Recent developments in dentin bonding

Hybridization of the dentin with resin by monomer interdiffusion has been identified as the basic bonding mechanism resulting in an intimate interlocking of the cured resin with the dentin. Today, growing efforts are made to simplify and shorten the bonding procedures, e.g. by combining the functions of primer and adhesive. Ultrastructural investigations using high-resolution optical technology provided exciting insight into the interactions of bonding systems and dentin. It became clear, that the maintenance or recovery of microporosities in the dentin is most important for optimal hybridization. This can be achieved by the moist bonding technique, which is mandatory in acetone-based systems. The observation that certain bonding systems are able to bond to dentin depleted from the demineralized collagen network raised the question of whether the collagen-resin interdiffusion zone really represents a prerequisite for successful bonding to dentin. The use of strongly acidic primer monomers introduced the concept of "self-etching" primers not only to dentin but also to enamel, which eliminates the necessity of a separate conditioning step. Clinical investigations are necessary to evaluate the potential of recently developed all-in-one products which combine the functions of conditioner, primer, and adhesive. With improvements in dentin bonding and the development of new resins that exhibit little or no shrinkage upon polymerization, even greater applications for adhesive technology will be found in dentistry.