Extent of cement polymerization along dowel space as a function of the interaction between adhesive and cement in fiber post cementation

Purpose: To assess whether the polymerization extent of cement is influenced by curing mode of the adhesive and/or by photoactivation of the cement. Materials and Methods: One hundred five root segments were prepared from endodontically treated teeth. After post space preparation, the root segments were randomly divided into 7 groups, based on the cementation procedure to lute RelyX Fiber Posts (3M ESPE): 1. Variolink II (V, Ivoclar Vivadent); 2. V light-cured (LC); 3. Excite LC (ELC, Ivoclar Vivadent)/V; 4. ELC/V LC; 5. ELC-V LC (One Shot); 6. Excite DSC (EDSC)/V; 7. EDSC-V LC (One Shot). Each root segment was submitted to the acetone shake test to remove the unpolymerized resin and then cut longitudinally. On each half, the extent of cure of the cement was measured with image analysis software. 

Results: The deepest and basically complete polymerization was obtained with EDSC (groups 6 and 7), regardless of whether light curing was performed. The extent of polymerization was most limited when adhesive was not applied (groups 1 and 2), or when ELC was only light cured, while V was allowed to auto-cure (group 3). With the one-shot polymerization of ELC and V (group 5), the extent of polymerization was similar to the procedure involving separate irradiation of adhesive and cement (group 4). The one-shot technique was significantly more effective if EDSC was used (group 6). 

Conclusion: The use of a self-activating dual-curing adhesive system in combination with a dual-curing cement enables effective luting of FRC posts regardless of the amount of light transmitted through the post.