Purpose: To examine the stress values of different bone densities and to compare the tapered and cylindrical implant designs. Materials and Methods: Finite element analysis was used to apply a force of 100 N vertically and at an angle of 30 degrees to implants with a cylindrical or tapered design in D1 and D4 bones in eight separate models. The von Mises and principal stress values obtained from the models were compared, and the optimal stress values were determined and compared with the physiologic stress limit of the bone. Results: Von Mises stress was found to be lower in D1 bone densities, in vertical loading, and in implants with a tapered design. In the case of both implant designs, the von Mises and principal stress values were lower for D1 bone densities. The tapered implant was found to have higher principal stress than the cylindrical implant in both bone densities, while von Mises stress was higher in the cylindrical implant than in the tapered implant. Vertical loading was found to induce less stress than loading at a 30-degree angle. Conclusion: D4 bone density and loading at a 30-degree angle increases von Mises and principal stress more than selection of different implant designs. Keywords: bone density, cylindrical implant, finite element analysis, mandible, tapered implant