1 Assistant Professor, Department of Orthodontics, Tabriz University of Medical Sciemces

2 Postgraduate Student, Department of Orthodontics, Tabriz University of Medical Sciences



Aim: Sliding a tooth along an archwire involves a frictional force, causing a number of adverse effects like anchorage loss, excessive orthodontic forces, prolonged treatment time and damage to the roots. This is especially true in ceramic brackets where the friction is notoriously higher.Recently, wire coating with the different nanoparticles has been proposed to decrease the frictional forces. This study evaluated the friction force created between stainless steel
archwires coated with ZnO nanoparticles and ceramic brackets in vitro.
Materials and Methods: Friction tests simulating archwire functioning of the coated and uncoated wires and ceramic brackets were carried out by an Instron machine.Control and case groups included uncoated and coated 0.019×0.025 stainless steel wires respectively. Coating was preformed by inserting stainless steel (SS) wires into solutions of ethanol + zinc oxide. The adhesion properties of the coated wires after friction were analyzed by SEM (scanning electron microscope).The frictional forces were compared usingMann-Whitney test.
Results: In the control group (porcelain brackets + uncoated stainless steel wires) the mean friction force was 2.59 ± 0.37N whereas in case group (porcelain brackets + coated stainless steel wires) the mean friction force was 2.54 ±0.32 N. Although the friction force in coated wires was lower than uncoated wires; the difference between two groups was not statistically significant. (p=0.62). 
Conclusion: coating of stainless steel archwires with ZnO nanoparticles did notcause significant reduction in frictional forces between stainless steel arch wires and ceramic brackets.