Residual bone height and implant survival after lateral sinus floor elevation: a continuous-variable analysis with 14-year follow-up

Abstract Objectives: To evaluate the effect of residual bone height (RBH) on implant survival following lateral sinus floor elevation (LSFE), and to assess the influence of sinus membrane perforation and patient-related factors. Materials and Methods A total of 217 implants placed after LSFE were retrospectively analyzed. RBH was assessed both categorically (RBH < 2 mm, 2 ≤ RBH < 4 mm, RBH ≥ 4 mm) and as a continuous variable. Implant failure was the primary outcome. Associations were evaluated using chi-square tests, Kaplan–Meier survival analysis with log-rank testing, and Cox proportional hazards regression. Multivariable logistic regression was used to identify independent predictors, including sinus membrane perforation, smoking, age, and sex. Results: The overall implant failure rate was 8.8% (19/217). RBH was not significantly associated with implant loss when analyzed categorically (p > 0.05), and no significant differences in survival were observed among RBH groups (log-rank p = 0.258). However, when analyzed as a continuous variable, RBH showed a significant inverse association with implant failure, with each 1-mm increase reducing the odds of failure (OR = 0.62, 95% CI: 0.38–0.99, p = 0.045). Sinus membrane perforation was strongly associated with implant loss, with failure rates of 44.4% in perforated cases versus 5.5% in non-perforated cases (p < 0.001). Smoking showed a non-significant trend toward increased risk, while age and sex were not significantly associated with implant failure. Conclusions: RBH does not appear to be a significant predictor of implant loss when categorized; however, continuous analysis suggests a dose–response relationship, indicating that decreasing RBH progressively increases failure risk. Sinus membrane perforation emerged as the strongest determinant of implant failure, highlighting the critical importance of surgical technique in LSFE procedures.