Maxillary sinus lift When a large maxillary sinus or a low maxillary sinus floor wall exists, or when the maxillary posterior teeth are missing due to alveolar bone resorption, maxillary sinus pneumatization, bone loss, etc., there is often a lack of vertical bone volume, which may penetrate the maxillary sinus wall once the implant is placed, and in order to place the implant, it is often necessary to transplant some synthetic bone substitute to elevate it to its original position, which will ensure that the implant In the maxilla, this procedure is called maxillary sinus lift. Depending on the surgical approach, there are open and closed procedures. Open – external maxillary sinus lift The external maxillary sinus lift (trans-lateral) is performed by opening a window in the lateral wall of the maxillary sinus, peeling the mucosa of the maxillary sinus floor under direct vision and pushing it upwards and inwards, with or without the implantation of (less elevated) bone graft material between the mucosa of the maxillary sinus floor and the maxillary sinus floor, in order to increase the amount of bone from the maxillary sinus floor to the top of the alveolar ridge. The decision to restore the implant in one stage can be based on whether the original bone height of the maxillary sinus floor can guarantee the initial stability of the implant, or if the bone volume is less, a second stage implant surgery is also feasible. This procedure is complex, relatively invasive and takes a long time. Closed – maxillary sinus lift The maxillary sinus lift (trans-alveolar crest) is used in cases where a single tooth or a spaced tooth is missing from the posterior maxilla. The implant socket is prepared at the top of the alveolar ridge and the bone tissue around the implant socket is compressed to increase the bone density. The implant socket is prepared with an annular drill and drilled close to the maxillary sinus floor. The bone material can then be inserted by gently tapping the columnar bone block obtained by preparing the implant socket and separating it from the mucosa of the maxillary sinus floor using an intrasinus lifting instrument. After pushing the mucosa of the maxillary sinus floor upward from the implant socket and separating it from the bone of the sinus floor, the bone graft material delivered through the implant socket lifts the sinus floor and allows the implant to be placed while completing the bone graft, but if the bone is thin enough to provide the initial stability of the implant, a second-stage implant restoration can be chosen. This procedure is simple, less invasive and has a shorter operative time, but the elevation height is smaller.