Abstract: We describe systems and methods that allow absolute security of the stability of screwing by screws when access to said screw is possible neither from the side nor from beneath. Said stability is achieved in a reversible way in the sense that unscrewing can easily be performed without breaking when needed. A variety of systems and methods are disclosed with these attribute, which can in particular apply to the trans-screwing of a prosthetic abutment on the crestal end of a dental implant, with many more applications.