Preparation Of Ceramic Brackets Coated With Nano-tiO₂Thin Films And Its Antibacterial Assay

Fixed appliance plays a very important role in the process of orthodontic treatment. By far, there are three kinds of brackets, which are metal brackets, ceramic brackets and plastic brackets. However, plastic brackets haven’t been put into extensive clinical application due to the bad strength. Although the material property of metal brackets is much better, the aesthetic property is lower than that of ceramic brackets. Most orthodontic patients are adults, especially women. Because of their professions and other reason (like social intercourse), those patients require a more invisible and aesthetical treatment. Due to the color of ceramic brackets is close to the natural tooth color, thus become the first choice of those patients.However, the irregularities of the brackets can result in increased dental plaque formation, thus induce enamel demineralization and other complications during orthodontic treatment. Therefore, plaque control plays an important role in the process of demineralization prevention.Objective:In this study, the TiO2thin film was prepared and studied on the ceramic brackets. We hope to use the photocatalytic antibacterial activity to reduce the attachment of bacterium around the ceramic brackets. Thereby, reduce the prevalence of the orthodontic complications during the treatment. In the meantime, the as-prepared thin films would not affect the color the ceramic brackets.Methods:(1) The sol-gel spin coating method was used to prepare TiO2thin film on the surface of ceramic brackets. Twenty groups of samples were made according to the experimental parameters.(2)The crystal structure and surface morphology were characterized by X-ray diffraction, and scanning electron microscopy, respectively.(3)The thickness of the film was examined by surface profilometer. The adhesion and stability of the coatings were examined by scratch test. (4)The photocatalytic properties under UV light irradiation were evaluated by measuring the degradation ratio of methylene blue.(5)Antibacterial activities of the selected thin films were also tested against Lactobacillus acidophilus and Candida albicans.Results:(1) The TiO2thin films were successfully prepared on the surface of ceramic brackets.(2)The as-prepared thin films were found to be continuous and uniformly distributed. The structure was also compact and homogeneous.(3) The adhesion of the thin film to the substrates was found to be strong.(4) The TiO2thin film has great antibacterial activity to Lactobacillus acidophilus and Candida albicans in vitro.Conclusion:The as prepared thin film has strong adhesion ability to the ceramic brackets. And the coating would not affect the original color of the ceramic brackets, which can meet the requirements of clinical application. Meanwhile, the as-prepared samples can kill common oral pathogenic bacteria, to reduce orthodontic complications.