Effectiveness and color stability of bleaching techniques on blood-stained teeth: An in vitro study.

OBJECTIVE: Evaluate the effectiveness and color stability of bleaching techniques on blood-stained teeth. MATERIAL AND METHODS: The teeth were stained by blood and allocated to groups: walking bleach, inside/outside, and in-office bleaching. L*, a*, b*, C*, h degrees color coordinates were measured using a clinical spectrophotometer at baseline, weekly (T1-T2-T3), and at 1-week (T4), 6-months (T5), and 1-year (T6) follow-up evaluations. DeltaEab* , DeltaE00 , and DeltaWID were calculated between sequential evaluation timepoints and between baseline and each evaluation timepoint. Color coordinates and WI(D) differences in each timepoint and technique were analyzed by Wilcoxon Signed Rank, Kruskal-Wallis and Mann-Whitney U test, respectively. DeltaEab* , DeltaE00 , and DeltaWID were interpreted by color visual thresholds. RESULTS: The techniques presented a significant increase in L* and WI(D) and, a significant decrease in a* and b* until the completion of treatments. Statistical differences between the techniques for a*, b* and WI(D) were observed from T1 until T3. All techniques demonstrated excellent effectiveness for DeltaEab* , DeltaE00 , and DeltaWID between baseline and each evaluation and follow-up timepoints. However, at T6, it was possible to identify a rebound effect for all techniques. CONCLUSIONS: All bleaching techniques presented excellent effectiveness. The stability of the whitening produced was maintained for 6 months. CLINICAL SIGNIFICANCE: Effective whitening of blood-stained teeth was achieved using walking bleach (sodium perborate), inside/outside (hydrogen peroxide - 7.5%) and in-office techniques (hydrogen peroxide - 35%). The bleaching techniques were effective after the completion of the treatments. A slight rebound was observed at 1 year follow-up.