Effect of light-activation systems associated with whitening pens in the bleaching efficacy and hydrogen peroxide...

To evaluate the bleaching efficacy and hydrogen peroxide (HP) permeability of whitening pens, with and without light-activation systems. Also, pulp temperature and physicochemical properties were assessed, as well as the characterization of the light sources.

Ninety premolars were distributed into nine groups (n = 10): untreated, Colgate Optic White Pen ComfortFit LED (CF), Colgate Optic White Pen Express (CX), Equate Teeth Whitening Kit (EW) and Zimba Teeth Whitening Kit (ZW), with and without light-activation. Bleaching efficacy (WI_D, ΔE_ab, and ΔE₀₀) was assessed using a digital spectrophotometer. HP permeability (μg/mL) was measured by UV-Vis; initial concentration (%), pH, and pulp temperature variation (ΔT, °C) by titration, pH meter, and T-type thermocouple, respectively. Light characteristics were determined using spectroradiometer and integrating sphere. Statistical analysis included ANOVA, Tukey's, and Dunnett's tests (α = 0.05).

ZW light device exhibited the highest power and irradiance (p < 0.05). EW and ZW emitted blue light (peak: 456 nm), while CF device emitted violet light (peak: 405 nm). Light-activation did not significantly impact WI_D or HP permeability (p > 0.05). However, CF and CX showed greater color changes under light, when evaluated by ΔE_ab/ΔE₀₀ (p < 0.05). All groups showed acidic pH; EW and ZW exhibited the highest HP concentration and permeability (p < 0.05). Pulpal temperature variations were not significant across groups (p > 0.05).

Light-activation had no significant impact on bleaching efficacy (WI_D) or HP permeability, regardless of HP concentration or pH.

It is not essential to combine light devices with whitening pens to achieve bleaching efficacy.