A review of the developments of self-etching primers and adhesives -Effects of acidic adhesive monomers and polymerization initiators on bonding to ground, smear layer-covered teeth

Abstract

This paper reviews the developments of self-etching primers and adhesives, with a special focus on the effect of acidic adhesive monomers and polymerization initiators on bonding to ground, smear layer-covered teeth. Ionized acidic adhesive monomers chemically interact with tooth substrates and facilitate good bonding to ground dentin. Polymerization initiators in self-etching primers further promote effective bonding to ground dentin. To promote bonding to both dentin and enamel, phosphonic acid monomers such as 6-methacryloyloxyhexyl phosphonoacetate (6-MHPA) were developed. These novel adhesive monomers also have a water-soluble nature and are hence endowed with sufficient demineralization capability. A new single-bottle, self-etching, 2-hydroxyethyl methacrylate (HEMA)-free adhesive comprising 6-MHPA and 4-acryloyloxyethoxycarbonylphthalic acid (4-AET) was developed. This novel adhesive enabled strong adhesion to both ground enamel and dentin, but its formulation stability was influenced by pH value of the adhesive. To develop hydrolytically stable, single-bottle, self-etching adhesives, hydrolytically stable, radical-polymerizable acidic monomers with amide or ether linkages have been developed.