RESUMEN
AIM: This study aimed to investigate the influence of using dual-cure composite core materials for fiber post luting on the fracture resistance of endodontically treated maxillary central incisors. MATERIALS AND METHODS: Fifty sound and recently extracted maxillary central incisors were endodontically treated and distributed into five groups. In the control group, access cavities were restored with the composite resin. Experimental groups had the coronal structure trimmed 2 mm above the cementoenamel junction. Teeth were restored with fiber posts and different combinations of luting and core materials: RelyX Unicem for post luting and MultiCore for core buildup; MultiCore for post luting and core buildup; RelyX Unicem for post luting and LuxaCore for core buildup; or LuxaCore for post luting and core buildup. All teeth were restored with zirconium crowns and subjected to thermocycling (6000 cycles 5/55°C). Loading of the teeth was applied at 135° to the palatal surface, using a universal testing machine at a cross-speed of 0.5 mm/minute until failure. The mode of failure was analyzed under a digital microscope. RESULTS: The fracture resistance of the control group was significantly higher than the experimental groups (p < 0.05). There was no significant difference between the experimental groups (p > 0.05). All teeth demonstrated nonrestorable failures. CONCLUSION: With the presence of the ferrule effect and crown restoration, the selected materials for post luting and core buildup have no significant influence on the fracture resistance of the endodontically treated teeth. CLINICAL SIGNIFICANCE: The use of the same dual-cure composite core materials for fiber post luting and core buildup would simplify the clinical procedure without enhancement of the fracture resistance of the endodontically treated tooth.