Tehran University of Medical Sciences Frontiers in Dentistry 2676-296X 21 0 2024 04 08 1 10 Pooya Ebrahimi 1. Student Research Committee, Faculty of Dentistry, Tabriz University of Medical Sciences, Tabriz, Iran 2. Department of Orthodontics, Faculty of Dentistry, Tabriz University of Medical Sciences, Tabriz, Iran Parastou Nastarin Department of Orthodontics, Faculty of Dentistry, Tabriz University of Medical Sciences, Tabriz, Iran Mahdi Hadilou Student Research Committee, Faculty of Dentistry, Tabriz University of Medical Sciences, Tabriz, Iran Behnaz Karimzadeh Student Research Committee, Faculty of Dentistry, Tabriz University of Medical Sciences, Tabriz, Iran Mojgan Kachoei Department of Orthodontics, Faculty of Dentistry, Tabriz University of Medical Sciences, Tabriz, Iran 2022 02 11 2023 04 08 Objectives: The reduction of resistance to sliding between the archwire and bracket promotes more seamless tooth movement, leading to a faster and improved orthodontic treatment experience. This research aimed to examine how the degradation of elastomeric modules, different ligation methods, bracket-wire angle, and wire type (nickel titanium, NiTi or stainless-steel, SS) impact the kinetic friction resulting from the interaction between NiTi or SS archwires and SS brackets. Materials and Methods: The current in vitro study was conducted on nine groups, including NiTi and SS archwires with three types of ligations (O-ring, figure of 8, and SS wire ligature) and two bracket-wire angles (0˚ and 10˚). The kinetic friction in each group was measured using a Universal Testing Machine at four time intervals: baseline, day one, week one, and week four. Repeated measures ANOVA, Mauchly test of sphericity followed by the Greenhouse-Geisser test, and relevant post hoc tests were used for statistical analysis (P<0.05). Results: The authors found a decrease in kinetic friction in all types of ligations, which confirmed the effect of time on the degradation of ligation modules. The kinetic friction of figure of 8 ligations was higher than both O-ring and SS wire ligations. No difference was observed between O-ring and SS wire ligations. Furthermore, the bracket-wire angle did not affect friction. Conclusion: The authors suggest that the use of figure of 8 ligations in NiTi and SS wires should be limited due to their high friction and replaced with other types of ligations, if possible. https://fid.tums.ac.ir/index.php/fid/article/view/4390 https://fid.tums.ac.ir/index.php/fid/article/download/4390/2039