Clearfil DC Bond (DC) is a new single-step, dual-cure bonding agent. In this study, the shear bond strengths of a core build-up composite to dentin used with four bonding systems [DC, Unifil Core Self-Etching Bond (UC), Clearfil SE Bond (SE) and Cleafil tri-S Bond (TS)] were measured. The bonding ability after 7 days of storage and in vitro durability following 20,000 thermocycles were also evaluated. The bond strength of DC did not differ significantly from those of other bonding systems after 24 hours of storage. Another dual-cure bonding system, UC, showed a significant reduction of bond strength after 7 days of storage. On the other hand, the bond strength of TS, a light-cured bonding system with a similar composition to DC, was reduced significantly following 20,000 thermocycles. SE, a two-step light-cure bonding system in the same series as DC, provided superior bond strength under all conditions. Although DC showed a slightly lower bond strength than SE, there was no significant difference between DC and SE under all conditions. Consequently, DC may be a useful and effective bonding system for multiple composite resin restorations.