PERMEABILITY CHARACTERISTICS OF DENTIN

牙本质代表活的、敏感的、多孔的矿化隔室 它将牙齿中形成的空洞与下面的牙齿分开 果肉。牙本质的渗透性特征是 了解牙本质敏感性和牙髓对牙本质的反应 程序或材料。牙髓的很多刺激性空洞 这可能是由于牙本质上的液体移动引起的 切割过程中的热刺激或蒸发刺激。拟议中的实验 旨在测量这些流体位移的大小，并减少 它们可以归结为一个公分母，一种物理力(厘米H2O)。一次 确定后，这些力将应用于空洞以确定 所需的临界物理力(负静水压) 在正常犬牙本质和牙本质中产生成牙本质细胞移位 用一种破坏成牙本质细胞微管的药物治疗。作为以下内容的一部分 对空洞准备的反应可能是由于神经源性炎症， 我们还计划测量牙本质液的自发流动率， 神经性牙髓压力(PP)和牙髓血流量(PBF) 正常窝洞准备后失神经犬牙检查 神经刺激对这些变量的影响。在另一组 实验中，PP和PBF将使用两者进行药理学操作 血管扩张剂和血管收缩药，以确定它们如何影响液体 转移到牙本质上。最后，牙本质液会被身体强迫 通过牙本质(当牙冠就位时可能发生的)来确定什么 PP和PBF也是如此。 牙髓准备后出现的一些牙髓刺激可能是 由于毛细管力作用于干牙本质。我们会比较牙髓 犬牙对正常窝洞制剂的反应，对已完成的 牙本质残留在生理盐水中是无损伤的 这将防止毛细管力的表达。其他牙齿也会 受到轻微的热刺激和化学刺激 目的。 将在体外进行一系列实验，试图将 牙本质具有优良的涂抹层或粘接树脂，以防止液体 从发生的转变。然后，最好的密封方法将用于 狗牙在体内防止液体引起的牙髓刺激。贯穿始终 在授权期内，我们收集的数据将用于制定一系列 水力传导性、扩散性和导水率的数学表达式 向外对流流体运动对向内扩散的相互作用 有没有涂抹层。这将允许 牙本质和牙本质复合体的计算机模拟研究进展 这对世界各地的许多实验室应该是非常有用的。 总体而言，这些实验应该会提供急需的信息 关于空洞准备对牙髓牙本质复合体的影响。 结果将使我们能够就以下方面提出一系列建议 临床医生如何保护牙髓并避免牙髓刺激。

Dentin represents the living, sensitive, porous mineralized compartment that separates cavities prepared in teeth from the underlying dental pulp. The permeability characteristics of dentin are central to understanding dentin sensitivity and pulpal reactions to dental procedures or materials. Much of the pulpal irritation of cavity preparation is probably due to fluid shifts across dentin caused by thermal or evaporation stimuli during cutting. The proposed experiments are designed to measure the magnitude of these fluid shifts and reduce them to a common denominator, a physical force (cm H2O). Once identified, these forces will be applied to cavities to determine the critical physical force (negative hydrostatic pressure) necessary to produce odontoblast displacement in normal dog dentin and in dentin treated with a drug which disrupts odontoblast microtubules. As part of the reaction to cavity preparation may be due to neurogenic inflammation, we also plan to measure the spontaneous rate of dentinal fluid flow, pulpal pressure (PP) and pulpal blood flow (PBF) in innervated versus denervated dog teeth following normal cavity preparation to examine the influence of nerve stimulation on these variables. In another set of experiments, PP and PBF will be manipulated pharmacologically using both vasodilators and vasconstrictors, to determine how they influence fluid shifts across dentin. Finally, dentinal fluid will be physically forced across dentin (as may occur when crowns are seated) to determine what that does to PP and PBF. Some of the pulpal irritation seen following cavity preparation may be due to capillary forces acting on dry dentin. We will compare pulpal reactions to normal cavity preparations in dog teeth, to that done atraumatically in teeth were the dentin remains under saline solution that will prevent the expression of capillary forces. Other teeth will be subjected to mild thermal and chemical irritation for comparative purposes. A series of experiments will be done in vitro in an attempt to seal dentin with superior smear layers or adhesive resins to prevent fluid shifts from occurring. The best method of sealing will then be used in dog teeth in vivo to prevent fluid-induced pulpal irritation. Throughout the grant period, the data we collect will be used to develop a series of mathematical expressions of hydraulic conductance, diffusion and the interaction of outward convective fluid movement on inward diffusion in the presence or absence of smear layers. This will permit the development of computer simulations of dentin and the pulpodentin complex which should be extremely useful to many laboratories around the world. Overall, these experiments should provide much needed information regarding the effects of cavity preparation on the pulpodentin complex. The results will permit us to make a series of recommendations regarding how clinicians can protect the pulp and avoid pulpal irritation.