Effectiveness and one-year whiteness stability of different in-office bleaching agents and alternative protocols

Statement of problem. In-office bleaching has been widely researched. However, few studies have evaluated alternative protocols for this procedure. Moreover, information on the long-term stability of in-office whitening is limited. Purpose. The purpose of this in vitro study was to evaluate the effectiveness and 1-year stability of in-office bleaching with 35% hydrogen peroxide (35%HP) and 37% carbamide peroxide (37%CP) using traditional and alternative protocols. Material and methods. Forty human third molars were stained with tea and allocated to groups (n=10). Traditional protocols consisted of 3 applications of 35%HP for 15 minutes and 1 application of 37%CP for 45 minutes. Alternative protocols consisted of 1 application of 35%HP for 45 minutes and 3 applications of 37%CP for 45 minutes. Protocols were applied for 3 weeks. CIELab color coordinates were measured at baseline and weekly during treatment and at 1-week, 6-month, and 1-year follow-ups. Effectiveness and stability of the bleaching treatments were interpreted using 50:50% perceptibility and acceptability thresholds. CIELab, chroma, hue angle, and whiteness index were analyzed using the Wilcoxon signed-rank test (alpha=.05). Results. All protocols showed improvement in bleaching after the first week (P <=.005). All bleaching procedures presented excellent whitening outcomes. Alternative protocols showed a larger rebound effect after 1 year, indicating less stability. For the whiteness index, no differences between the completion of the treatments and 1-year follow-up was found for the bleaching treatments and protocols (P>.05), except for the 37%CP alternative protocol (P=.005). Conclusions. All tested protocols presented excellent effectiveness in bleaching. Traditional protocols exhibited a greater whiteness stability, while the alternative protocols showed a greater rebound effect after 1 year.