Abstract: An attachment assembly for securing a dental prosthetic device to an implant includes a post having a through bore which is adapted to be secured in a recess in the prosthetic device, a primary fastening screw having a head for engagement in the through bore and a threaded shaft for projecting out of the through bore for threaded engagement in a correspondingly threaded bore of an implant or implant abutment, and a locking insert member for securing in the post through bore above the primary screw with a lower end face of the insert member bearing against the upper end face of the screw head in order to resist loosening of the screw member once fastened to the implant.