Dental adhesives can alter the contractility of vascular tissue via different mechanisms. The aim of this study was to investigate and compare the vascular action of two self-etch adhesive systems, Clearfil SE Bond (CSEB) and Clearfil S(3) Bond (CS3B). Responses of isolated rat thoracic aorta rings were recorded isometrically by force displacement transducers. Following pre-contraction of aorta rings, relaxations to the independent and mixed components of CSEB and CS3B were recorded in the absence and presence of nitric oxide synthase (NOS) inhibitor (N(omega)-nitro-L-arginine methyl ester (N-LAME)), cyclooxygenase (COX) inhibitor (indomethacin) and K+ channel inhibitors (tetraethylammonium, glibenclamide and 4-aminopyridine). We also tested the effects of CSEB and CS3B in endothelium-intact and -denuded rat thoracic aorta rings. To investigate the Ca2+-channel antagonistic effect of adhesive components, concentration-response curves to CaCl2 were obtained in the absence and presence of the components. The primer, the bond, and the mixture of CSEB and CS3B elicited concentration-dependent relaxations. Mechanical rubbing of the endothelium did not significantly modify the extent of vasorelaxation induced by the test materials. The vasorelaxant effect was mediated neither by NOS and COX inhibition nor by the tested K+ channel antagonists. Mechanical removal of the endothelium did not alter the vasodilatory effect induced by the self-etch adhesives. Both CSEB and CS3B significantly inhibited the contractions induced by CaCl2. These results demonstrate the vasodilatory effect induced by the self-etch adhesive systems through a Ca2+-antagonistic effect.