Resumen de Effectiveness of dental bleaching in depth after using different bleaching agents

Maria Beatriz Freitas D'Arce, Débora Alves Nunes Leite Lima, Flávio Henrique Baggio Aguiar, Eduardo dos Santos Bertoldo, Gláucia María Bovi Ambrosano, José Roberto Lovadino

• Objectives:

  This study evaluated the effectiveness of low- and high-concentration bleaching agents on enamel and deep dentin.

  Study design:

  Stained bovine incisors fragments were randomized placed into 10 groups (n=5), according to the sample thicknesses (2.0 mm or 3.5 mm) and bleaching agent: 10% carbamide peroxide (CP) (4 h a day/21 days);

  6% hydrogen peroxide (HP) with calcium (1:30 h a day/21 days); HP 20% with calcium (50 min a day/3 sessions with a 7-day interval); HP 35% (3 x 15 min a day/3 sessions with a 7-day interval); HP 35% with calcium (40 min a day/3 sessions with a 7-day interval). The samples were stored in artificial saliva during the experiment. The co - lor change was evaluated using a spectrophotometer at the initial analysis, after artificially staining with black tea and after each of the bleaching weeks, and data was expressed in CIE Lab System values. The L* coordinate data was submitted to analysis of variance and Tukey-Kramer test and the ?E values data was submitted for analysis of variance in a split-plot ANOVA and Tukey's test (α=0.05).

  Results:

  None of the bleaching agents tested differed from the reflectance values on the enamel surface. For deep dentin HP 20% and HP 35%, both with calcium, showed the lowest reflectance values, which differed from CP 10%.

  Conclusion:

  It is concluded that high concentration hydrogen peroxide with calcium was less effective in deep dentin than 10% carbamide peroxide.