Prevalence, Risk Factors, and Outcomes of Radiographically Detected Void Formation Following Lateral Sinus Floor Elevation: A Retrospective Study

Objectives To investigate the prevalence, risk factors, and impact of void formation within graft materials following lateral sinus floor elevation (LSFE) on long‐term implant survival. Materials and Methods This retrospective study analyzed 307 patients who underwent LSFE between 2018 and 2023. Voids were identified on 6‐month postoperative cone‐beam computed tomography (CBCT), and patient‐, anatomical‐, and surgery‐related variables were assessed. Least Absolute Shrinkage and Selection Operator (LASSO) regression and multivariable logistic regression were used to identify independent risk factors. Implant survival in void versus non‐void groups was compared using Kaplan–Meier analysis and the log‐rank test. Results Voids were detected in 31.3% of cases (96/307). Three independent risk factors were identified: a specific graft material (OR = 4.02, 95% CI: 1.73–9.33, p = 0.001), increased graft amount (OR = 2.20, 95% CI: 1.20–4.01, p = 0.011), and a smaller sinus mucosa tension angle (SMTA; OR = 0.98, 95% CI: 0.96–1.00, p = 0.027). In a sensitivity analysis confined to conventional graft materials, graft material amount remained robust (OR = 2.02, p = 0.025), with Stage III periodontitis, multiple‐tooth units, and endo‐sinus bone gain additionally identified, whereas membrane perforation was unexpectedly protective (OR = 0.30, p = 0.049). Over a mean 46.6‐month follow‐up, voids were significantly associated with a higher implant failure rate (7.3% vs. 1.9%) and reduced cumulative survival ( p = 0.014). Conclusions Radiographically detected voids following LSFE are associated with increased implant failure and lower cumulative survival. Void formation was independently associated with graft composition, graft material amount, and SMTA; the association with graft material amount persisted after excluding one specific material. Membrane perforation showed an unexpected protective association requiring prospective validation.