Effect of elastomeric module degradation and method of ligation on friction between Ni-Ti or Stainless Steel wires and Stainless Steel brackets

Abstract

Introduction: Less friction between the archwire and the bracket makes the teeth movement easier and ultimately accelerates and improves the quality of orthodontic treatment. However, few studies have been performed on the role of friction between different types of ligaments over time in the first phase of orthodontic treatment using Ni-Ti archwires. The aim of this study was to investigate the Effect of elastomeric module degradation and method of ligation on friction between Ni-Ti or Stainless Steel (SS) wires and stainless steel brackets. Methods and Materials: This experimental-laboratory study was performed on 9 groups including standard 0.022 steel system brackets in two types of wires including 60 round 0.016 inch Ni-Ti wires with two types of zero and 10 degrees between wire-bracket (6 groups) and 30 SS 0.019×0.025 inch wires with zero degree between wire-bracket (3 groups), and three types of ligations including O-Ring, O-Ring: figure of 8 and wired steel ligature. The friction amount of each group was measured using the Universal Testing Machine during a month at different time intervals (Immediately, 1 day, 1 week and 4 weeks after ligation closure). Results: In this study, the findings confirmed the effect of time on ligature decay over time and showed that among the three types of Ni-Ti wire ligations (O-Ring, O-Ring: figure of 8, and wired steel ligature) in both types of wire-bracket angles of zero and ten degrees, the amount of friction O-Ring: figure of 8 ligation was significantly higher than other ligations (P<0.05). Among the three types of SS wire ligations (O-Ring, O-Ring: figure of 8, and wired steel ligature) in the zero-degree wire-bracket angle, the friction of O-Ring: figure of 8 ligation was also significantly higher than other ligations (P<0.05). At different angles of the Ni-Ti wire (0 and 10 degress), there was no significant diffrenstes between two O-Ring ligations as 0 and 10 degress (P=0.980), between two O-Ring: figure of 8ligations as 0 and 10 degress (P=0.802), and between two wired steel ligatures as 0 and 10 degress (P=1.000). Conclusion: The O-Ring: figure of 8 ligation in Ni-Ti and SS wires has higher rate of friction than other types of ligaments, and more orthodontic force is applied to overcome the friction.