Long-Term Stability of Bone Graft After Implant Failure in Lateral Sinus Floor Elevation: A Retrospective Paired Study.

OBJECTIVES: This retrospective paired cohort study aimed to compare the three-dimensional volumetric shrinkage of endo-sinus bone graft between failed and surviving implants after one-stage lateral sinus floor elevation (LSFE), and to assess the feasibility of implant replacement without additional augmentation. MATERIALS AND METHODS: Twenty failed implants were matched 1:1 with 20 surviving implants based on key clinical variables. Cone-beam computed tomography scans at five time points were analyzed to quantify graft volume and height changes. Surgical methods and clinical outcomes for implant replacement were also recorded. Paired t-test and repeated measures ANOVA were used to compare the radiographic outcomes. RESULTS: The shrinkage rate of endo-sinus bone grafts was statistically comparable between failed and surviving implants (32.54% ± 20.68% vs. 21.93% ± 10.54% at 1-year follow-up, p > 0.05). Residual bone graft reached adequate height to support replaced implants. Most failed sites were successfully restored with direct implant replacement, and reinserted implants achieved a 90% survival rate over a mean follow-up of 45 months. CONCLUSIONS: The findings suggest that implant failure after LSFE does not necessarily correlate with accelerated resorption of bone graft, supporting the feasibility of direct implant replacement without further grafting.