1 The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) and Key Laboratory of Oral Biomedicine Ministry of Education, School and Hospital of Stomatology, Wuhan University, Wuhan, China.
2 Department of Prosthodontics, Hospital of Stomatology, Wuhan University, Wuhan, China.
J Dent Res. 2018 Nov;97(12):1339-1345. doi: 10.1177/0022034518784260. Epub 2018 Jun 25.
Recent studies suggested that bleaching agents may whiten teeth by oxidizing the fluorescent materials, which are the proteins located in the organic-inorganic interface. Therefore, we postulated that fluorescence of dentin came from dentin phosphoprotein (DPP) and that bleaching agents might bleach dentin by oxidizing DPP. Fifty-six specimens were randomly divided into 4 groups and exposed to distilled water, hydrogen peroxide (HP), ethylenediamine tetraacetic acid disodium salt (EDTA), and acetic acid for 24 h. After measuring the organic and inorganic components, fluorescence, and color characteristics of dentin before and after exposure, we found that when DPP was removed from dentin by EDTA, fluorescent intensity declined proportionally with the reduction in Raman relative intensity, and dentin was whitened considerably, with an Δ E value 6 times higher than that of the distilled water group. On the contrary, due to the incapability of acetic acid to dissolve DPP during decalcification, fluorescent intensity values and tooth color remained nearly unchanged after exposure to acetic acid. Dentin exposed to neutral HP showed no obvious morphologic and organic/inorganic component changes except for the destruction of DPP. Similarly, dramatically decreased fluorescent intensity and lightened color were found in the HP group. Moreover, DPP solution of the HP group exhibited decreased ultraviolet absorbance, especially between 250 and 300 nm, which arose from aromatic amino acids. The results indicated that DPP was responsible for the fluorescent properties of dentin and that HP might bleach dentin by the oxidization of aromatic amino acids in DPP. These findings are of great significance in promoting our further understanding of the mechanism of tooth bleaching and the fluorescent property of normal dentin.
近期研究表明，漂白剂可能通过氧化位于有机-无机界面处的荧光物质来使牙齿变白。因此，我们推测牙本质的荧光来自牙本质磷蛋白（DPP），并且漂白剂可能通过氧化 DPP 来漂白牙本质。将 56 个样本随机分为 4 组，分别用蒸馏水、过氧化氢（HP）、乙二胺四乙酸二钠盐（EDTA）和乙酸处理 24 小时。在测量牙本质暴露前后的有机和无机成分、荧光和颜色特性后，我们发现，当 EDTA 从牙本质中去除 DPP 时，荧光强度与拉曼相对强度的降低成正比，牙本质明显变白，ΔE 值比蒸馏水组高 6 倍。相反，由于在脱矿过程中乙酸不能溶解 DPP，因此暴露于乙酸后的荧光强度值和牙齿颜色几乎保持不变。中性 HP 处理的牙本质除了 DPP 破坏外，形态和有机/无机成分均无明显变化。同样，在 HP 组中，也发现了荧光强度显著降低和颜色变浅。此外，HP 组的 DPP 溶液的紫外吸收减弱，尤其是在 250nm 到 300nm 之间，这是由于芳香族氨基酸的存在。结果表明，DPP 是牙本质荧光特性的原因，而 HP 可能通过氧化 DPP 中的芳香族氨基酸来漂白牙本质。这些发现对促进我们进一步了解牙齿漂白的机制和正常牙本质的荧光特性具有重要意义。
