Comparative study of the effectiveness of different bleaching agents on blood-colored extracted teeth and investigation of recoloring after bleaching: an in vitro experimental study.

Objectives: This study evaluated the efficacy of three distinct bleaching agents over time on blood-stained, devitalized teeth. Furthermore, the recoloring subsequent to bleaching will be monitored. Methods: The study was conducted on 60 caries-free, unfilled, upper human incisors. The Freccia and Peters blood staining technique was employed, and four groups (n = 15) were identified: control, 35% hydrogen peroxide-treated, 37% carbamide peroxide-treated, and sodium perborate-treated groups. Color differences were measured using ΔE00, ΔWID, L*, a*, and b* values. To investigate tooth discoloration after bleaching, 10 unbleached teeth with three groups of 10 bleached teeth were compared by vine staining. The group of bleached teeth was restored immediately, another group waited one week, and the third group had sodium ascorbate applied and analyzed using one-way analysis of variance tests (p < 0.05). Results: Among the groups, carbamide peroxide exhibited the most significant whitening during the 6-day bleaching process, followed by hydrogen peroxide and sodium perborate. Subsequent examination of the wine recoloring of post-bleaching samples demonstrated that bleached teeth exhibited a heightened propensity for recoloration in contrast to unbleached teeth. Notably, sodium ascorbate treatments for hydrogen peroxide neutralization and the wait-and-restore approach were not statistically significant in terms of preventing recoloration. Conclusions: Sodium perborate is less effective and more time-consuming than hydrogen peroxide or carbamide peroxide for bleaching purposes. Carbamide peroxide is the most effective bleaching agent. The sodium ascorbate treatment and the wait-and-restore approach are ineffective in preventing recoloring. Bleached teeth have more discoloration than unbleached teeth.