Effect of 4-Acryloxyethyltrimellitic Acid in a Self-etching Primer on Bonding to Ground Dentin

Abstract

To develop a self-etching primer for ground dentin, 4-acryloxyethyltrimellitic acid (4-AET) was newly synthesized, and the effect of concentrations varying from 0 (control) to 56.5wt% 4-AET in the water/HEMA primer on bonding to the dentin was investigated. Bond strength to the dentin was significantly affected by the inclusion of 4-AET in the primer which also contained N, N-di(hydroxyethyl)-p-toluidine (DEPT) when compared with the control (0% 4-AET) (p<0.01). The optimum 4-AET-concentration and the mean bond strength (SD) were found to be 6.5wt%: 24.2 (3.6)MPa, 37.4wt%: 25.3 (4.4)MPa, 47.2wt%: 26.9 (11.6)MPa and 54.4wt%: 29.7 (12.9)MPa. The role of DEPT in the 4-AET/HEMA primer was assessed, and the optimum DEPT-concentration was found to be 0.154 and 0.307mol%. Regarding the hypothetical bonding mechanism to dentin, it was thought that the ionized 4-AET in water/HEMA would penetrate into dentin substrates, and DEPT as an accelerator in situ would facilitate photo-polymerization at the dentin-resin interface, and result in increased bond strength to ground dentin.