title: Theoretical optimum of implant positional index design.
abstract: Rotational freedom of the implant-abutment connection influences its screw joint stability; for optimization, influential factors need to be evaluated based on a previously developed closed formula. The underlying hypothesis is that the manufacturing tolerances, geometric pattern, and dimensions of the index do not influence positional stability. We used the dimensions of 5 commonly used implant systems with a clearance of 20 microm to calculate the extent of rotational freedom; a 3D simulation (SolidWorks) validated the analytical findings. Polygonal positional indices showed the highest degrees of rotational freedom. The polygonal profile displayed higher positional stability than the polygons, but less positional accuracy than the cam-groove connection. Features of a maximal rotation-safe positional index were determined. The analytical calculation of rotational freedom of implant positional indices is possible. Rotational freedom is dependent on the geometric design of the index and may be decreased by incorporating specific aspects into the positional index design.
authors.affiliation: Dept. of Oral and Maxillofacial Surgery, Clinical Navigation and Robotics, Charité-Campus Virchow Clinic, Augustenburger Platz 1, 13353 Berlin, Germany.
authors.forename: W
authors.initials: W
authors.lastname: Semper
authors.forename: S
authors.initials: S
authors.lastname: Kraft
authors.forename: T
authors.initials: T
authors.lastname: Krüger
authors.forename: K
authors.initials: K
authors.lastname: Nelson
mesh_terms: D000465:Algorithms; D001696:Biomechanical Phenomena; D017076:Computer-Aided Design; D000044:Dental Abutments; D015921:Dental Implants; D017267:Dental Prosthesis Design; D017268:Dental Prosthesis Retention; D006801:Humans; D021621:Imaging, Three-Dimensional; D008855:Microscopy, Electron, Scanning; D008962:Models, Theoretical; D012399:Rotation; D013499:Surface Properties
chemical_list: D015921:Dental Implants