Efficacy of Self-etching Primer containing Water-soluble Monomers in the Adhesion of 4-META/MMA-TBB Resin to Bovine Ground Enamel

Abstract

We evaluated the efficacy of water-soluble monomers in the adhesion of 4-methacryloxyethyl trimellitate anhydride (4-META)/ methyl methacrylate (MMA)- tri-n-butyl borane (TBB) resin to enamel. An original self-etching primer containing an aqueous mixture of 4-methacryloxyethyl trimellitic acid (4-MET) and 35 wt% water-soluble monomers was designed. As water-soluble monomers, Glycerol dimethacrylate (GMR), Glycerol methacrylate acrylate (GAM) and 2,2-Bis(4-methacryloxy polyethoxyphenyl)propane (BPE) were used. Polished bovine enamel surfaces were treated with the self-etching primer for 30 s. The tensile bond strength of 4-META/MMA-TBB resin to enamel was measured after 1-day immersion in water at 37°C. The self-etching primer containing GMR or GAM produced comparable bond strengths with phosphoric acid etching. On the other hand, the bond strength by BPE self-etching primer was significantly lower than GMR and GAM self-etching primer and phosphoric acid etching. This was due to the difference in the viscosity of water-soluble monomers. BPE had higher viscosity than GMR and GAM. The observation by Field-emission scanning electron microscopy showed that the self-etching primer treatment showed less dissolution of enamel surface than phosphoric acid etching. In conclusion, the self-etching primer containing GMR or GAM may be an alternative to phosphoric acid etching for the adhesion of TBB-initiated 4-META/MMA resin cement to enamel, in spite of less dissolution of the enamel surface.