title: Preparation and antimicrobial assay of ceramic brackets coated with TiO2 thin films.
abstract: OBJECTIVE
  Different methods have been utilized to prevent enamel demineralization and other complications during orthodontic treatment. However, none of these methods can offer long-lasting and effective prevention of orthodontic complications or interventions after complications occur. Considering the photocatalytic effect of TiO2 on organic compounds, we hoped to synthesize a novel bracket with a TiO2 thin film to develop a photocatalytic antimicrobial effect.
  
  
  METHODS
  The sol-gel dip coating method was used to prepare TiO2 thin films on ceramic bracket surfaces. Twenty groups of samples were composed according to the experimental parameters. Crystalline structure and surface morphology were characterized by X-ray diffraction and scanning electron microscopy, respectively; film thickness was examined with a surface ellipsometer. The photocatalytic properties under ultraviolet (UV) light irradiation were analyzed by evaluating the degradation ratio of methylene blue (MB) at a certain time. Antibacterial activities of selected thin films were also tested against Lactobacillus acidophilus and Candida albicans.
  
  
  RESULTS
  Films with 5 coating layers annealed at 700℃ showed the greatest photocatalytic activity in terms of MB decomposition under UV light irradiation. TiO2 thin films with 5 coating layers annealed at 700℃ exhibited the greatest antimicrobial activity under UV-A light irradiation.
  
  
  CONCLUSIONS
  These results provide promising guidance in prevention of demineralization by increasing antimicrobial activities of film coated brackets.
authors.affiliation: Department of Orthodontics, School of Dentistry, Lanzhou University, Lanzhou, P. R. China.
authors.forename: Shuai
authors.initials: S
authors.lastname: Cao
authors.affiliation: Department of Orthodontics, School of Dentistry, Lanzhou University, Lanzhou, P. R. China.
authors.forename: Ye
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Orthodontics, School of Dentistry, Lanzhou University, Lanzhou, P. R. China.
authors.forename: Lin
authors.initials: L
authors.lastname: Cao
authors.affiliation: Department of Orthodontics, School of Dentistry, Lanzhou University, Lanzhou, P. R. China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Orthodontics, School of Dentistry, Lanzhou University, Lanzhou, P. R. China.
authors.forename: Bingpeng
authors.initials: B
authors.lastname: Lin
authors.affiliation: Department of Physics, School of Physical Science and Technology, Lanzhou University, Lanzhou, P. R. China.
authors.forename: Wei
authors.initials: W
authors.lastname: Lan
authors.affiliation: Department of Orthodontics, School of Dentistry, Lanzhou University, Lanzhou, P. R. China.
authors.forename: Baocheng
authors.initials: B
authors.lastname: Cao
keywords: Antibacterial; Biomaterial science; Ceramic brackets; Esthetics