Objective: The objective of this review is to evaluate maxillary and mandibular all-on-four implant designs, their indications and contraindications, advantages and disadvantages. Methods: By using Pubmed, Cochrane Library, and Google Scholar, data from January 2003 to February 2018 were scanned electronically and manually as the title, abstract, and full text. The keywords specified were determined to be the all-on-four concept, full-arch implant prostheses, 4-implant full-arch, and tilted implants. The inclusion criteria consisted of the all-on-four implant design, its use in completely edentulous maxillary and mandibular cases, advantages and disadvantages of the technique, and changes observed in the maxilla and mandible in completely edentulous cases. Clinical trials and laboratory studies on the subject using the full text and English language were evaluated. Results: A total of 176 articles were found as a result of Google Scholar, Pubmed, and Cochrane Library. Thirty-seven articles were selected according to inclusion criteria; of these, 20 were related to the clinical trials. In addition, a total of 13 articles were found as a result of an additional hand search by screening the reference list of all included publications; of these, 11 was related to the clinical trials. Conclusions: It is necessary to carry out longer-term clinical and laboratory studies to determine long-term success criteria in all-on-four implant designs and to use new ceramic systems.