Methods: The viscosity at 60 to 90 s after mixing two resin composite core materials used for luting fiber posts, Clearfil DC Core (DC) and Build-It FR (BI), was tested by a rheometer. Eighteen fiber posts (FibreKor) were divided into three groups which were surface-treated with one of the following treatments: 1) no surface treatment; 2) application of silane coupling agent (Silane); 3) application of silane followed by Bond-1 adhesive resin (Silane+Bond-1). Treated posts were cemented into artificial post spaces using DC or BI. After 24 h storage, each specimen was serially sliced into 12 beams for a microtensile bond strength test. The data were divided into upper, middle and bottom regions, and statistically analyzed (a = 0.05). Failure modes were observed using SEM.
Results: The viscosity of BI at 60 s after mixing was lower than that of DC. Bond strengths were found to be affected by luting resin composite, surface treatment, and region. For DC, bond strength was significantly improved in the group of Silane+Bond-1 (P <0.05). For BI, application of Silane significantly improved bond strength (P <0.05); but application of Silane+Bond-1 had no advantageous effect on bond strength.
Conclusions: Bond strengths between luting resin composites and fiber posts were affected by post surface treatments, depending on the resin composite used. Application of low-viscosity adhesive resin seemed to be beneficial for a high-viscosity luting resin composite.