In this operation performed by Dr. Hinze (Munich) implants are placed into the sinus on both sides in the upper jaw. On the right side an external sinus lift is conducted while on the left side the sinus lift is performed internally (Summer technique). On the right side a full flap is prepared initially and the lateral wall of the sinus removed and elevated. BioOss is placed into the elevated sinus floor using a prefilled syringe. With the help of a prefabricated navigated splint the implant cavities are drilled and the 3i implants inserted. After closing the sinus window with a BioGuide membrane the flap is closed with double sling sutures. On the left side again a full flap is raised and the position of the implants marked using the 3D template mentioned above. While placing the implant in position of the upper left second premolar into the residual bone the implant cavity of the upper left first molar is widened to 3 mm and then a cylindrical osteotome is used to gently tap the compact layer of the sinus floor apically. Xenogenic bone (BioOss) is used as a cushion to slowly lift the Schneiderian membrane from the floor further, whereby roughly three BioOss filling tapped coronally increases the vertically gained length by 5 mm. The implant cavity is finalised and the implant inserted. Double sling sutures ensure a stable wound closure.