Ahmed Elawady D.M.Kaddah A.F.Talaat khalifa M.Faculty of Oral and Dental MedicineDepartment of Removable ProsthodonticsCairo UniversityEgypt; Faculty of DentistryDepartment of ProsthodonticsModern Science and ArtsUniversity (MSA)Egypt; Department of Removable ProsthodonticsCairo UniversityEgypt; Faculty of Oral and Dental MedicineDepartment of Removable Prosthodontics6th October UniversityEgypt2020-01-092020-01-09201715323382https://doi.org/10.1016/j.jebdp.2017.02.002PubMed ID : 28865818https://t.ly/P55yeScopusBackground As a consensus, the 2-implant supported overdentures (ODs) are considered as the first choice of treatment for the edentulous mandible. In the same context, there is increased evidence supporting the use of single-implant OD. The aim of any design is to preserve the remaining structures and allow the longevity of the treatment. Objectives To evaluate the impact of single implant vs 2 implants on the peri-implant marginal bone loss (MBL) and number of implant failures in mandibular implant overdentures. Methods A literature search of electronic databases (PubMed and Cochrane) was performed up to March 2016 and complemented by hand search. Randomized clinical trials (RCTs) that evaluated MBL and number of implant failures relative to single-implant mandibular overdenture (MOD) were selected. The review and meta-analysis were performed using meta-analytic statistical package and in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Findings Five RCTs met the inclusion criteria for systematic review and qualitative synthesis. The observation period ranged from 12 months to 5 years in the selected RCTs. The comparison included in the meta-analysis is single- vs 2-implant MODs. Pooled data revealed that single-implant MODs significantly decreased the MBL (mean difference: 0.27, 95% confidence interval: 0.20-0.34, P <.0001, I2 = 0%) and number of implant failures (risk ratio: 3.26, 95% confidence interval: 1.18-8.97), P =.02; I2 = 0%). Conclusions Single-implant MOD was found to be better than 2-implant MOD in terms of MBL and number of implant failures. However, this result should be interpreted with caution due to limited number of analyzed studies with different loading protocols and short follow-up period. � 2017 Elsevier Inc.EnglishDental implantMandibular prosthesisOverdentureSingle implantTwo implantsalveolar bone losshumanimplant-supported denturemandiblemeta analysisoverlay denturetooth implanttooth implantationAlveolar Bone LossDental Implantation, EndosseousDental ImplantsDental Prosthesis, Implant-SupportedDenture, OverlayHumansMandibleReviewhttps://doi.org/10.1016/j.jebdp.2017.02.002PubMed ID : 28865818