Maxillary sinus floor augmentation (also termed sinus lift, sinus graft, sinus augmentation or sinus procedure) is a surgical procedure which aims to increase the amount of bone in the posterior maxilla (upper jaw bone), in the area of the premolar and molar teeth, by lifting the lower Schneiderian membrane (sinus membrane) and placing a bone graft.
When a tooth is lost the alveolar process begins to remodel. The vacant tooth socket collapses as it heals leaving an edentulous (toothless) area, termed a ridge. This collapse causes a loss in both height and width of the surrounding bone. In addition, when a maxillary molar or premolar is lost, the floor of the maxillary sinus expands, which further diminishes the thickness of the underlying bone. Overall, this leads to a loss in volume of bone that is available for implantation of dental implants, which rely on osseointegration (bone integration), to replace missing teeth. The goal of the sinus lift is to graft extra bone into the maxillary sinus, so more bone is available to support a dental implant.