore (1965).This process of infiltrating resin monomer into the collagen fibrillar matrix of demineralized dentin, followed by its polymerization, has been called hybridization (Nakabayashi et akl, 1982) and has been shown to exist in vivo (Gwinnett and Kanca, 1992b; Nakabayashi et al, 1992) WETTING Wetting is a general term used to indicate the ability of a liquid to come into intimate contact with a solid substrate (Huntsberger, 1964, Zisman, 1964) A liquid is said to wet the solid substrate if its contact angle (Young Equation) is less than 900. Effective wetting or intimate contact must occur between the liquid adhesive and the conditioned dentin surface to obtain a good adhesive bonding. The Composition of the Smear Layer and Its Role in