Purpose: The purpose of this study was to evaluate the fracture resistance of 5 different all-ceramic crown systems (In-Ceram, Empres staining technique, Empress veneering technique, Celay feldspathic system, and Celay In-Ceram system) before and after cyclic preloading in an artificial mouth. Materials and Methods: Extracted natural maxillary incisors we re prepared with a 90-degree shoulder. The crowns were adhesively luted to the abtuments using dual-cured composite cement. Half of the specimens were artificially aged via a chewing simulation and thermocycling, and all specimens were tested for fracture strength. The results were compared with those of porcelain-fused-to-metal (PFM) crowns with circular porcelain-butt margins that were cemented with zinc phosphate cement. Results: The chewing simulation and the thermocycling significantly decreased the fracture strength of all tested crown systems (P 0.01). There were no statistically significant differences between the all-ceramic crown groups and the PFM crowns. Conclusion: All-ceramic crowns can be used for anterior restorations. However, in vivo investigations of all-ceramic crown systems should be undertaken before introducing them into routine clinical use.