Effect of mandibular implant-supported prostheses on maxillary residual ridge resorption: A systematic review.
PURPOSE This systematic review evaluated the effect of mandibular implant-supported prosthetic design, including implant number, distribution, and attachment system, on maxillary residual ridge resorption (RRR) in completely edentulous patients. METHODS This systematic review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2020 guidelines. Electronic searches were performed in PubMed/MEDLINE, Scopus, Web of Science, and the Cochrane Library from inception to March 2026. Clinical studies evaluating maxillary RRR in patients rehabilitated with mandibular implant-supported overdentures (IODs) were included. Because of heterogeneity in study designs, prosthetic protocols, and outcome assessment methods, the findings were synthesized qualitatively. The certainty of evidence was assessed using Grading of Recommendations, Assessment, Development and Evaluation (GRADE). RESULTS Eighteen studies involving 496 edentulous participants were included, comprising randomized controlled trials, prospective clinical studies, and retrospective investigations with 1-10 years of follow-up. Mandibular treatments included 1-IODs, 2-IODs, 4-IODs, and implant-supported fixed dental prostheses. Maxillary RRR was generally comparable or reduced with mandibular IODs compared to conventional complete dentures. Resilient non-splinting attachments, particularly O-ring/stud, ball, locator, and magnet systems, were generally associated with less maxillary RRR than rigid splinting designs such as bar-clip and telescopic attachments. Implant number and distribution had limited influence, whereas anterior maxillary bone loss generally exceeded posterior loss. The certainty of evidence was low to moderate. CONCLUSIONS Mandibular IODs do not appear to substantially increase maxillary RRR compared with conventional dentures. Attachment design and occlusal loading may have greater influence on maxillary RRR patterns than implant number or distribution, although the certainty of evidence is low to moderate. Further multicenter trials with standardized CBCT-based outcomes are needed.