Survival, Biological, Prosthetic, and Patient-Reported Outcomes oF Attachment Systems in Implant-Supported Overdentures: A Systematic Review

Abstract

Background
Implant-supported overdentures (ISODs) have become the preferred treatment option for completely edentulous patients requiring improved denture retention, stability, and function. Various attachment systems, including ball, bar, Locator, magnetic, telescopic, and other low-profile attachments, have been introduced to optimize prosthesis retention and patient satisfaction. Despite numerous clinical investigations, consensus regarding the superiority of one attachment system over another remains inconclusive because of differences in study design, follow-up duration, outcome measures, and maintenance requirements.
Objective
To systematically evaluate and compare the clinical performance of different attachment systems used for implant-supported overdentures with respect to implant survival, biological outcomes, prosthetic complications, maintenance requirements, and patient-reported outcomes.
Materials and Methods
A systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA 2020) guidelines and prospectively registered in the International Prospective Register of Systematic Reviews (PROSPERO; CRD420261419351). Electronic searches of PubMed/MEDLINE, Scopus, Web of Science, Embase, and the Cochrane Central Register of Controlled Trials were performed. Randomized controlled trials, prospective and retrospective comparative clinical studies, and longitudinal cohort studies evaluating different attachment systems for implant-supported overdentures were included. Two independent reviewers performed study selection, data extraction, and quality assessment. The risk of bias was assessed using the Cochrane Risk of Bias 2 (RoB 2) tool for randomized controlled trials and the ROBINS-I tool for non-randomized studies. Owing to substantial methodological heterogeneity, findings were synthesized narratively.
Results
Eighteen comparative clinical studies fulfilled the eligibility criteria. Implant survival exceeded 95% irrespective of attachment type. Marginal bone loss and peri-implant soft tissue health were generally comparable among bar, ball, and Locator attachments. Prosthetic maintenance represented the principal difference between attachment systems, with Locator attachments requiring periodic replacement of nylon inserts, ball attachments requiring matrix replacement, and bar attachments necessitating occasional clip activation and laboratory maintenance. Although bar attachments demonstrated superior retention, Locator attachments offered favorable ease of use and reduced vertical restorative space requirements. Patient satisfaction improved significantly with all attachment systems, with no consistent evidence supporting the superiority of any single attachment design.
Conclusions
Current evidence indicates that implant survival and biological outcomes are largely independent of attachment design. Differences among attachment systems primarily relate to prosthetic maintenance, cost, restorative space requirements, and patient-specific clinical considerations. Selection of attachment systems should therefore be individualized according to anatomical, functional, prosthetic, and maintenance-related factors rather than implant survival alone.