Chemical aspects of self-etching enamel–dentin adhesives: A systematic review

The paper gives an overview on the components and the polymer chemical aspects of currently used self-etching enamel–dentin primers/adhesives. In addition, the contribution of new adhesives monomers and cross-linkers exhibiting enhanced hydrolytic stability than methacrylates to improve the performance of single-bottle adhesives is discussed. Information from original scientific papers or reviews about enamel–dentin adhesives, the patent literature concerning dental adhesives and manufacturer information of commercial self-etching adhesives were included in this review. The most efficient self-etching enamel–dentin adhesives are based on strongly acidic adhesive monomers, containing dihydrogenphosphate, phosphonic acids or carboxylic acid groups. Serious problems of single-bottle water-based, strongly acidic self-etching enamel–dentin adhesives arise both from the hydrolytic instability of the methacrylate monomers used and the side reaction of the applied initiator components. The stability of the self-etching enamel–dentin adhesives can be improved by using new acrylic ether phosphonic acids or mono- or difunctional acrylamides, while more stable and compatible components have to be developed in the future.