Research progress on the effects of implant-supported overdentures on residual ridge remodelling in edentulous jaws: a narrative review

Residual ridge resorption (RRR) following tooth loss is a continuous and irreversible process that limits the effectiveness of conventional complete dentures and compromises masticatory function and quality of life. Implant-supported overdentures (implant overdentures [IODs]) can reconstruct physiological stress distribution, regulate inflammatory molecular signalling and optimise bone remodelling through combined biological and mechanical pathways, thereby helping to slow RRR. This review systematically summarises the biological mechanisms of RRR, including inflammatory mediators, the receptor activator of nuclear factor-kappa B ligand/osteoprotegerin pathway and systemic factors; the mechanical mechanisms, including Wolff's law and stress distribution patterns; the protective effects of IODs on residual ridges; key determinants of their bone-preserving efficacy, including implant-, attachment-, occlusion- and patient-related factors; current controversies; and advances in digital applications. Regarding attachment systems, current evidence from randomised controlled trials, long-term cohort studies and meta-analyses indicates that ball, Locator and bar attachments demonstrate broadly comparable peri-implant marginal bone outcomes, although Locator attachments may be associated with lower posterior RRR over 10 years, whereas bar attachments may offer superior crestal bone stability in specific clinical scenarios. No single attachment system demonstrates a clinically meaningful, reproducible advantage in bone preservation, and selection should be individualised based on anatomical, functional and maintenance considerations. Current evidence remains limited by heterogeneous study designs, variable follow-up periods and an overreliance on finite element analyses, underscoring the need for standardised long-term clinical trials with harmonised outcome measures. Evidence from recent high-quality studies over the past 5 years is integrated to propose stratified clinical recommendations according to bone volume, systemic status and economic factors. Digital technologies, including computer-guided surgery, digital impressions and occlusal analysis, further enhance precision and predictability of bone-preserving outcomes. This review provides a theoretical basis and clinical reference for optimising rehabilitation protocols, preserving residual ridges over the long term and improving prosthetic prognosis in patients with edentulism.