A Pilot Study About the Effect of Laser-Induced Fluorescence on Color and Translucency of Human Enamel During Tooth Bleaching

Abstract

Objective:

To probe into the effect of laser-induced fluorescence (LIF) on color and translucency of human enamel during tooth bleaching.

Materials and methods:

Twenty enamel slabs were randomly assigned to be whitened by acidic 30% hydrogen peroxide (HP), neutral 30% HP, alkaline 30% HP, and distilled water, respectively, monitored by a colorimeter and Raman spectrometer simultaneously. Afterward, the parameter differences of color, translucency, Raman relative intensity, and LIF intensity between baseline and post-treatment of each bleaching cycle were calculated.

Results:

The results demonstrated that the three bleaching groups resulted in increasingly prominent whitening outcome over time compared with control group, and no statistical difference was detected between them. Accordingly, the bleaching groups also engendered a same decrease tendency in fluorescence intensity (FI). However, less demineralization effect occurred on the enamel surface in neutral HP group. The correlation analysis further excluded the effect of demineralization on all the optical parameters (p > 0.05). Besides, various degrees of dependency were detected between FI and translucency parameter (TP), masking effect (ME), C*ab, W*, b*. In addition, ΔFI was associated with parameters of ΔC*ab, ΔW*, Δb*, ΔE, Δa*, and ΔME. ΔFI% was correlated with ΔC*ab, Δb*, ΔW*, and ΔE values.

Conclusions:

Thirty percent HP with different pH values could result in same variation tendency of enamel color, translucency, and FI. Plus, FI showed a strong association with enamel color and translucency alteration, which is promising for future application as a nondestructive testing method to evaluate bleaching effect and might be a novel way to investigate tooth bleaching mechanism.