Retentive force of FRC posts inserted with core build-up composites and resin cements

The aim of this study was to determine the retentive forces of fiber-reinforced composite (FRC) posts luted with different core build-up composite resins, and resin cements. Extracted single-rooted teeth were restored using FRC posts luted with the core build-up composites Build-It, Culmat, Flow White, Luxacore, Multi-Core Flow, Rebilda DC and luted with the resin cements Calibra, Cement-It, Multilink, and RelyX Unicem (control group, no separate etching, priming or bonding steps). The Rebilda DC was used with both the light-polymerizing Solobond and the dual-polymerizing AdheSE. Following water storage (37°C, 24 h) and thermal cycling (5000 cycles, 5-55°C, 30 s) tensile strength testing was performed and fracture modes were assessed. Statistical analysis of the data was done by one-way ANOVA, Bonferroni/Dunn correction, and unpaired t-test with α = 0.05. Except for Multilink (319 N, SD 50 N) and Cement-It (331 N, SD 85 N) significantly higher retentive forces were obtained for the core build-up composite Build-It (422 N, SD 43 N) and for the resin cements Calibra (408 N, SD 50 N) and RelyX Unicem (405 N, SD 64 N) compared to the other materials (p < 0.001). The lowest retentive forces were found for the core build-up composites Luxacore (145 N, SD 36 N) and Rebilda DC/Solobond (148 N, SD 39 N) (p < 0.001). Fracture modes were mainly interfacial. The use of core build-up composites did not improve the retentive forces of FRC posts compared to resin cements. Except for Culmat, core build-up composites as well as resin cements in combination with dual-polymerizing bonding materials were superior to composites with light-polymerizing bonding materials.