This study aimed to compare the fracture resistance of composite core materials reinforced with varying fiber orientations. Composite cores of endodontically treated roots were prepared by reinforcing with woven fiber discs, fiber strips, or fiber chips, and their fracture resistance was compared to those with no reinforcement using a universal test machine (Instron, Lloyd Instruments). Reinforcement with fiber chips showed the highest fracture resistance and 50% retrievability, while no reinforcement showed the lowest fracture resistance with 62.5% retrievability. It can be concluded that the use of fiber chips may be an effective and practical method for reinforcement of the core material.