AIM This case series is aimed to report a new phenomenon, the "dome phenomenon," which was observed in infected augmented sinuses over several years. METHODS Five patients are presented in whom sinus lift augmentation resulted in postoperative infection with inflammation and suppuration. The patients received aggressive anti-inflammatory treatment and surgical debridement of the inflamed tissue, including some grafted material performed through the lateral window of the primary procedure. RESULTS The inflammatory condition was reversed, and the site healed clinically. Radiographically, a dome-shaped, radio-opaque tissue was observed at the superior most aspect of the grafted sinus. This "dome phenomenon" was further confirmed during dental implant placement, which indicates healing potential adjacent to the maxillary sinus membrane. CONCLUSIONS The current report, as well as other studies and case series, suggests that there is great potential for healing and bone formation in the maxillary sinus membrane. The precise mechanism is not known. Further clinical and histologic studies are needed to understand the regenerative potential of the Schneiderian membrane.