Influence of Cover Screw Loosening on Peri-implant Infection and Marginal Bone Loss: A Retrospective Observational Study

Background Cover screw-related infection is a potential early complication in two-stage dental implant procedures, potentially leading to peri-implant infection and marginal bone loss (MBL). This study aimed to assess the impact of such infections on early MBL and identify predictive factors. Methods This retrospective study included 194 implants placed via a submerged two-stage protocol. Patients were categorized into infection and control groups based on clinical presentation. Periapical radiographs at baseline, infection presentation, and after one year were analyzed to measure MBL. Data were statistically evaluated using descriptive analysis, Pearson correlation, and multiple linear regression. Results The infection group showed significantly higher MBL at presentation (1.97 ± 0.903 mm) and after one year (2.98 ± 1.115 mm) compared to the control group (0.378 ± 0.274 mm and 0.829 ± 0.503 mm, respectively; p < 0.0001). Infection, implant length, and MBL at presentation were identified as independent predictors of final MBL (R² = 0.965). Notably, each 1 mm increase in initial MBL led to an additional 1.177 mm loss over one year. Conclusion Cover screw-related infections significantly contribute to early MBL. Prompt detection and proper surgical technique are essential to reduce long-term bone loss and ensure implant success. Implant length and early bone changes are key predictive indicators for future MBL.