Clinical Performance and Survival Outcomes of All-on-4 Full-Arch Implant-Supported Prostheses in Patients With a Completely Edentulous Arch: A Retrospective Cohort Study

Introduction: All-on-4 full-arch implant-supported prostheses have become a predictable treatment option for rehabilitating completely edentulous patients by providing improved function, esthetics, and patient satisfaction while minimizing the need for extensive bone grafting.However, long-term evidence regarding implant survival, prosthetic success, and biological and mechanical complications is essential for validating their clinical effectiveness.This study aimed to evaluate the clinical performance, survival outcomes, biological and mechanical complications, and marginal bone loss associated with All-on-4 full-arch implantsupported prostheses after a minimum follow-up of 24 months.Materials and methods: This retrospective observational cohort study included 90 completely edentulous arches (360 implants) rehabilitated with All-on-4 full-arch implant-supported prostheses between January 2013 and March 2019.Clinical, surgical, prosthetic, and radiographic records were reviewed.The primary outcomes included implant survival, implant success, and prosthesis survival.Secondary outcomes included marginal bone loss, peri-implant health, and biological and mechanical complications.Survival analysis was performed using the Kaplan-Meier estimates, and generalized estimating equations were used to evaluate the predictors of marginal bone loss.Statistical significance was set at p < 0.05.Results: The mean patient age was 58.4 ± 9.6 years.At 24 months, implant survival, implant success, and prosthesis survival rates were 96.7%, 93.3%, and 96.7%, respectively.Peri-implant mucositis was the most common biological complication, followed by screw loosening, occlusal wear, peri-implantitis, implant mobility, screw fracture, and framework and prosthesis fractures.Implant failure did not differ significantly according to arch location (p = 0.578) or the loading protocol (p = 0.092).Immediate loading demonstrated significantly lower marginal bone loss than delayed loading (0.54 ± 0.17 mm vs. 0.66 ± 0.21 mm; β = -0.118mm; 95% CI: -0.192 to -0.044; p = 0.002).Conclusion: All-on-4 full-arch implant-supported prostheses demonstrated excellent medium-term clinical performance, with high implant and prosthesis survival rates, minimal complications, and favorable marginal bone preservation rates.Immediate loading was associated with significantly lower marginal bone loss, supporting its use in appropriately selected patients.