This in vitro study evaluated short-fiber-reinforced composite materials and fiber-reinforced restorations of endodontically treated molars with furcal perforation. The endodontic treatment and mesio-occlusal-distal cavity preparation of 126 two-rooted mandibular third molars were performed. Eighteen non-perforated teeth were restored with resin composite as the control group. Furcal perforations and repair were performed on 108 teeth that were divided into six experimental groups: resin composite (RC), everX Flow (EXF), everX Posterior (EXP), Bioblock (BB), modified transfixed (MT), and horizontal glass-fiber (HGF) groups (n = 18). Fracture resistance tests were performed at an angle of 30◦ using a universal testing machine under static loading, and fracture patterns were classified. Welch's analysis of variance, Pearson chi-square, and Tamhane post hoc tests (