For completely edentulous patients restored with implant retained prostheses, the following was concluded:1.Early loading could be as effective as delayed loading of implants regarding implant and prosthetic failures.2.Immediate loading was preferred than delayed loading regarding implant stability. However, regarding bone loss, immediate could be as effective as delayed loading protocol.3.The quality of evidence was assessedto be moderate to very low due to high and unclear risk of bias of the majority of the included studies and heterogeneity of some of the included articles.26.2 Implications for researchWe need further properly conducted RCTs, reporting implant and prosthetic failures, with calculated sample sizes and follow up periods more than 5 years. The following implications were also suggested: 1.These RCTs should be reported as recommended by the CONSORT statement (www.consort.org).2.Core implant and prosthetic failure outcomes should be set together with the COMET (Core Outcome Measures of Effectiveness Trial) initiavtives, while considering a universally accepted definition for the different loading protocols; immediate, early and delayed. This reduces the impact of a major source of variability between the studies. 3.Marginal bone loss should be measured by standardized intra-oral periapical digital radiographs. 4.If subgrouping was ever planned, it should be taken into consideration when calculating the sample size. 27. FundingThis review is totally self-funded and the authors declare no conflict of interests.