不同pH值过氧化氢对人牙本质颜色、透明度和激光诱导荧光的影响

Effect of hydrogen peroxide with different pH values on the color, translucency and laser-induced fluorescence of human dentin

目的研究不同pH值30％过氧化氢对人牙本质颜色、透明度和激光诱导荧光的影响，探究30％过氧化氢对牙本质的漂白机制。方法从60颗人下颌第三磨牙冠部取得牙本质样本，按随机化数字表随机分成4组（每组15颗）：酸性、中性、碱性30％过氧化氢组（简称漂白组，pH值分别为3．4、7．0、9．0）以及对照组（去离子水）。使用相应过氧化氢溶液分别对3组进行漂白处理，每次0．5h，共4次；对照组不进行漂白处理。在基线（0h）和处理时间分别为0．5、1．0和2．0h时，根据国际照明委员会（Commission Internationale Ed I’eclairage，CIE）L”a‘b。色彩系统（L‘为明度，a＊为红绿色品，b＊为黄蓝色品），以色度计（ShadeEyeNCC）测量牙本质样本在白、黑、黄三种背景下的L”、a‘和b‘值，得出牙本质透明度系数（translucency parameter，TP）、遮盖效应、彩度和白度。用拉曼光谱仪测量牙本质拉曼光谱，得出激光诱导荧光强度（1aser—induced fluorescence intensity，FI）及其比例值（FI％）。计算上述指标3个时间点与基线的差值（即△值）。使用重复测量方差分析比较差异。结果2h时酸性、中性、碱性30％过氧化氢组的△兀分别为9960．03±2037．74、8502．09±1413．86、8554．29±1986．19；AFI％分别为84．60±3．43、84．89±5．19、86．72±2．65。漂白组各指标均受时间因素影响（P〈0．001），相同时间点漂白组ATP、A彩度、△白度、△L。、△a。、△b”、△E、△FI和AFI％与对照组差异均有统计学意义（P〈0．001）；而相同时间点各漂白组GTP、A遮盖效应、△彩度、△白度、△L‘、△b‘、△E、△FI和AFI％间差异均无统计学意义（P〉0．05）。基线水平的FI与彩度（r=-0．4l，P=0．001）、a（r=0．48，P=0．000）、b“（r=-0．41，P=0．001）和白度（r=-0．38，P=0．003）有相关性；△FI与△遮盖效应（r=-0．50，P=0．000）、△TP（r=-0．29，P=0．001）、△彩度（r=-0．28，P=0．001）、△白度（r=-0．34，P：0．000）、△b。（r=-0．28，P=0．001）和△E（r=-0．28，P=0．001）有相关性。结论不同pH值30％过氧化氢均可改变人牙本质的颜色、透明度和激光诱导荧光，其漂白效果无差异。激光诱导荧光的变化与颜色和透明度的变化相关，激光诱导荧光可作为探索牙本质漂白机制的新途径。

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 A FI of acidic, neutral, alkaline 30% HP at 2 h were 9960. 03 ± 2037.74, 8502.09 ± 1413.86, 8554. 29 ± 1986. 19. And AFI% 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 A TP, A chroma, A whiteness, AL＊, ~a＊, Ab＊, AE, AFI and AFI% （P 〈 O. 001 ）. There was no significant difference between three bleaching groups on ATP, Amasking effects, Achroma, Awhiteness, AL＊, Ab~, AE, AFI and A FI%. Correlation analysis demonstrated that FI was associated with chroma, a＊, b＊ and whiteness, respectively, and AFI was associated with ATP, Amasking effects, Awhiteness, Achroma, Ab＊ and AE. 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.