Related Experiment Video
Updated: May 21, 2026
An In Vitro Approach to Photodynamic Therapy
Published on: August 17, 2018
Effects of phthalimidoperoxycaproic acid (PAP+) associated or not with LED irradiation as a bleaching agent: an in
Samuel da Silva Palandi1, Marcos Roberto de Lima Benati1, Beatriz de Cássia Romano1
1Department of Restorative Dentistry, State University of Campinas, Campinas, Brazil.
Objective:
To evaluate the efficacy and safety of phthalimidoperoxycaproic acid (PAP+) as a bleaching agent, combined or not with blue or violet LEDs.
Materials And Methods:
108 sound bovine enamel/dentin blocks stained with black tea were assigned to nine groups (n = 12): Control (no treatment - NC); MMO (Bright max violet LED, MMOptics); VIO (VIO405, HiSmile); PAP (PAP+ - VIO405 whitening kit, HiSmile); PAP/MMO; PAP/VIO; HP10 (10% Hydrogen Peroxide - White Class 10%, FGM); HP10/MMO; HP10/VIO. LED irradiation and light potency were analyzed, and the pH of the gels was assessed before and after treatment. Afterwards, dental blocks underwent treatment for 7 days according to each protocol. Samples were assessed for color change (ΔE00), whiteness index (ΔWID), microhardness analysis and enamel morphology (SEM). Data were analyzed by two-way ANOVA and Tukey or Bonferroni post-hoc test (α = 0.05), and Linear Mixed Models and Tukey-Kramer (α = 0.05).
Results:
VIO delivered approximately 10% of MMO irradiance. Irradiation reduced gel pH, but values remained above 5.8. PAP did not differ from controls, regardless of LED use (p > 0.05), whereas HP10 showed greater bleaching efficacy, especially when combined with MMO (p < 0.05). No morphological enamel damage was observed, and microhardness increased over time in all groups (p < 0.05).
Conclusion:
VIO exhibited lower power and stability than MMO, but arguably, both enhanced the efficacy of HP10. Under the tested protocol, PAP+ failed to induce significant bleaching, regardless of association to LED irradiation, while HP10 effectively induced bleaching independently of LED association. Importantly, none of the tested treatments resulted in microhardness loss or morphological damage to the enamel surface.
Clinical Relevance:
PAP + was not able to promote significant bleaching in the adopted protocol, showing mostly similarities to the NC group, and did not improve the LED devices efficacy. PH10 consistently showed significant bleaching, benefiting from the association with MMO. MMO alone was able to produce light bleaching effects.
