Effect of Intrasinus Osteotome Sinus Floor Elevation Combined with Guided Bone Regeneration on Implant Survival Rate and Complications in Patients with Insufficient Vertical Bone Height: A Retrospective Cohort Study

Objective To investigate the association between implant placement timing in osteotome sinus floor elevation (OSFE) combined with guided bone regeneration (GBR) and implant survival, marginal bone loss (MBL), and postoperative complications in patients with insufficient vertical bone height.Methods This single-center retrospective cohort included 196 patients receiving 353 implants treated with OSFE+GBR from October 2019 to October 2022. Implants were placed simultaneously (S-implant) or ≥12 weeks after OSFE (D-implant). Outcomes included 3-year implant survival, early/late biological complications, and longitudinal MBL. Kaplan–Meier/Log-rank tests, multivariable logistic regression (cluster-robust by patient), and linear mixed-effects models were applied.Results The incidence of late complications was higher in the D-implant group than in the S-implant group (15.4% vs. 7.2%, p = 0.027). Schneiderian membrane perforation (OR = 3.372) and smoking (OR = 2.559) were independent risk factors for complications. LMM analysis showed a significant effect of time (β = 0.563) and a time–group interaction (β = −0.168). Smoking, diabetes, osteoporosis, and a history of sinusitis were associated with increased MBL.Conclusion Both simultaneous and delayed implant placement after OSFE with GBR achieved high implant survival, but showed different temporal patterns of marginal bone changes.