The cortical bone plate of the chin is tried out and adjusted with burrs. If the floor of the sinus is very thin it may be necessary to make an inlay and an onlay at the same time to allow for proper fixation of transplanted bone. The adjusted donor bone is kept in place at or on the floor of the sinus by the use of a 1.5 mm screw fixation (*). The screws are easily removed at the time of implant placement.

The surplus of cortical bone and the harvested bone chips from symphysis and tuberosities are grinded in a bone mill (*). The cortical plate of the antral wall is preserved.