Effect of hydrogen peroxide with different pH values on the color, translucency and laser-induced fluorescence of human dentin / 中华口腔医学杂志

ABSTRACT

<p><b>OBJECTIVE</b>To investigate the effect of 30% hydrogen peroxide(HP) with different pH values on color, translucency and laser-induced fluorescence of human dentin.</p><p><b>METHODS</b>Sixty dentin specimens from crown of mandibular third molars were randomly assigned into four groups (n = 15) and treated with acidic 30% HP, neutral 30% HP, alkaline 30% HP and deionized water (control group), respectively. The bleaching process was 0.5 h×4 times, and time points for measuring were baseline (0), 0.5, 1 and 2 h. A colorimeter was employed to measure the L(*), a(*), b(*) coordinates of dentin against white, black and yellow background. Then the parameters of translucency, masking effects, chroma and whiteness were calculated. The dentinal laser-induced Raman/fluorescence spectra was recorded by a Raman spectrometer and the fluorescence intensity(FI) and FI% were calculated.</p><p><b>RESULTS</b>&Delta;FI of acidic, neutral, alkaline 30% HP at 2 h were 9960.03 ± 2037.74, 8502.09 ± 1413.86, 8554.29 ± 1986.19. And &Delta;FI% were 84.60 ± 3.43, 84.89 ± 5.19, 86.72 ± 2.65, respectively. Repeated measure of ANOVA revealed that all parameters in the bleaching groups were significantly influenced by time (P < 0.001). Compared with control group, bleaching resulted significant change of &Delta;TP, &Delta;chroma, &Delta;whiteness, &Delta;L(*), &Delta;a(*), &Delta;b(*), &Delta;E, &Delta;FI and &Delta;FI% (P < 0.001). There was no significant difference between three bleaching groups on &Delta;TP, &Delta;masking effects, &Delta;chroma, &Delta;whiteness, &Delta;L(*), &Delta;b(*), &Delta;E, &Delta;FI and &Delta;FI%. Correlation analysis demonstrated that FI was associated with chroma, a(*), b(*) and whiteness, respectively, and &Delta;FI was associated with &Delta;TP, &Delta;masking effects, &Delta;whiteness, &Delta;chroma, &Delta;b(*) and &Delta;E.</p><p><b>CONCLUSIONS</b>30% HP with different pH values could result in the same change of the color, translucency and laser-induced fluorescence of human dentin.Laser-induced fluorescence was associated with dentinal color and translucency, which might be a novel way to investigate the bleaching mechanism of dentin.</p>