The scope of this article is to review the current status of finite element analysis based studies on the matter of optimal dental implant length and diameter in the posterior mandible bone and discuss the findings in relation to 3D models used, materials used, type and magnitude of loading. The search of the literature was carried out using electronic databases PubMed, EbscoHost, as well as a manual search of finite element analysis based studies on dental implant diameter and length published between 2000 and 2018, using the terms: finite element analysis, dental implants, implant diameter an implant length. Current finite element analysis studies on the influence of diameter and length of implants present high variability due to the bone models used, material properties assigned, magnitude and type of loading, design of implants and dimensions investigated. However, a clear result is that the diameter of the implant has a great influence on crestal bone stress, an increase in the diameter leading to a decrease in stress. Increase in length leads to a decline in stress values in the bone tissue, but a clear consensus has not been reached yet concerning the extent of its influence on the cortical bone or cancellous bone.