Role of Water in Dental Hard Tissues

摘要 水是牙齿硬组织的三大成分之一，但水的结构和如何 在牙齿形成、退化和损伤过程中，水与牙齿硬组织中的其他成分相互作用。 目前仍不清楚。核磁共振法和红外吸收法是可以 直接探测生物组织中的水。然而，它们的性能是有限的，因为只有核磁共振 测量样本的平均效果，而IR需要对牙齿等组织进行特殊准备，并可以 改变组织的属性。最近，我们证明了荧光压缩拉曼光谱 具有探测牙齿硬组织中水的能力，并表明水的光谱剖面是 牙本质和牙釉质是截然不同的。在不同的测试中，即使在牙釉质中，轮廓也是不同的 斑点。这些结果表明，拉曼光谱学可能提供了关于 牙齿硬组织中的水，以及可能影响对牙齿发病机制的理解的细节 有问题。拟议项目的主要目标是使用拉曼光谱来识别 牙齿硬组织中水分含量和结构的变化可能与牙齿组织相关 病理学。AIM 1将确定最佳可用的拉曼光谱配置 探测牙体硬组织中的水分含量。三种常见的荧光抑制方法，即， 结合InGaAs探测器、紫外共振拉曼光谱和时间选通拉曼光谱的近红外激发 将进行比较以确定与水相关的拉曼信号的信噪比如何 最大限度地增强了。我们希望将系统灵敏度提高一个数量级或更多。目标2将 研究拉曼光谱反映的水量变化和结构变化 并确定这些变化是否与牙齿硬组织中的其他化学/物理变化相关 纸巾。有不同程度脱矿和有机物分解的牙齿将准备展示 不同程度的化学成分变化。将从这些模拟样品中获取拉曼光谱 并用于探测自然发育的龋齿的成分变化。拉曼 光谱学还将与微机械测试相结合，以确定水与水之间的相关性 成分和组织发生变化，力学性能发生变化。

Summary Water is one of the three major constituents of dental hard tissues, but the structure of water and how water interacts with other components in dental hard tissues during teeth formation, degradation, and lesion remain unclear. Nuclear magnetic spectrometry (NMR) and infrared absorption (IR) are the methods that can directly probe water from biological tissues. However, their performances are limited because NMR only measures the average effect of the sample, while IR requires special preparations to tissues like teeth and could alter the properties of the tissues. Recently, we demonstrated that fluorescence compressed Raman spectroscopy has the capability of probing water in dental hard tissues and showed that the spectral profiles of water are dramatically different between dentin and enamel. The profiles varied even within enamel at different testing spots. Those results indicate that Raman spectroscopy may provide additional information about the role of water in dental hard tissues with details that may impact the understanding of the mechanisms of dental problems. The major aim of the proposed project is to use Raman spectroscopy to identify how the changes in water content and structure in dental hard tissues may correlate with dental tissue pathologies. Aim 1 will determine the best available Raman spectroscopy configurations for probing water contents in dental hard tissues. Three common fluorescence suppression approaches, i.e., near-infrared excitation combining InGaAs detector, UV resonance Raman, and time-gated Raman spectroscopy will be compared to determine how the signal to noise ratio of the water-related Raman signals can be maximumly enhanced. We expect to increase the system sensitivity by one order or more. Aim 2 will investigate the changes in water amount and structure changes reflected by Raman spectroscopy and identify if these changes are correlated with other chemical/physical changes in dental hard tissues. Teeth with various degrees of demineralization and decomposing of organics will be prepared to show deferent levels of chemical compositional changes. Raman spectra will be acquired from these simulated samples and used as references for probing compositional variations in teeth with naturally developed caries. Raman spectroscopy will also be combined with micro-mechanical testing to identify correlations between water contents and structure change and mechanical property changes.