the effect of zno nanoparticle coating on the frictional resistance between orthodontic wires and ceramic brackets

introduction: any decrease in friction between orthodontic wire and bracket can accelerate tooth movement in the sliding technique and result in better control of anchorage. the present study was carried out to decrease this friction by coating of zinc oxide nanoparticles (zno) on orthodontic wires and porcelain brackets. materials and methods: in this in vitro study, a combination of 120 0.019×0.025 stainless steel(ss) orthodontic wires and porcelain brackets of 0.022 system with and without spherical zinc oxide nanoparticle coating were evaluated. spherical zno nanoparticles were deposited on wires and brackets by immersing them in ethanol solution and sem (scanning electron microscope) evaluation confirmed the presence of the zno coating. the frictional forces were calculated between the wires and brackets in four groups: group zz (coated wire and bracket), group oo (uncoated wire and bracket), group zo (coated wire and uncoated bracket) and group oz (uncoated wire and coated bracket).kolmogorov-smirnov, kruskal-wallis and mann-whitney tests were used for data analysis. results: the frictional force in zz (3.07±0.4 n) was the highest (p<0.05) and oz (2.18±0.5 n) had the lowest amount of friction(p<0.05) between the groups .there was no significant difference in the frictional forces between the zo and oo groups 2.65±0.2and 2.70±0.2 n respectively . conclusion: the coating of zno nanoparticles on the surface of porcelain brackets can decrease friction in the sliding technique . key words: friction , orthodontics, porcelain, wire, zno