Comparative Frictional Resistance of Conventional, Self-Ligating, and Ceramic Orthodontic Brackets with Different Archwires: An In-Vitro Study
Keywords:
Orthodontic friction; self-ligating brackets; ceramic brackets; archwire; sliding mechanics; nickel-titanium; stainless steel.Abstract
Background The bracket-archwire interface friction affects the force for orthodontic tooth movement during sliding mechanics. The material of the brackets, type of ligation, and the thickness of the archwire can vary in resistance to the sliding action of the ligature, and may thus influence the choice of the force. Objective This study aimed to compare static and kinetic frictional resistances of conventional stainless-steel, passive self-ligating stainless-steel and monocrystalline ceramic brackets against three clinically common archwires. Materials and Methods A laboratory model with 108 bracket-wire specimens was designed as a 3 × 3 factorial experiment with 12 specimens per combination. The slots were all 0.022”. The archwires were 0.014-inch nickel-titanium (NiTi), 0.016 × 0.022- inch NiTi, and 0.019 × 0.025-inch stainless steel (SS). Standardized elastomeric modules were used to ligate the conventional metal and ceramic brackets, while the passive self-ligating brackets were tested with their built-in clips. Artificial saliva was used at 37 °C and the testing machine applied a force at 5 mm/min to the specimen: static friction was represented by the peak force required to initiate sliding and kinetic friction by the mean force during the continued sliding. The data were analyzed by two-way ANOVA and Tukey tests (α = 0.05). Results The static friction of passive self-ligating brackets (0.64 ± 0.44 N) was lowest, followed by conventional metal brackets (1.36 ± 0.57 N) and highest for ceramic brackets (1.94 ± 0.78 N). Across bracket systems, mean static friction increased from 0.66 ± 0.39 N with 0.014-inch NiTi to 1.24 ± 0.57 N with 0.016 × 0.022- inch NiTi and 2.03 ± 0.74 N with 0.019 × 0.025-inch SS. All three bracket types, archwire types and their interactions, were statistically significant (all p < 0.001). Overall, the passive self-ligation decreased static friction by ~52.8% when compared to conventional metal brackets. Conclusion In this standard in-vitro setting, passive self-ligating brackets had the lowest resistance to sliding, the ceramic brackets had the highest resistance, and larger rectangular archwires significantly increased friction. When designing the sliding mechanics, therefore, the bracket and wiring needs should be taken into consideration.
Bangladesh Journal of Medical Science Vol. 25 No. 04 October’26 Page: 1332-1337
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Copyright (c) 2026 Kuraym Alenazi, Abdulrahman Shqaidef, Eyas Muti Omar Abuhijleh, Mohammad Khursheed Alam
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