• carbamide peroxide;
  • discoloration;
  • endodontic sealer;
  • intracoronal bleaching;
  • sodium perborate



To evaluate the effect of peroxide-based bleaching agents on teeth stained with AH26 sealer (Dentsply De Trey, Konstanz, Germany), using digital images and computer analysis.


Thirty-five maxillary central incisors were root filled, and the internal walls of the access cavity were coated with AH26 sealer. Internal bleaching commenced 4 months after the root fillings. In three experimental groups (n = 10), the teeth were bleached for 21 days using 45% carbamide peroxide (CP) gel, 45% sodium perborate + carbamide peroxide (SP + CP) or sodium perborate + distilled water (SP + W). No bleaching was undertaken in the control group. Digital images of each specimen were made before treatment, 4 months after endodontic treatment and 2 weeks after bleaching. Colour differences (∆E) were calculated by determining L*a*b* values using digital images and imaging software. Differences between the original colour and sealer-stained teeth, between sealer-stained and bleached teeth and between original colour and bleached teeth were calculated. Data were analysed using one-way anova and Duncan tests (α = 0.05).


Colour differences between baseline and sealer staining were in the range of 8.1–9.9, but differences between the groups were not significant. After bleaching, the degree of lightening was essentially identical for the carbamide peroxide and sodium perborate + carbamide peroxide groups, but was significantly greater (P < 0.05) in these two groups than in the sodium perborate + water group.


For bleaching AH26 sealer-stained teeth, carbamide peroxide gel and carbamide peroxide gel mixed with sodium perborate were equally effective and significantly better than sodium perborate mixed with water.