Clinical Outcomes and Prognostic Factors Following Surgical Treatment for Peri-Implantitis: A Retrospective Cohort Study with 6- to 114-Month Follow-up.

OBJECTIVES: To evaluate implant survival and radiographic bone level outcomes after surgical treatment for peri-implantitis, and to identify factors associated with treatment outcomes. MATERIALS AND METHODS: This retrospective cohort study included patients who underwent surgical treatment for peri-implantitis at a university-affiliated hospital. between January 2000 and December 2024, with a minimum follow-up of 6 months. Patient-related variables, implant and prosthetic characteristics, surgical procedures, and follow-up records were collected. Radiographic measurements were used to assess changes in marginal bone levels. Implant survival and associated factors were evaluated using Kaplan-Meier survival analysis and Cox proportional hazards regression models. In addition, a generalized linear mixed model (GLMM) was applied to identify factors associated with postoperative radiographic bone level changes. RESULTS: A total of 57 patients (91 implants) were included in the study. The median follow-up period was 33 months. The overall implant survival rate after surgical treatment was 75.8% (69/91), and the median survival time was 87.0 months, exceeding 7 years. Twenty-two implants were removed at a mean of 37.1 months after treatment. Among the 69 surviving implants, the mean changes in mesial and distal marginal bone levels during follow-up were -0.54 ± 2.01 mm and -0.57 ± 1.81 mm, respectively. Additionally, preoperative bone loss emerged as a predictor of implant survival (p = 0.001). Regenerative surgical therapy was associated with significantly more favorable radiographic bone level outcomes compared with non-regenerative surgical approaches (p = 0.049). CONCLUSIONS: Preoperative bone loss was identified as an independent prognostic factor for implant survival after peri-implantitis surgery. Regenerative surgical therapy was associated with more favorable radiographic bone level outcomes than non-regenerative approaches following peri-implantitis treatment. However, longer postoperative follow-up was associated with an increased risk of further bone loss, highlighting the challenges of long-term disease control. CLINICAL SIGNIFICANCE: Surgical therapy for peri-implantitis may provide acceptable mid- to long-term implant survival; however, maintaining long-term disease control remains challenging. Greater preoperative bone loss was associated with an increased risk of implant loss, highlighting the importance of early intervention and risk stratification. Regenerative procedures may improve radiographic bone level outcomes in selected cases.