RESUMO
Background and objective: The aim of this study is to compare the bleaching effect of photon-induced photoacoustic streaming (PIPS) using carbamide peroxide or sodium perborate-20% hydrogen peroxide (H2O2) compared with walking-bleaching techniques using sodium perborate-20% H2O2 or carbamide peroxide without PIPS on artificially colored teeth. Materials and methods: Root canal treatments of 85 extracted human maxillary central incisors were completed and artificially stained using sheep's blood. Teeth were randomly grouped into five groups according to the bleaching techniques to be tested: Group 1: walking bleaching with carbamide peroxide; Group 2: walking bleaching with sodium perborate-20% H2O2; Group 3: PIPS+carbamide peroxide; Group 4: PIPS+sodium perborate-20% H2O2; and Group 5: control. Experimental specimens were bleached for 3 weeks. Buccal surfaces of the crowns were used for spectrophotometric measurements, limited with a 7-mm external diameter rounded strip, before bleaching and on days 7, 14, and 21. The total change in color (ΔE*) were analyzed with Welch's ANOVA at a significance level of p = 0.05 and Tamhane post-hoc test was used for multiple comparisons. Results: Starting from the second week, Group 4 showed significantly better bleaching effect compared with the other groups (p < 0.05). The other experimental groups also have bleaching effects, but there was no statistically significant difference between Group 1, Group 2, and Group 3 (p > 0.05). Conclusions: Sodium perborate-20% H2O2 activated with PIPS gave a bleaching effect superior to that of walking-bleaching techniques or PIPS using with carbamide peroxide.
