In this study, we evaluated the antibacterial activity of self-etching adhesive systems against Streptococcus mutans using the agar diffusion method.

Three 2-step systems, Clearfil SE Bond (SE, Kuraray), Contax (CT, DMG), and Unifil Bond (UnB, GC), and three 1-step systems, Easy Bond (EB, 3M ESPE), U-Bond (UB, Vericom), and All Bond SE (AB, BISCO) were used. 0.12% chlorhexidine (CHX, Bukwang) and 37% phosphoric acid gel (PA, Vericom) were used as positive controls.

The antibacterial activity of CHX and PA was stronger than that of the other groups, except SE. After light activation, the inhibition zone was reduced in the case of all 2-step systems except CT. However, all 1-step systems did not exhibit any inhibition zone upon the light activation.

SE may be better than CT or UnB among the 2-step systems with respect to antibacterial activity, however, 1-step systems do not exhibit any antibacterial activity after light curing.