Objectives: The aim of the study is to evaluate the effect of compression applied to the alveolar bone on the clinical success of simultaneous ridge expansion and implant placement in treatment of narrow mandibular alveolar ridges. Materials and Methods: the study was conducted on six healthy patients with horizontally deficient mandibular partially edentulous alveolar ridges. Alveolar ridge expansion done manually by threaded bone expanders followed by installation of self tapping implant fixture. All the implants were immediately loaded with non functional temporary acrylic restorations. Results: six implants out of seven implants installed were successfully osseointegrated, which gives rise to a cumulative success rate of 85.7%. The Statistical analysis showed a significant increase in horizontal alveolar ridge dimensions immediately postoperative. Conclusion: Threaded bone expanders can be used effectively in expanding narrow mandibular edentulous ridges. Osseous pressure necrosis has not been noted from osseocompression and high insertion torque.