title: Bactericidal effect of the photocatalystic reaction of titanium dioxide using visible wavelengths on Streptococcus mutans biofilm.
abstract: BACKGROUND
  The aim of this study was to determine the effect of titanium dioxide (TiO2) photocatalysis induced by the application of clinically acceptable visible light at 405nm on the growth of Streptococcus mutans biofilms.
  
  
  METHODS
  S. mutans biofilms were grown on a hydroxyapatite (HA) disk and deposited in a rutile-type TiO2solution at a concentration of 0.1mg/mL. TiO2photocatalysis was measured for exposure to visible light (405nm) and ultraviolet (UV) light (254nm) produced by light-emitting diodes for 10, 20, 30, and 40min. After two treatments, the number of colonies formed in the final S. mutans biofilm on the HA disk were measured to confirm their viability, and the morphological changes of S. mutans were evaluated using scanning electronic microscopy.
  
  
  RESULTS
  The bactericidal effects of 254- and 405-nm light resulted in > 5-log and 4-log reductions, respectively (p<0.05), after 20min of treatment and a>7-log reduction after 40min of treatment in both treatment groups relative to the control group.
  
  
  CONCLUSIONS
  It was confirmed that the antibacterial effect could be shown by causing the photocatalytic reaction of TiO2in S. mutans biofilm even at the wavelength of visible light (405nm) as at the wavelength of ultraviolet light (254nm).
authors.affiliation: Department of Preventive Dentistry & Public Oral Health, BK21 PLUS Project, Oral Science Research Institute, Yonsei University College of Dentistry, Seoul, Republic of Korea. Electronic address: chanhee@yuhs.ac.
authors.forename: Chan-Hee
authors.initials: CH
authors.lastname: Kim
authors.affiliation: Department of Preventive Dentistry & Public Oral Health, BK21 PLUS Project, Oral Science Research Institute, Yonsei University College of Dentistry, Seoul, Republic of Korea. Electronic address: eunsong@yuhs.ac.
authors.forename: Eun-Song
authors.initials: ES
authors.lastname: Lee
authors.affiliation: Department of Preventive Dentistry & Public Oral Health, Yonsei University College of Dentistry, Seoul, Republic of Korea. Electronic address: simook@yuhs.ac.
authors.forename: Si-Mook
authors.initials: SM
authors.lastname: Kang
authors.affiliation: Department of Preventive Dentistry & Public Oral Health, Yonsei University College of Dentistry, Seoul, Republic of Korea; Department of Health Services Research, University of Liverpool, Liverpool, United Kingdom; Inspektor Research Systems BV, Amsterdam, The Netherlands. Electronic address: e.dejosselindejong@xs4all.nl.
authors.forename: Elbert
authors.initials: E
authors.lastname: de Josselin de Jong
authors.affiliation: Department of Preventive Dentistry & Public Oral Health, BK21 PLUS Project, Oral Science Research Institute, Yonsei University College of Dentistry, Seoul, Republic of Korea. Electronic address: drkbi@yuhs.ac.
authors.forename: Baek-Il
authors.initials: BI
authors.lastname: Kim
mesh_terms: D000900:Anti-Bacterial Agents / Q000008:administration & dosage; D018441:Biofilms / Q000187:drug effects* / Q000254:growth & development* / Q000528:radiation effects; D002384:Catalysis / Q000187:drug effects / Q000528:radiation effects; D004203:Disinfection / Q000379:methods*; D004305:Dose-Response Relationship, Drug; D004307:Dose-Response Relationship, Radiation; D010778:Photochemotherapy / Q000379:methods*; D017319:Photosensitizing Agents / Q000008:administration & dosage; D013295:Streptococcus mutans / Q000166:cytology / Q000187:drug effects* / Q000528:radiation effects*; D014025:Titanium / Q000008:administration & dosage*; D016896:Treatment Outcome
chemical_list: D000900:Anti-Bacterial Agents; D017319:Photosensitizing Agents; C009495:titanium dioxide; D014025:Titanium
keywords: Biofilm; Photocatalysis; Photodynamic therapy; Streptococcus mutans; Titanium dioxide; Ultraviolet light; Visible light