Frictional Resistance in Self-ligating Orthodontic Brackets and Conventionally Ligated Brackets (An In Vitro Study)


This study was aimed to compare static frictional forces generated by 3 types of brackets (conventional, active self-ligating and passive self-ligating) combined with 3 different sizes of stainless steel wire. Material and Methods: The sample consisted of three types of brackets (Equilibrium 2, Empower, discovery sl) with a slot size 0.022 inch were coupled with 0.020, 0.018×0.025 and 0.019×0.025 inches stainless steel wires, The testing model consists of 6 brackets used to represent lower anterior teeth. Ten tests were carried out for each group of bracket-wire combination in dry state, frictional force were measured by tensile testing machine. A significant P value of 0.05 was predetermined. Results: self-ligating brackets produced significantly lower value (P ≤0.05) of mean of static friction than elastomerically tied conventional bracket. The frictional force increased proportionally to the wire size. Conclusions: The method of ligation appears to be the primary variable responsible for the frictional resistance generated by these types of brackets