The extension of sinus floor augmentation beyond the edentulous area, apical to the adjacent teeth, has many therapeutic advantages, but the reliability and safety of the procedure has not been assessed in depth. The present study compares the gain of bone anterior and posterior to the edentulous area and evaluates potential advantages and limitations in the clinical setting. The maximum vertical bone height in the edentulous and extended maxillary sinus augmentation (EMSA) areas and the thickness of the sinus membrane of 65 patients were measured. Those measurements were analyzed using the t test and Pearson correlations. The average vertical bone gain was 11.98 ± 3.53 mm in the edentulous sinus area and 8.60 ± 3.89 mm in the EMSA area (P < .05). Minor perforations of the sinus membrane occurred in 4 patients. There were no postsurgical graft contaminations or periradicular changes during follow-up. EMSA is a reliable and safe procedure with a very low complication rate. This approach is effective and safe for patients who have lost part of their posterior dentition. It enables future implant placement while avoiding the need for sinus reentry and proximal teeth extraction.