Static and Dynamic Friction Comparison of Esthetic Orthodontic Archwires

Objective: The study objective was to investigate what type of esthetic orthodontic wire coating provides less frictional resistance when used with ceramic polycrystalline brackets compared to each other and to non-coated stainless steel archwire. Consistency of wire sizes with dimensions reported by manufacturers, and effect of stainless steel core diameter on frictional characteristics were also investigated. Methods: Canine retraction model was constructed allowing to simulate forces and conditions existing on the bracket/wire interface during orthodontic tooth movement. Static and kinetic resistance to sliding of three coated archwires from different manufacturers was measured using Instron testing machine and compared to each other and non-coated stainless steel control wire. Dimensions of wires as received and diameter of stainless steel core after coating removal was measured with optical profile projector. Results: Significant differences exist in static and kinetic friction between tested wires in experimental conditions. Dimensions of all coated wires differ significantly from reported by manufacturers’ sizes. Conclusions: Type of esthetic coating effects frictional characteristics of orthodontic wires and should be considered by clinicians for predictable treatment outcomes.