Purpose: This clinical study evaluated the behavior of inlay fixed partial dentures (IFPD) with conventional and modified framework designs over a period of 12 to 48 months. Materials and Methods: Forty-one glass fiber-reinforced composite IFPDs were made to replace one missing maxillary or mandibular tooth. The frameworks were made only with parallel fibers in 19 restorations (group 1) and built with parallel and woven fibers modifying the design of the pontic element in 22 IFPDs (group 2) according to the manufacturer's instructions. All restorations were evaluated by color match, marginal discoloration, secondary caries, surface texture, marginal adaptation, fracture, and postoperative sensitivity. Results: Three partial adhesive-cohesive veneering composite fractures occurred in the pontic element in group 1 after 3, 4, and 8 months, respectively. One cohesive fracture occurred in an abutment in group 2 after 46 months. Group 1 showed a 16% fracture failure rate; group 2 showed a 5% failure rate. However, no statistical difference was detected between the groups. IFPDs received the highest score at the following rates: color match 71%, marginal discoloration 96%, secondary caries 99%, surface texture 88%, marginal adaptation 98%, fracture 90%, and postoperative sensitivity 100%. Statistical analysis indicated significant deterioration of color match from baseline to last recall. Conclusion: There were nonsignificantly fewer fractures of the veneering composite with the modified design of the framework than with the conventional design. Repair of the fractured veneer of IFPDs may lengthen the lifespan of the restorations, but it is advisable only for slight damage.