Reducing Frictional Resistance between Orthodontic Bracket and Arch Wire

Abstract

This investigation evaluated a proposed clinical method for decreasing frictional resistance between an orthodontic bracket and an archwire during usage of the continuous edgewise method of space closure. It was hypothesized that altering the leading edge of the bracket (in the direction of retraction) would significantly decrease the force required to retract a bracket along an archwire at several angulations. Fifteen medium twin brackets with .018 inch slots from three manufacturers were tested on an Instron testing machine, and the force needed to overcome binding friction at five angulations on an .016 inch wire was recorded and submitted for statistical analysis. In addition, the edge of each bracket was partially immersed into the electrolytic solution of the Esmadent bracket and band reconditioner and reduced for one minute. These brackets were then retested twice: once with the reduced edge leading and once with the reduced edge rotated 180° so that it was trailing. There was a statistically significant difference between manufacturers as well as between procedures. The reduced leading bracket edge resulted in the greatest decrease in friction. These differences were significant at the p<.01 level. The advantage of reducing only one edge of the bracket instead of both, is that the unaltered wing allows maximum slot engagement with the larger wires normally utilized during finishing. This study provided a rationale as well as a procedure for the clinician to selectively alter aspects of stock bracket configuration to meet the needs of decreased friction as well as total control.