Effectiveness and Stability of In-Office Bleaching Agents and Protocols

Objectives: The aim of this study was to evaluate the effectiveness and stability of two in-office bleaching agents using different protocols.
Methods: Forty third humans molars were prepared and stained with black tea. After randomization, the teeth were allocated in groups (n=10) according to the bleaching agents and protocols: hydrogen peroxide 35% (HP) and carbamide peroxide 37% (CP), tradicional and alternative protocols. The tradicional protocols consisted of 3 applications of 15 minutes (HP) and 1 application of 45 minutes (CP), and the alternative protocols in 1 application of 45 minutes and 3 applications of 45 minutes per session to HP and CP, respectively, for three consecutive weeks. The color measurements were conducted at baseline (T0) and weekly (T1, T2 and T3), until treatment was completed, and again at one-week (T4), six-month (T5) and twelve-month follow-ups (T6). Color differences and whiteness index for dentistry were calculated by CIEDE2000 and WI_D formulas, according to each evaluation period and baseline. The mean values for ΔE₀₀, ΔWI_D, ΔL*, Δa* and Δb* were submitted to two-way ANOVA and Bonferroni post-hoc tests.
Results: Significant differences were observed between the evaluation timepoints (p≤0.035). Significant differences between bleaching protocols were found only for ΔL* (p=0.017). The interaction between bleaching protocols and evaluation timepoints was not significant (p≥0.174). All the bleaching agents and protocols presented ΔE₀₀ and ΔWI_D above the perceptibility and acceptability interpretation thresholds adopted for whitening-depended color differences (ΔE₀₀>5.4 and ΔWI_D>2.6), except for ΔWI_D - tradicional protocol with carbamide peroxide at T1, T3 and T6 evaluation timepoints.
Conclusions: Regarding color variation all bleaching agents and protocols presented similar bleaching effectiveness and stability at six-month and twelve-month follow-ups. Therefore, the characteristics of each protocol and clinical situation should be considered when rendering the adequate treatment choice.