The aim of this retrospective study was to evaluate the long-term performance of the supercritical CO2 (Supercrit, BIOBank) viral-inactivated bone allografts in maxillary sinus augmentation. Thirty-four consecutive patients underwent 50 maxillary sinus augmentation procedures, and 103 implants were placed. At a mean of 8.8 years after graft surgery, 95 implants were well osseointegrated and functioning. Eight implants failed, and the overall implant survival rate at 10 years was 92.2%. The marginal bone loss averaged 1.2 ± 1.3 mm. Within the limitations of this study, the supercritical CO2 viral-inactivated bone allograft is a valuable bone graft material, achieving long-term satisfying outcomes when used alone.