New trends in dentin/enamel adhesion

The acid-etch-technique has provided an ideal surface for bonding to enamel by using 30-40% phosphoric acid. The resulting etch pattern is characteriz ed by the profuse formation of microporosities which allow the penetration of monomers into those porosities to form resin tags that provide micromech anical retention. Successful attempts of bonding to dentin in a similar fas hion have been reported more recently. Due to the specific properties of de ntin, such as its tubular structure and its intrinsic wetness, bonding to d entin has not yet reached the ideal characteristics. In spite of the existi ng deficiencies in dentin adhesion, the increasing demand for esthetic rest orations has generated intensive research on new esthetic materials with sp ecial focus on amalgam alternatives. The bonding mechanism of recent dentin bonding agents is based on the penetration of ambiphilic molecules into ac id-etched dentin to form a lacework of dentin collagen and polymerized mono mers. Dentin adhesive systems that contain a multitude of different bottles of different colors and shapes belong to the past. Because clinicians are increasingly eager to try new materials, the actual tendency calls for simp lification of the bonding procedure e.g. one-bottle adhesive systems and al l-in-one no-bottle materials. In spite of simpler materials, a separate etc hing step is still needed for one-bottle systems. Nevertheless, manufacture rs of these simplified one-bottle materials recommend their use to bond pol yacid-modified composites (compomers) without a separate etching step. The most recent addition to the group of simplified adhesives is the all-in-one no-bottle adhesives; one of these all-in-one systems, Prompt L-Pop (ESPE) has resulted in very promising laboratory results when used on enamel. In s pite of the uncertainty about the capacity of all-in-one adhesives to etch enamel adequately in vivo, scanning electron microscopy studies have result ed in an enamel-etching pattern morphologically similar to that correspondi ng to phosphoric acid-etched enamel. While all-in-one adhesive systems have been reported to result in very satisfactory dentin bond strengths, result s from other laboratories suggest that bonding to dentin with all-in-one ad hesive systems will need to be somewhat improved. Clinical studies, which a re the ultimate test for the acceptance of dentin adhesives, are now underw ay in several centers. Six-month data showed a very good clinical performan ce for this ultra-simplified ail-in-one adhesive system.