Friction Performance Of Orthodontic Brackets Coated With N-doped TiO₂ Thin Films

Enamel demineralization is one of the common complication of orthodontic fixed appliance therapy. Because of the complex structure of the bracket prevents cleaning of the teeth, making the soft dirt, plaque around the brackets easy adhesion and aggregation. The same time fixed appliance enables oral microflora environment has changed, causing such as Streptococcus mutans and Lactobacillus, etc. an increase in the number of cariogenic bacteria. In the role of a certain time, acidic substances produced by the bacteria lead to demineralization of enamel appear opaque white change, severe cases can lead to secondary caries damage to dental health. Therefore, the prevention and control of enamel demineralization and other complications has become a hot research scholars orthodontics.In the fixed-treatment process, the friction between the arch wire and bracket is an important factor affecting the tooth movement. Studies suggest that low-friction not only can promote tooth movement, can also reduce the risk of root resorption, but also to shorten the treatment time. Therefore, the evaluation brackets friction properties is essential.Objective:In this paper, by Magnetron Sputtering, on stainless steel metal orthodontic brackets prepared the surface of nano TiO2-xNx films of different thicknesses to simulate three different oral moist environment, the dynamic friction coefficient and static friction coefficient of thin film nano TiO2-xNx brackets were studied, in order to provide the basis for clinical application.Methods:(l)By Magnetron Sputtering, on stainless steel metal orthodontic brackets prepared the surface of nano TiO2-xNx films of different sputtering time.(2)The filmstructure and crystal structure analysis by X-ray diffraction (XRD), and scanning electron microscopy (SEM) to observe the surface morphology of the film.(3)Determination of film thickness, film surface roughness by the surface roughness measuring instrument measured.(4)Use 14FW reciprocating friction tester determination of each group static friction coefficient and dynamic friction coefficient between brackets and arch wires under three different solution wet state and a dry state.Results:(1)By RF magnetron sputtering the nano TiO2-xNx films were successfully prepared on the surface of stainless steel metal orthodontic brackets with different sputtering time.(2) The as-prepared nano TiO2-xNx films were found to be the structure was uniform and dense, also is anatase structure.(3) The adhesion of the nano TiO2-xNx films to the substrates was found to be good.(4) The nano TiO2-xNx film brackets showed significant friction reduction effect under dry and lubricated conditions.Conclusion:By using RF magnetron sputtering successfully prepared nano TiO2-xNx film brackets with different sputtering time. The as-prepared nano TiO2-xNx films was anatase, the structure was uniform and dense. The static friction coefficient and dynamic friction coefficient of different thickness nano TiO2-xNx film brackets regardless of under dry or wet conditions were less than the control group. In the same moist environment, with the film thickness increases nano TiO2-xNx film brackets friction coefficient showed a decreasing trend. The nano TiO2-xNx film brackets showed a good low-friction properties.