Sinus Bone Graft Stability and Implant Survival Following Transalveolar Sinus Floor Elevation in Severely Atrophic Maxilla: A Retrospective Study With 5-8 Years of Follow-Up.

Objectives: To evaluate the clinical and radiographic results of transalveolar sinus floor elevation (TSFE) with grafting in cases of severely atrophic maxilla.

Materials and methods: A retrospective analysis of clinical and radiographic data was conducted. Between 2015 and 2018, a total of 105 implants were placed in 105 patients over a follow-up period of 5-8 years. Implant failures and endo-sinus bone gain (ESBG) were assessed. Statistical models were established to investigate the potential influencing factors of implant survival and ESBG.

Results: Six patients with six implants were lost, resulting in cumulative survival rates of 94% for both patient- and implant-based analyses. The 8-year cumulative survival rate was significantly lower for residual bone height (RBH) < 4 mm (88%) compared to RBH 4-6 mm (98%). ESBG ≥ 4 mm and ESBG ≥ 6 mm were observed in 89.90% and 58.59% of implant sites, respectively. According to the log-rank Mantel-Cox analysis results, none of the factors examined were significantly related to implant failure, except for RBH (p = 0.038) at baseline. The linear mixed-model regression results showed that the final ESBG was positively correlated with implant insertion site (p = 0.003), implant length (p < 0.001), sinus floor elevation (SFE) methods (p = 0.010), and RBH (p < 0.001).

Conclusions: Within the limitations of this study, it has been established that TSFE with grafting was a reliable method for implant placement in the posterior atrophic maxilla ridges with RBH ranging from 4 to 6 mm. Nevertheless, caution was advised when considering its application in cases where the initial bone height falls below 4 mm.