Polyphenylene polymers as esthetic orthodontic archwires

Introduction: There is continuing interest in an esthetic, effective labial archwire. In this study, we evaluated the potential of new, high-strength polyphenylene polymers to fill this need. Methods: Polyphenylene (Primospire, Solvay Advanced Polymers, Alpharetta, Ga) polymer was extruded into wires with clinically relevant round and rectangular cross sections. Tensile, flexure, spring-back, stress-relaxation, and formability characteristics were assessed. Arch forms and secondary shapes were formed. Results: Smooth wires with consistent cross-sectional dimensions, high spring-back, and good ductility were produced. Forces delivered were generally similar to typical beta-titanium and nickel-titanium wires of somewhat smaller cross sections. The polyphenylene wire did experience stress relaxation for up to 75 hours. The force magnitudes place polyphenylene wires in the category of an alignment or leveling wire. High formability allowed shape bending similar to that associated with stainless steel wires. Conclusions: Polyphenylene polymers could serve as esthetic orthodontic archwires; further study is warranted. (Am J Orthod Dentofacial Orthop 2011; 139:e391-e398)