title: Tooth discoloration induced by endodontic phenothiazine dyes in photodynamic therapy.
abstract: OBJECTIVE
  This study sought to assess if discoloration of tooth structures occurs after photodynamic therapy (PDT) and to determine the efficacy of a protocol to remove the photosensitizers.
  
  
  BACKGROUND
  PDT has been used in root canal treatment to enhance cleaning and disinfection of the root canal system. PDT uses a low power laser in association with a dye as a photosensitizer. Photosensitizers can induce staining of the dental structures, resulting in an unaesthetic appearance.
  
  
  METHODS
  Forty teeth were randomly divided into four groups according to the photosensitizer used and pre-irradiation time: 0.01% methylene blue for 5 min (MB5); 0.01% methylene blue for 10 min (MB10); 0.01% toluidine blue for 5 min (TB5); and 0.01% toluidine blue for 10 min (TB10). Specimens were irradiated with a 660 nm diode laser with a 300 μm diameter optical fiber, at 40 mW power setting for 3 min. Immediately after, the photosensitizers were removed with Endo-PTC cream+2.5% sodium hypochlorite (NaOCl). The shade was measured by a Vita Easyshade spectrophotometer based on the CIELAB color system (L*a*b* values) at three different experimental times: before PDT (T0), immediately after PDT (T1), and after removal of the photosensitizer (T2).
  
  
  RESULTS
  The results showed a decrease in the averages of the L*a*b* coordinate values after PDT (T1) in all the groups, when compared with the number at T0, with a significant statistical difference in group MB10. After photosensitizer removal (T2), all the values of the coordinates increased with significant statistical differences (p<0.05) between T1 and T2 in L* and a*.
  
  
  CONCLUSIONS
  It can be concluded that both methylene blue and toluidine blue dyes cause tooth discoloration, and that Endo-PTC cream associated with 2.5% NaOCl effectively remove these dyes, regardless of the pre-irradiation time used for PDT.
authors.affiliation: 1 Department of Dentistry, University of Taubate , Taubate, São Paulo, Brazil .
authors.forename: Rômulo Aguiar
authors.initials: RA
authors.lastname: Figueiredo
authors.forename: Lilian Costa
authors.initials: LC
authors.lastname: Anami
authors.forename: Isabel
authors.initials: I
authors.lastname: Mello
authors.forename: Erica dos Santos
authors.initials: Edos S
authors.lastname: Carvalho
authors.forename: Sandra Márcia
authors.initials: SM
authors.lastname: Habitante
authors.forename: Denise Pontes
authors.initials: DP
authors.lastname: Raldi
mesh_terms: D004396:Coloring Agents / Q000009:adverse effects; D006801:Humans; D008751:Methylene Blue / Q000009:adverse effects; D010778:Photochemotherapy; D014048:Tolonium Chloride / Q000009:adverse effects; D014075:Tooth Discoloration / Q000209:etiology*
chemical_list: D004396:Coloring Agents; D014048:Tolonium Chloride; D008751:Methylene Blue