The Effect of Site Preparation and Timing on the Long-Term Survival of Dental Implants: A Multi-Center Retrospective Cohort Study

Abstract Purpose Alveolar ridge resorption following tooth extraction often necessitates bone augmentation. This study aimed to evaluate the long-term survival of dental implants placed with different site preparation procedures and timing protocols in a large, real-world patient cohort. Methods This retrospective cohort study utilized a multi-center electronic health record database to analyze 7,886 implants in 3,291 patients. Implants were categorized into seven cohorts: a control group (no augmentation) and groups for direct sinus augmentation, indirect sinus augmentation, and ridge preservation, with each procedure classified as either “simultaneous” with or “staged” relative to implant placement. The primary outcome was implant failure, defined as implant removal. Kaplan-Meier survival analysis and multivariable Cox proportional hazards regression were used to assess outcomes. Results All simultaneous augmentation procedures were associated with a significantly higher hazard of failure compared to the control group. Ridge preservation showed the highest risk, increasing the hazard of failure by 2.37 times when simultaneous and 1.81 times when staged. In contrast, staged sinus augmentation procedures did not show a statistically significant increase in failure risk. Diabetes and increasing age were also identified as significant patient-related risk factors. Conclusion In a real-world setting, simultaneous implant placement with bone augmentation is associated with a significantly higher risk of long-term failure. A staged approach, particularly for sinus augmentation, appears to be a safer and more predictable protocol.