EFFECTS OF N-METHACRYLOYL-OMEGA-AMINO ACID PRIMER PRETREATMENT ON THEBOND STRENGTH OF THE RESIN TO ACID-ETCHED DENTIN

To ascertain the adhesion mechanism of resins to etched dentin treated with hydrophilic primers such as N-methacryloyl-omega-amino acids (NM omega A), the effect of the application of NM omega A primers on the bond strength of the resin and also the characteristics of the ''hybri d layer'' were investigated. Here, the concept of ''hybrid layer'' has been proposed previously by Nakabayashi et al. When the demineralized dentin was treated with the NM omega A solution, the bond strength in creased remarkably, thus indicating the formation of a hybrid layer. I t can be construed that NM omega A primers allowed for diffusion of th e bonding agent to the dentinal collageous layer that was exposed by a cid etching, and thereby the creation of a hybrid layer. To obtain an understanding of how NM omega A primers improved bond strength at the interface between the resin and dentinal collagen, the C-13-NMR spectr a of NM alpha A were observed in the absence and presence of demineral ized dentin. The C-13 peak intensities of all of the carbons of Me NM alpha A species were dramatically reduced in Me presence of the dentin . Specifically, the reduction of the carbon peak intensity of carboxyl ic acid in the NM alpha A species was reduced by 30%. This indicated t hat the unionized carobxylic acid in the NM alpha A primer interacted with the dentinal collagen. Thus, the composite resin can be considere d to adhere to the dentinal collagen through the unionized NM alpha A that interacts with the dentinal collagen. (C) 1997 John Wiley & Sons, Inc.