Bleaching effect of sodium perborate on discolored pulpless teeth

Objective: The purpose of this study was to evaluate the internal bleaching effect of sodium perborate and compare with sodium perborate mixed with 30% hydrogen peroxide on middle third of stained pulpless teeth. Methods: Forty bovine incisors were divided in four groups (n=10). Three groups were stained by injecting human blood into pulp chamber and all specimens were endodontically treated: G1- Only endodontically treated, G2 - blood stained, G3- blood stained / sodium perborate, G4- blood stained / sodium perborate mixed with 30% hydrogen peroxide. Values of L*, a*, b* and DE were determined by spectrophotometer (Easy shade – Vita – system CIELab) at five moments: before stained (day 1 – baseline) and after stained (days 7, 14, 21 and residual effect- day 28). Results: Data were submitted to descriptive analysis and Tukey tests (5%). The a* means values tended to red (+a*) in G2 while G1, G3 and G4 tended to green (-a*). The b* means values tended to yellow (+b*) in all groups. At he day 1, the L* values showed statistically significant difference between G1/G2, G1/G3, G1/G4 with higher values to G4>G3>G1>G2. However, there were no statistically significant differences between G2/G3/G4. Total color change was clinically significant (DE > 3.3) for all groups. Conclusions: Sodium perborate mixed with 30% hydrogen peroxide is as efficient as the isolated sodium perborate on bleaching blood stained pulpless teeth. During seven days with pastes in the access cavity, it was obtained a meaningful bleaching effect with both the sodium perborate and the sodium perborate mixed with 30% hydrogen peroxide on blood stained pulpless teeth.