Abstract: A device for anchoring to the upper jaw bone dental prostheses of the upper dental arch using a plurality of intraosseous screws each provided with a thread and a bottom shank. A crosspiece with a plurality of nuts corresponding to the number of intraosseous screws are connected together by means of spacers, each nut having a female thread corresponding to the thread of a respective intraosseous screw. A lock nuts corresponding to the number of intraosseous screws are each provided with a female thread in turn corresponding to the thread of the respective screw. The crosspiece is designed to be inserted and housed, during use, in the maxillary sinus and the each screw is inserted inside a respective hole through the bone underneath the maxillary sinus so that it projects beyond the inner cortex of the bone and is inserted inside the respective nut of the crosspiece.