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. Delta Eab*, Delta E00, and Delta WID were calculated between sequential evaluation timepoints and between baseline and each evaluation timepoint. Color coordinates and WID differences in each timepoint and technique were analyzed by Wilcoxon Signed Rank, Kruskal-Wallis and Mann-Whitney U test, respectively. Delta Eab*, Delta E00, and Delta WID were interpreted by color visual thresholds. Results The techniques presented a significant increase in L* and WID and, a significant decrease in a* and b* until the completion of treatments. Statistical differences between the techniques for a*, b* and WID were observed from T1 until T3. All techniques demonstrated excellent effectiveness for Delta Eab*, Delta E00, and Delta WID 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.