The purpose of this study was to develop a detailed 3- Dimension mandibular model with dental implants on the basis of CT data and to conduct stress analysis to characterize the effects of the material type of prosthesis on stress/strain distribution in the mandibular bone. Three types of materials, a polymer and two metals, with different elastic properties were chosen as the prosthesis materials. The analytical results showed that the Mises equivalent stress and equivalent elastic strain along the circumference of the implant at distal side were much higher than in the anterior region. It was also shown that the stress/strain concentration at the bone increased with decreasing the prosthesis stiffness. The stress/strain concentration observed in the circumference of the implants could be the driving force for loosening and fracture of the implants.