title: In vitro evaluation of the effectiveness of bleaching agents activated by different light sources.
abstract: OBJECTIVE
  This study evaluated the efficacy of tooth whitening and color stability at different time periods after treatment.
  
  
  METHODS
  Blocks obtained from human molars were divided into 15 groups (n = 5) by bleaching agents: 35% hydrogen peroxide (Whiteness HP and Opalescence Xtra) and 37% carbamide peroxide (Whiteness Super); and light sources: halogen lamp and plasma arc lamp (bleach mode), LED/diode laser, argon laser, and no light source. The efficacy of bleaching was measured using a spectrophotometer. Six bleaching sessions were performed (times 1 to 6). The specimens were submitted to another reading 7, 15, and 30 days after the end of bleaching (times 7, 8, and 9). The results were submitted to ANOVA followed by Tukey test and polynomial regression (p < 0.05).
  
  
  RESULTS
  Carbamide peroxide significantly differed from hydrogen peroxide, presenting low reflectance values. Activated versus non-activated bleaching did not differ significantly for any gel tested, except for Whiteness HP activated by argon laser, which presented the lowest mean reflectance values. The results obtained with hydrogen peroxide revealed a decrease in reflectance values one month after the end of treatment. For carbamide peroxide, this decrease was not observed.
  
  
  CONCLUSIONS
  The halogen lamp presented the same or higher efficacy than non-activated bleaching, which had a longer gel contact period. When hydrogen peroxide was used, a decrease in reflectance values was observed 30 days after the end of bleaching.
authors.affiliation: Department of Restorative Dentistry, Piracicaba School of Dentistry, Campinas State University, Sao Paulo, Brazil. debora1201@yahoo.com.br
authors.forename: Débora Alves Nunes Leite
authors.initials: DA
authors.lastname: Lima
authors.forename: Flávio Henrique Baggio
authors.initials: FH
authors.lastname: Aguiar
authors.forename: Priscila Christiane Suzy
authors.initials: PC
authors.lastname: Liporoni
authors.forename: Egberto
authors.initials: E
authors.lastname: Munin
authors.forename: Gláucia Maria Bovi
authors.initials: GM
authors.lastname: Ambrosano
authors.forename: José Roberto
authors.initials: JR
authors.lastname: Lovadino
mesh_terms: D000077463:Carbamide Peroxide; D003116:Color; D003743:Dental Enamel / Q000187:drug effects* / Q000528:radiation effects; D004338:Drug Combinations; D006801:Humans; D006861:Hydrogen Peroxide / Q000528:radiation effects / Q000627:therapeutic use; D054018:Lasers, Excimer / Q000627:therapeutic use; D054023:Lasers, Semiconductor / Q000627:therapeutic use; D008029:Lighting / Q000295:instrumentation*; D008422:Materials Testing; D016877:Oxidants / Q000528:radiation effects / Q000627:therapeutic use*; D010545:Peroxides / Q000528:radiation effects / Q000627:therapeutic use; D013053:Spectrophotometry; D013997:Time Factors; D014073:Tooth Bleaching / Q000295:instrumentation* / Q000379:methods; D014508:Urea / Q000031:analogs & derivatives / Q000528:radiation effects / Q000627:therapeutic use
chemical_list: D004338:Drug Combinations; D016877:Oxidants; D010545:Peroxides; D000077463:Carbamide Peroxide; D014508:Urea; D006861:Hydrogen Peroxide