Double-Window Technique For Lateral Approach Maxillary Sinus Floor Elevation

Maxillary posterior tooth loss can lead to resorption of the alveolar ridge and continuous pneumatization of the maxillary sinus, resulting in insufficient bone quantity in the maxillary posterior region. Studies have reported a 35.1% prevalence of maxillary sinus septa, with most septa located in the middle region (48.7%), which undoubtedly increases the difficulty of lateral approach sinus floor elevation. In this case, the residual bone height (RBH) was <3 mm, with the thinnest area measuring only 0.8 mm, and a sinus floor septum was present. The "double-window technique" was used for lateral window sinus augmentation, followed by delayed implantation, ultimately achieving successful prosthetic rehabilitation. In this case, the patient presented with severe alveolar ridge atrophy and a maxillary sinus septum, making conventional implant placement unfeasible. According to the ITI Consensus, when the residual bone height (RBH) is <3 mm, a lateral approach sinus floor elevation with delayed implantation is recommended. The surgeon utilized the "double-window technique" to avoid the sinus septum, which requires a certain level of technical sensitivity. Some studies suggest that preoperative digital window guides can be fabricated to locate the septum position and define the osteotomy window, thereby improving surgical accuracy and safety. In this case, postoperative follow-up showed favorable wound healing and successful functional loading of the implant, demonstrating that the double-window technique for lateral sinus floor elevation is a viable approach in cases with maxillary sinus septa.