Purpose: The Target of this work was to study the effect of two different techniques of framework construction on the passive fit of screw-retained prostheses supported by six implants placed in the completely edentulous maxillae. The two techniques of screw retained framework construction were the following; The Conventional Cast Metal Technology and the Simultaneous Milling (CAD/CAM) Technology. Materials and Methods: In this study, a total of seventy-two implants were placed in twelve patients with completely edentulous maxillae. All selected patients were with normal maxillo-mandibular relationship, with no parafunctional habits and free of any systemic diseases. For each patient, six implants were placed in the lateral incisor/Canine region, first premolar and first molar region according to the available bone height and width. Bone height measurements around each implant was performed at zero, four and eight months after prostheses delivery to evaluate the changes that occurred in the supporting structures of implants placed in the maxilla as a result of two different techniques of framework construction; the conventional casting technique and the CAD/CAM technique. Results: After 4 months (p=0.002*) and 8 months (p=0.001*); the CAD/CAM group showed statistically significantly higher mean bone height measurements than the conventional casting group. There was a statistically significant decrease in mean bone height measurements after 4 (p=0.006*) and 8 (p=0.019*) months in the CAD/CAM group. Conclusion: CAD/CAM restorations yielded a more favourable bone reaction at the bone/implant interface than the Conventional Casting group throughout a short-term study period. Interest in the CAD/CAM technology for implant restorations is increasing because the frameworks and abutments may be machined from solid blanks of material that are more homogenous and with better physical properties than the conventional castings.