Spectrophotometric analysis of internal dental bleaching using carbamide peroxide

Objective: The purpose of this study was to evaluate the internal bleaching effect of carbamide peroxide on middle third of stained pulpless teeth. Methods: Forty bovine incisors were divided in four groups (n=10). Two groups were stained by injecting human blood into pulp chamber and all specimens were endodontically treated and subdivided into four groups: G1- only endodontically treated, G2- blood stained, G3- carbamide peroxide, G4- blood stained / carbamide 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 day 1, the L* values showed significantly difference between G1/G2, G1/G4, G3/G2, G3/G4. However, there were no statistically significant differences between G1/G3 and G2/G4. At days 7 and 14, there were no statistically significant differences between G1/G3/G4. At days 21 and 28, there were significantly differences between G1/G4. Total color change was clinically significant (DE > 3.3) for all groups and there were statistically significant differences between G2/G4. Conclusions: The internal bleaching effect of carbamide peroxide was similar to pulpless teeth and artificially blood stained pulpless teeth. It's necessary at least seven days to teeth color stabilization after total remove bleaching agent.