title: [The efficacy of cold-light tooth bleaching on the formation of bacteria biofilm on the enamel surfaces].
abstract: OBJECTIVE
  To evaluate the efficacy of Beyond cold-light tooth bleaching on the formation of main cariogenic bacteria biofilm on enamel surfaces.
  
  
  METHODS
  Twenty enamel discs with the size of 4 mm×4 mm×1 mm in size, were made. The enamel discs were divided into 4 groups randomly: cold-light bleaching group, bleaching gel group, cold-light group and control group. Five discs were in each group. Cold-light bleaching group was whitened 3 times with bleaching gel and cold-light, and 12 min per session. Bleaching gel was smeared on the surface of enamel in bleaching gel group for 3 times and 12 min per session. Enamel discs of cold-light group were treated with cold-light for 12 min and 3 sessions. Control group was treated without any processing. The 4 groups were incubated in mixed bacteria liquid, including Streptococcus mutans(SM), Actinomyces viscosus (Av) and Fusobacterium nucleatum (Fn), within the artificial oral cavity model. After 36 h, the samples were observed under confocal laser scanning microscopy(CLSM). The data was analyzed with SAS8.2 software package.
  
  
  RESULTS
  The biofilms in 3 experimental groups were sparser than the control group under CLSM, and the thickness significantly decreased after treatment (P<0.05), while no significant difference was found among 3 experimental groups (P>0.05).Compared with the control group, the percentage of vital bacteria in biofilm of the experimental groups decreased significantly after treatment (P<0.001).
  
  
  CONCLUSIONS
  Cold-light tooth bleaching can inhibit the formation of mixed bacteria biofilm, damage the structure of biofilm and reduce the number of vital bacteria. Supported by Research Fund of Ninth People's Hospital of Shanghai Jiao Tong University School of Medicine (2013-06).
authors.affiliation: Department of Endodontics, Shanghai Ninth People's Hospital, College of Stomatology, Shanghai Jiao Tong University School of Medicine. Shanghai 200011;China.E-mail:ykyong6@163.com.
authors.forename: Ke-yong
authors.initials: KY
authors.lastname: Yuan
authors.forename: Rui
authors.initials: R
authors.lastname: Ma
authors.forename: Cai-lian
authors.initials: CL
authors.lastname: Zhu
authors.forename: Ming-yu
authors.initials: MY
authors.lastname: Li
authors.forename: Zhi-yan
authors.initials: ZY
authors.lastname: He
authors.forename: Wei
authors.initials: W
authors.lastname: Zhou
mesh_terms: D016924:Actinomyces viscosus; D018441:Biofilms; D003743:Dental Enamel; D016967:Fusobacterium nucleatum; D008027:Light; D013295:Streptococcus mutans; D014073:Tooth Bleaching