A tool for detaching the Schneiders membrane from the sinus floor has a syringe (2) for an isotonic saline solution, a head unit (3) and a flexible tube (1) connecting the syringe (2) to the head unit (3). The head unit (3) comprises a terminal tract (4) of the flexible tube (1) having a distal end (40) and a proximal end (41) and being provided with two radial holes (6), an end element (5), which closes the terminal tract (4) in its distal end (40), the end element projecting radially with respect to the terminal tract (4) and working laterally without any direct impact onto the Schneider membrane from the side of the sinus floor (ps), and an abutment member (7) being coaxial to the flexible tube (1) and intended to abut the maxillary bone (om) on the side opposite to the Schneiders membrane ( ms ), so as to keep patent the two radial holes (6).
