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Principles of enamel etching.

Amongst the innovations that have changed the practice of dentistry over the past three decades, the acid-etch technique and the use of composite resins may be regarded as two of the most influential. In 1955, Michael Buonocore, a researcher at the Eastmen Dental Centre in Rochester, New York, made the astute observation that the application of weak inorganic acid could alter the surface enamel so that bonding of a resin to the surface could take place. Buonocore experimented with acrylic resins but found these were much too weak to withstand the stresses exerted upon them in the mouth. It was not until Rafael Bowen developed a unique system containing 25 percent by weight of polymerisable monomer and 75 percent by weight of a vitreous filler--the composite resin--that the acid-etch technique became an effect procedure. This article reviews historical and current research, in the search to optimise the resin to enamel bond.