Purpose: To verify whether lateral sinus floor elevation (LSFE) with the vertical height of the osteotomy decreased to 3 to 5 mm can achieve improvement compared with a conventional lateral window in terms of implant survival, graft stability, and related complications. Materials and Methods: Of the 49 patients who were selected for inclusion in this retrospective study, 25 patients were in the test group and 24 were in the control group based on the vertical height of the lateral window. Each patient received the LSFE treatment using deproteinized bovine bone mineral (DBBM) based on the two different vertical heights of the lateral window (test group: 3 to 5 mm; control group: 6 to 8 mm in vertical height). Residual bone dimensions were measured preoperatively, and graft dimensions were measured immediately after the procedure (baseline), 6 months (T1), and 1 year (T2) postoperatively on the basis of cone beam computed tomography (CBCT) scans. CBCT scan data at the baseline were analyzed with image processing software to evaluate the volume of augmented material, and they were transformed into three-dimensional reconstruction images to calibrate the window dimension. Implant failure and recorded intraoperative and postoperative complications were counted. Results: A prominent augmented graft height was obtained in both groups (test group: 9.48 ± 3.27 mm; control group: 10.44 ± 3.01 mm) with no significant difference; likewise, no difference was observed concerning augmented graft volume. Neither cumulative survival rate (CSR) nor augmented graft height decrement had any statistical intergroup difference during each follow-up interval. CSRs were detected as 100% for the test group and 94.28% and 91.67% for the control group based on implants and patients, respectively. Intraoperative membrane perforation was reported in two cases with a few nosebleeds the first night in the test group, while one case occurred in the control group. All the perforations were successfully sealed intraoperatively by a collagen membrane. Conclusion: Osteotomy of LSFE with decreased vertical height yielded similar results to the control group with conventional dimensions in terms of implant survival, graft stability, and related complications with 1 year of follow-up. Notwithstanding, a prospective split-mouth randomized controlled trial with long-term observation is imperative to further investigate the influence of decreased vertical height of the lateral window on maturation and consolidation of DBBM. Schlagwörter: deproteinized bovine bone mineral, lateral window, maxillary sinus floor augmentation, osteotomy