Severcan Feride, Gokduman Kurtulus, Dogan Ayca, Bolay Sukran, Gokalp Saadet
Department of Biology, Middle East Technical University, 06531 Ankara, Turkey.
Appl Spectrosc. 2008 Nov;62(11):1274-9. doi: 10.1366/000370208786401554.
In-office and at-home bleaching techniques are widely used methods for the whitening of teeth. However, the safety of these techniques has not been clarified yet. The aim of the current study is to investigate the in-office- and at-home-bleaching-induced structural and quantitative changes in human enamel and dentin at the molecular level, under in vitro conditions. The Fourier transform mid-infrared (mid-FT-IR) spectroscopic technique was used to monitor bleaching-induced structural changes. Band frequency and intensity values of major absorptions such as amide A, amide I, phosphate (PO(4)), and carbonate (CO(3)(-2)) bands, for treatment groups and control, were measured and compared. The results revealed that both procedures have negligible effects on dentin constituents. In office-bleached enamel, in addition to demineralization, a decrease in protein and polysaccharide concentrations, mineral-to-protein ratio, and the strength of hydrogen bonds around NH groups, as well as a change in protein secondary structure were observed. The protein structure changed from beta-sheet to random coil, which is an indication of protein denaturation. However, no significant variations were observed for at-home bleached enamel. The control, at-home, and in-office bleached enamel samples were differentiated with a high accuracy using cluster analysis based on FT-IR data. This study revealed that office bleaching caused deleterious alterations in the composition and structure of enamel that significantly affected the crystallinity and mineralization of the tissue. Therefore, at-home bleaching seems to be much safer than in-office bleaching in terms of molecular variations.
诊室和家庭牙齿美白技术是广泛应用的牙齿美白方法。然而，这些技术的安全性尚未明确。本研究的目的是在体外条件下，从分子水平研究诊室和家庭牙齿美白对人牙釉质和牙本质结构及定量的影响。采用傅里叶变换中红外（mid-FT-IR）光谱技术监测美白引起的结构变化。测量并比较了治疗组和对照组中酰胺A、酰胺I、磷酸盐（PO(4)）和碳酸盐（CO(3)(-2)）等主要吸收峰的谱带频率和强度值。结果表明，两种方法对牙本质成分的影响均可忽略不计。在诊室美白的牙釉质中，除了脱矿外，还观察到蛋白质和多糖浓度降低、矿物质与蛋白质的比例降低、NH基团周围氢键强度降低以及蛋白质二级结构发生变化。蛋白质结构从β折叠变为无规卷曲，这表明蛋白质发生了变性。然而，家庭美白的牙釉质未观察到明显变化。基于FT-IR数据，通过聚类分析能够高精度地区分对照组、家庭美白组和诊室美白组的牙釉质样本。本研究表明，诊室美白会对牙釉质的组成和结构造成有害改变，显著影响组织的结晶度和矿化程度。因此，就分子变化而言，家庭美白似乎比诊室美白安全得多。
