[Effect of hydrogen peroxide with different pH values on the color, translucency and laser-induced fluorescence of human dentin].
OBJECTIVE
To investigate the effect of 30% hydrogen peroxide(HP) with different pH values on color, translucency and laser-induced fluorescence of human dentin.


METHODS
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.


RESULTS
ΔFI of acidic, neutral, alkaline 30% HP at 2 h were 9960.03 ± 2037.74, 8502.09 ± 1413.86, 8554.29 ± 1986.19. And ΔFI% 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 ΔTP, Δchroma, Δwhiteness, ΔL(*), Δa(*), Δb(*), ΔE, ΔFI and ΔFI% (P < 0.001). There was no significant difference between three bleaching groups on ΔTP, Δmasking effects, Δchroma, Δwhiteness, ΔL(*), Δb(*), ΔE, ΔFI and ΔFI%. Correlation analysis demonstrated that FI was associated with chroma, a(*), b(*) and whiteness, respectively, and ΔFI was associated with ΔTP, Δmasking effects, Δwhiteness, Δchroma, Δb(*) and ΔE.


CONCLUSIONS
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.
State Key Laboratory Breeding Base of Basic Science of Stomatology & Key Laboratory of Oral Biomedicine Ministry of Education, School of Stomatology, Wuhan University, Wuhan 430079, China.
Shan-shan
SS
Liang
Tao
T
Jiang
Yi-ning
YN
Wang
D003116:Color; D003124:Colorimetry / Q000379:methods; D003442:Crowns; D003804:Dentin / Q000033:anatomy & histology / Q000187:drug effects*; D005453:Fluorescence; D006801:Humans; D006861:Hydrogen Peroxide / Q000737:chemistry / Q000494:pharmacology*; D006863:Hydrogen-Ion Concentration; D008964:Molar, Third; D011897:Random Allocation; D013059:Spectrum Analysis, Raman; D014073:Tooth Bleaching / Q000379:methods; D058205:Tooth Bleaching Agents / Q000737:chemistry / Q000494:pharmacology*
D058205:Tooth Bleaching Agents; D006861:Hydrogen Peroxide