Purpose: The aim of this study was to evaluate the volumetric stability of deproteinized bovine bone after sinus augmentation, using cone beam computed tomography (CBCT) and three-dimensional (3D) analysis. Materials and Methods: Using a specific selection tool and 3D reconstruction from InVesalius 3.0, volumetric analysis of CBCT scans was performed in patients undergoing a sinus elevation technique in critical defects, using deproteinized bovine bone. The first scan was performed immediately after graft surgery (T1), and the second was performed 8 months after graft surgery (T2). Results: A total of 13 patients met the inclusion criteria of this retrospective study; 26 postoperative CBCT scans were analyzed for these patients. All patients exhibited an increase in bone volume (9.10%). The mean bone volume increase from T1 to T2 was 0.137 cm3 (SD: ± 0.104 cm3). There was a statistically significant correlation between bone volume and time (P .0001). The mean bone volume was 1.506 cm3 (SD: ± 0.473 cm3) for T1 and 1.644 cm3 (SD: ± 0.506 cm3) for T2. Conclusion: Within the limited sample, the study demonstrated an increase in graft volume after sinus elevation with deproteinized bovine bone in critical defects. Keywords: Bio-Oss, bone grafting, cone beam CT scan, dental implants, maxillary sinus