Colorimetric evaluation after in-office tooth bleaching with violet LED: 6- and 12-month follow-ups of a randomized clinical trial

Abstract

Objectives: To evaluate the long-term outcomes of in-office bleaching with violet LED light (LED) alone or combined with carbamide (CP) or hydrogen (HP) peroxides.

Methods: Volunteers of a previous short-term study were recalled for 6- and 12-month follow-ups, according to the following interventions (n = 18/group): LED, CP, LED/CP, HP, and LED/HP. The objective color (ΔE_ab, ΔE₀₀) and whiteness index (ΔWI_D) changes were calculated applying the CIELab coordinates' values obtained using a spectrophotometer. A visual shade guide determined the tooth's subjective color change (ΔSGU). Data were submitted to one-way ANOVA or Welch's ANOVA, following appropriate post hoc tests (α = 5%).

Results: The LED and CP groups exhibited the lowest ΔE_ab, ΔE₀₀, and ΔSGU (p < 0.05), but the LED group displayed a significantly lower ΔWI_D. After 12 months, the LED/CP group presented a higher ΔE_ab and ΔE₀₀ than the CP group (p < 0.05). ΔE_ab, ΔE₀₀, ΔSGU, or ΔWI_D means did not differ statistically between the LED/CP and HP groups. The LED/HP group presented a higher ΔE₀₀ than the HP group, regardless of the time.

Conclusions: The bleaching efficacy of LED alone was significantly lower compared to the LED/CP and HP-containing protocols. After 12 months, the LED/CP and HP groups did not differ in bleaching efficacy. LED irradiation only increased the objective color change of bleaching gels.

Clinical relevance: LED alone promoted a long-term perceptible bleaching, but not compatible with that of high-concentrated HP. The bleaching outcomes of violet irradiation to 37% CP were maintained over time, with LED/CP demonstrating comparable results to HP even after 12 months.

National clinical trials registry (rebec): RBR-5t6bd9.

Keywords: Carbamide peroxide; Follow-up; Hydrogen peroxide; Light; Tooth bleaching.