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Quintessence International



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Quintessence Int 33 (2002), No. 5     1. May 2002
Quintessence Int 33 (2002), No. 5  (01.05.2002)

Page 370-375, doi:10.3290/j.qi.a26051

Effects of two 10% peroxide carbamide bleaching agents on dentin microhardness at different time intervals
de Freitas, Patrícia Moreira / Basting, Roberta Tarkany / Rodrigues jr., Antônio Luiz / Serra, Mônica Campos
Objective: The purpose of this in vitro study was to evaluate the microhardness of human dentin exposed to two 10% carbamide peroxide agents at different bleaching times. Method and materials: Opalescence 10% and Rembrandt 10% were tested. A placebo agent was used as a control group. The bleaching and placebo agents were applied to the surface of human dentin fragments for 8 hours and then stored in individual receptacles with artificial saliva for the remaining 16 hours each day. Microhardness testing was performed at baseline, after 8 hours, 7, 14, 21, 28, 35, and 42 days of treatment, and 7 and 14 days posttreatment. Results: Analysis of Variance and the Tukey test revealed significant differences in microhardness values for dentin treated with the agents within each time interval. There was a decrease in the microhardness values of dentin for both bleaching agents after 8 hours of treatment. Fourteen days after the completion of treatment, the microhardness values for dentinal surfaces treated with either Opalescence or Rembrandt reached the baseline values; the dentinal surfaces treated with a placebo exhibited an increase in microhardness values posttreatment. Conclusion: Ten percent carbamide peroxide bleaching agents decreased dentinal microhardness over time, but after 14 days in artificial saliva storage at the completion of treatment, the baseline microhardness values were recovered.