Evaluation Of Bonding Strength And Antibacterial Property Of Orthodontic Brackets Coated With Nitrogen-doped TiO₂Film

Our research group has successfully produced the anatase nitrogen-doped TiO2-xNx thin film on the surface of MBT metal brackets by using JZCK-580high-vacuum magnetron sputtering equipment. The aim of the present study was to evaluate bonding strength and antibacterial property of bracket coated with nitrogen-doped TiO2-xNx film and to offer foundations for clinical applications. The present study including three sections:1.The preparation and characterization of samples coated with nitrogen-doped TiO2-xNx filmThe nitrogen-doped TiO2thin film was deposited on the metal brackets using the JZCK-580high-vacuum magnetron sputtering equipment. The obtained samples coated with nitrogen-doped TiO2thin film were annealed in nitrogen at450℃for2hours to obtain the antibacterial samples coated with nitrogen-doped TiO2thin film. The scanning electron microscope, the energy-dispersive X-ray spectrometry was employed to investigate the surface morphology, the element composition and crystalline form of the nitrogen-doped TiO2thin film which was coated on the surface of the samples. The result showed that the appearance of the nitrogen-doped TiO2thin film which was coated on the surface of the samples was blue-green color.The film was smooth and compact. The film mainly consists of titanium, oxygen and nitrogen. The catalysts were anatase and in nanometer scale.2. Evaluation of Bonding Strength of The Nitrogen-doped TiO2-xNx Films On Orthodontic BracketsThe structure and surface morphology of3types brackets were evaluated by X-ray diffraction (XRD).The base plate of brackets were to observed by scanning electron microscopy (SEM).3types brackets (ordinary stainless steel brackets, the nitrogen-doped TiO2films on brackets before annealing and the brackets after annealed)were divided in2groups:distilled water at room temperature, thermal cycling. Brackets of all6groups were bonded to60extracted human premolars with Jing-Jin enamel adhesive (n=10each). All bonded specimen were tested on electronic universal testing machine to determine the bond strength. The results were:The TiO2-xNx thin films on brackets were in anatase phase, Grain size for30nm. There were no differences among the base plate3types brackets. The ANOVA test showed the bond strength of the brackets were decreased significantly after thermal cycling(P<0.01). There were no significant differences among the3groups in the same storing methods(P>0.05). The bonding strength of the nitrogen-doped TiO2films on brackets were not under the influence of preparation process, and sufficient for clinical application.3.Antibacterial property of The TiO2-xNx Films On Orthodontic BracketsOur research group has successfully produced the anatase nitrogen-doped TiO2thin film on the surface of MBT metal brackets by using JZCK-580high-vacuum magnetron sputtering equipment. The bonding strength of the nitrogen-doped TiO2films on brackets were not under the influence of preparation process, and sufficient for clinical application. The nitrogen-doped TiO2film coated on brackets showed a good antimicrobial properties.