Factors influencing long-term survival rates of implants placed simultaneously with lateral maxillary sinus floor augmentation: A 6-to 20-year retrospective study

Objectives To evaluate the long-term influence of residual bone height (RBH), sinus membrane perforation and the presence of voids on the survival of implants placed simultaneously with lateral maxillary sinus floor augmentation (MSFA). Materials and Methods A total of 207 patients (613 implants) who underwent MSFA from 1999 to 2003 and followed up until 2018 were included in this study. RBH and marginal bone loss were assessed using a series of panoramic and periapical radiographs. Cumulative survival rates (CSR) with log-rank tests and hazard ratios of implant failure according to RBH, membrane perforation, and the presence of voids were assessed. Results The overall 10-year and 20-year CSRs were 95% (95% CI: 84.95%-85.05%) and 85% (95% CI: 84.95%-85.05%), respectively. CSR was significantly higher for implants with >= 3 mm RBH (n = 260, 92.4%) than those with <3 mm RBH (n = 353, 78.8%) (p = .002). CSR of non-smoking group (n = 312, 90.0%) was higher than that of smoking group (n = 301, 77.1%) (p = .009). There was no significant difference in the hazard ratio of implant failure between the perforated membrane group (n = 245) and the non-perforated group (n = 368). In two out of 11 patients with voids, the inflammation of peri-implantitis progressed into voids, resulting in severe bone resorption. Conclusions The survival of implants placed in <3 mm of RBH, even though it showed a lower CSR, could be considered acceptable. Neither sinus membrane perforation nor the presence of voids appeared to affect implant survival as long as supportive maintenance therapy with proper oral hygiene was provided.