A screw lock for single-tooth implant superstructures

Background. The most common complication in a single-tooth implant restorat ion is abutment screw loosening. Instability of the prosthetic superstructu re is expressed by difficulty in chewing and functioning, as well as soft-t issue soreness and/or swelling that could lead to screw fracture. Manufactu rers of oral implants have attempted to refine connecting parts of the pros thesis to achieve a more predictable tightening method for the screws. Methods. To maintain the abutment screw tightly in its correct position, th e authors developed a technique in which an elongated hexagonal titanium ba r is inserted into the hexed fixed screw head. The screw is locked, and the bar is then fixed with a light-cured composite resin material that serves to seal the retaining screw access hole. The occlusal hexagonal bar thus se rves as a secure screw lock that can be easily removed if needed. Results. The authors have used the hexagonal bar for almost three years on 120 single-tooth screw-retained prostheses in 100 patients (65 in the first and second premolar region, 40 in the incisor region and 15 in the posteri or molar region). All of these prostheses functioned successfully, includin g those with wider occlusal planes and increasing occlusal forces. No screw loosening or fractures were noted in any of the fixtures. Clinical Implictions. This technique secures and stabilizes the single-toot h prosthesis, reduces chair time on follow-up procedures and reduces unnece ssary frustration in patients and dental team members.