title: Effectiveness and mode of action of whitening dentifrices on enamel extrinsic stains.
abstract: OBJECTIVE
  This study was conducted in order to investigate the mode of action and the whitening effect of whitening dentifrices.
  
  
  METHODS
  Two hundred fifty-six bovine enamel specimens (10 × 10 mm(2)) were prepared, partially stained, and assigned into eight groups (n = 32): six whitening dentifrices, one nonwhitening and deionized water (negative control), and further divided in two subgroups (n = 16), according to the test model: chemical (dentifrice slurry treatment only) or chemo-mechanical (slurry + toothbrushing). Specimens were treated with dentifrice slurries 2 ×/day for 1 min and toothbrushed or not, according to each model. In between dentifrice treatments, specimens were artificially stained for 5 h. This protocol was repeated for 5 days and enamel color changes (∆E) were measured after each day (days 1-5). The abrasive level of the dentifrices was determined following the ISO11609 guidelines.
  
  
  RESULTS
  In the chemo-mechanical model, the whitening action of all dentifrices was observed after day 1, being higher than the negative control group (p < 0.05). In days 2-5, nonsignificant changes in color were observed for all groups (p > 0.05). Differences on ∆E among dentifrices were observed, and they seemed to correlate well with their abrasive level (r(2) = 0.80). In the chemical model, no significant differences were observed among groups (p > 0.05), with ∆E remaining constant throughout the study. Higher ∆E values were observed in the chemo-mechanical model compared to the chemical (p < 0.05).
  
  
  CONCLUSIONS
  All tested dentifrices were effective in whitening stained enamel and their mode of action showed to be mainly mechanical (toothbrushing abrasion).
  
  
  CONCLUSIONS
  The abrasive level of dentifrices seems to determine its whitening effectiveness.
authors.affiliation: Oral Health Research Institute, Department of Preventive and Community Dentistry, Indiana University School of Dentistry, 415 N. Lansing Street, Indianapolis, 46202-2876, IN, USA.
authors.forename: Salem
authors.initials: S
authors.lastname: Alshara
authors.forename: Frank
authors.initials: F
authors.lastname: Lippert
authors.forename: George J
authors.initials: GJ
authors.lastname: Eckert
authors.forename: Anderson T
authors.initials: AT
authors.lastname: Hara
mesh_terms: D003743:Dental Enamel; D003802:Dentifrices; D006801:Humans; D010865:Pilot Projects; D014073:Tooth Bleaching
chemical_list: D003802:Dentifrices