Background: Extensive mesio occluso distal cavities reduce cuspal stiffness and increase the risk of fracture. Short fiber reinforced composite may improve crack resistance, while semi direct fabrication may reduce polymerization stress. Aim: To compare fracture resistance and failure patterns among direct and semi direct restorations prepared with and without a short fiber reinforced composite substructure. Materials and Methods: Twenty-two extracted intact mandibular molars received standardized Class II MOD preparations and were allocated to direct SFRC (G1, n=8), direct conventional composite (G1C, n=3), semi direct SFRC (G2, n=8), or semi direct conventional composite (G2C, n=3). Restored specimens underwent axial compressive loading in a universal testing machine until fracture. One-way analysis of variance and Tukey HSD tests were applied at alpha=0.05. Results: Mean fracture resistance was 635.0 ± 33.73 N for G1, 580.0 ± 20.58 N for G1C, 761.0 ± 35.60 N for G2, and 623.0 ± 16.09 N for G2C. The overall group effect was significant (F(3,18)=35.25, P<0.001). G2 exceeded G1, G1C, and G2C (all Tukey adjusted P<0.001), whereas G1 did not differ significantly from G1C or G2C. Semi direct SFRC specimens showed a more favorable, repairable fracture pattern on descriptive assessment. Conclusion: Within the limits of this in vitro study, semi direct SFRC restorations produced the highest fracture resistance. The findings support further fatigue and clinical evaluation before routine clinical recommendations are made.