Abstract: A surgical tool (5) used for preparing a surgical sinus-lift osteotomy has a defined thread geometry in series with an osteotome tip to cut, crack and push bone from the sinus floor upward into the sinus cavity in a tactual, gentle and controlled motion. The apical osteotome tip is driven into a pre-drilled pilot osteotomy after the cutting threads are engaged and rotated until the sinus floor is cracked free. Once the bony sinus floor is cracked free, a fluid passageway can be pressurized with a sterile fluid at a defined pressure to release and push the sinus membrane upward into the sinus cavity to create a desired apical cavity for grafting. The invention solves the problems for preparing a sinus-lift surgical osteotomy and desired cavity space while minimizing the risk of compromising or tearing the sinus membrane.