This study investigated the load bearing capacity of intraradicular posts and core materials under static and dynamic loading. Human teeth with single root (N = 154, n = 14 per sub group) were endodontically prepared and randomly divided into six groups: CON: Sound premolars; TP: Titanium post (Flat Head T); FRCP: Indirect E-glass FRC post (FRC Postec Plus); FRCC: Fiber-reinforced resin composite (Everex Posterior) as post and core; RCW: Hybrid composite (Tetric) as post and core with woven fiber network (EverNet) between root canal and core; RC: Hybrid composite (Tetric) as post and core material. Groups TP, FRCP were luted adhesively in the root canal (Panavia 21), while other groups were bonded directly to the intraradicular dentin. In groups TP, FRCP, RCW, core material was hybrid composite. The teeth were then restored with CAD/CAM resin composite (ArtBlock Temp). While half of the specimens in each group were fractured after 4 weeks water storage, the other half was subjected to chewing simulation (x1.200.000; 5–55 °C). Data for Finitial (N) and Fmax (N) were analyzed using 2-way ANOVA and Tukey’s tests (alpha = 0.05). Fracture strength values were significantly affected by the post and core type (p < 0.05) and the fatigue conditions (p < 0.05). After cyclic loading, Finitial values were significantly lower for TP (222.70) and RCW (238.60), compared to other groups (335.50 − 377.20) (p < 0.05) and Fmax was significantly lower for RCW (742.11). TP group presented mainly cohesive failure in the crown material with adhesive detachment from the post core and other groups showed predominantly irreparable failures.