A new adhesive-promoting monomer, 4-acryloxyethyltrimellitic acid (4-AET), was synthesized. The effects on the adhesion to bovine dentin and the polymerization reactivity [the inclusion varying from 0 to 10 wt % 4-AET of the experimental light-cured dental bonding resins (adhesive), wherein the adhesives were aged artificially at 50 degrees C over 2 weeks] were investigated, using tensile and sheer bond testing, a differential scanning calorimeter(DSC), and a scanning electron microscope (SEM). Tensile and shear bond strengths to ground dentin were not significantly decreased in 4-AET content over 2 weeks of aging, and the optimum concentration of 4-AET was found to be 5 wt %. The correlation between the tensile and shear bond strengths to the dentin was highly positive (r = 0.8517-0.9329) during the 2 weeks. The maximum temperature (T-max) of the polymerization in DSC was affected by the 4-AET content in the positive correlation. The correlation between the T-max and the bond strength to dentin was highly positive (r = 0.8995-0.9644). The SEM study showed that the bonding resin appeared to adhere strongly to ground dentin without the formation of resin-tags in the dentinal tubules. It was suggested that the bonding strength was attributable to the degree of penetration of the 4-AET/HEMA primer into the dentin and the polymerization reactivity of the bonding resin comprising 4-AET.