INTRODUCTION: The goal of modern dentistry is to restore the patient to normal contour, function and esthetics. And what makes implant dentistry unique is the ability to achieve this goal regardless of the atrophy, disease or injury. Implants with small diameters can be used successfully in a variety of clinical situations. A main drawback of Narrow-diameter implants is the possibility of not reaching the required primary stability (> 35Ncm). In such cases, being a one-piece implant, occlusal stresses are expected to disturb proper osseointegration. Lately, 2-piece narrow diameter implants were introduced to the market combining the undisturbed healing period required for proper osseointegration and the avoidance of extensive surgeries for bone augmentation. OBJECTIVES The purpose of this study is to determine, using 3-dimensional finite element analysis, whether 1-piece and 2-piece narrow diameter implants with equivalent geometries exhibit stresses and strains differently under applied loading conditions when used to retain a mandibular overdenture and, to evaluate how stresses are transmitted to the surrounding bone. MATERIALS AND METHODS: A computer based numerical model is structured for the anterior segment of the mandible with, 2 narrow diameter implants retaining a mandibular overdenture, one being a 1-piece and the other being a 2-piece. A 35N, and a 100N loads were applied through the overdenture, and Von Mises stresses were analyzed along the implants and the surrounding bone. RESULTS Stresses around the 2-piece design were greater than those around the 1-piece design, but the values recorded were still below the yield strength of implants and bone. CONCLUSIONS: A 2-piece narrow diameter implant can be a reliable treatment option to retain overdentures in cases where immediate loading is not recommended