The objective of this study was to assess the flexural and shear strengths of a denture base resin composed of Poly-Methyl-Methacrylate (PMMA) that had undergone milling using Computer-Aided Design/Computer-Aided Manufacturing (CAD/CAM) and repair using acrylic resins that had been heat-, auto-, and light-polymerized subsequent to a range of chemical and mechanical surface treatments. Material and Methods: 285 CAD/CAM milled resin specimens with rectangular shapes were created. A total of 15 specimens were preserved as controls, and the remaining 270 specimens underwent 3 mm-wide repairs. With resins that were heat-polymerized, auto-polymerized, and/or light-polymerized, the specimens from three groups (n = 90) were repaired, respectively. According to the method of surface treatment (MMA monomer, sandblasting roughened, and combination), the specimens of each primary repair resin were further separated into 3 subdivisions (n=30). The specimens underwent three-point flexural and shear bond strength tests (n=15). The one-way ANOVA test was used to analyze the maximum load required to fracture the specimens statistically. Results: For CAD/CAM repair, the heat-polymerized PMMA resin produced a much stronger bond than the auto-polymerized and light-polymerized resins. Roughening plus MMA monomer produced a significantly stronger link than MMA monomer alone or MMA monomer plus roughening alone. Conclusions: The use of heat-polymerized PMMA resin is recommended for CAD/CAM resin repair in combination with MMA monomer and roughening