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

2 Post graduate student, Department of orthodontics,school of dentistry,Tabriz university of medical science

3 Assistant professor, Department of endodontics,school of dentistry,Tabriz university of medical science



Aim: Friction accompanies all sliding techniques. Sliding is in the manner of tipping and uprighting with increasing angle between bracket and wire. Recently, wire coating with the different nanoparticles has been proposed to decrease the frictional forces. The present study was done to coat the stainless steel wires with the ZnO nanoparticles and determine the effect of this coating on friction reduction during different angle between the wires and brackets.
Materials and Methods: Eighty pieces of 0.016 stainless steel wires with and without zinc oxide nanoparticles were used in 80 pieces of orthodontic brackets (0.018). The coated wires analyzed by the SEM and XRD observations. Friction between the wires and orthodontic brackets at 0,5,10 degree angle were calculated using universal testing machine. Two and three group comparisons were done by means of Student t and one-way ANOVA respectively and Tukey post hoc test was used to assess the paired comparisons. 
Results: Frictional values were significantly increased with the increased angles between the wire and bracket. The increased friction force from 0 to 10 degree in uncoated wires were Statistically more significant than increased friction force from 0 to 10 degree in coated wires (p<0.005).
Conclusion: considering the positive effects of zinc oxide nanoparticles coating in decreasing frictional forces, they might offer a novel opportunity to significantly reduce friction during sliding and consequent better anchorage control, reduced risk of root resorption.