Continuous vs fractionated violet LED light protocols for dental bleaching: Evaluations of color change and temperature of the dental pulp and buccal surface

Abstract

Background: Dental color change and the temperature of the pulp chamber and of the buccal surface were evaluated during bleaching with 37% carbamide peroxide (CP) with continuous vs fractionated violet LED light protocols.

Methodology: Bovine incisors received in-office bleaching for 30 min using different light protocols (Bright Max Whitening, MMOptics). Teeth were separated into groups (n = 10): HP) 35% hydrogen peroxide (Whiteness HP, FGM)/no light; CP) 37% carbamide peroxide (Whiteness SuperEndo, FGM)/no light; CP10) CP+10 min of continuous light; CP20) CP+20 min of continuous light; CP30) CP+30 min of continuous light; CPF) CP+20 cycles of 60 s light / 30 s no light (fractionated). Color evaluations were performed at different times. Evaluations of pulp and buccal surface temperatures were performed before and throughout the 30 min of bleaching.

Results: Generalized linear models for repeated measures over time were applied to the data (α=5%). After the 1st session, CP20 and CP30 had significantly lower b* values ​​than CP and CP10 (p = 0.0071). For ΔE_ab and ΔE₀₀, CPF, CP20 and CP30 showed the highest color change among the treatments after the third bleaching (p<0.05). For temperature evaluations, CP30 showed higher pulp and buccal surface temperatures than the other protocols (p<0.0001) after 20 min.

Conclusion: Fractionated or continuous application of violet LED for 20 or 30 min leads to greater effectiveness of color change. All protocols with the application of LED led to an increase in pulp and buccal surface temperatures during bleaching, although the fractionated application appeared to be safer than the use of continuous light.

Keywords: Carbamide peroxide; Color; Dental bleaching; Hydrogen peroxide; Pulp temperature; Violet light.