PERMEABILITY CHARACTERISTICS OF DENTIN

几乎所有的牙齿修复体都放置在牙本质上，上面覆盖着一层 微晶碎屑层--即所谓的“涂抹层”。最近 IADR关于涂抹层的研讨会指出，人们对 这一层对牙本质渗透性和牙本质反应性的影响 涂抹层本身和对试剂的潜在声音牙本质 旨在与牙本质中的钙和胶原成分发生反应。 对其颗粒大小分布或孔隙率知之甚少。 使用低速和高速毛刺、砂纸圆盘和高速毛刺产生的涂抹层 钻石轮子。目前还没有系统的努力来量化 涂抹层厚度或由以上创建的涂抹层的效果 牙本质渗透性的测定方法。无数的制造商已经开发出 “牙本质粘结剂”促进修复树脂的“粘结” 牙本质上覆盖着一层涂抹层。这样的代理人应该会大大减少 牙本质的渗透性，但还没有做过这样的定量研究。 这项拟议的研究将评估涂抹层对牙本质的影响 渗透率测量为水力传导性(Lp)。LP测定 还将确定各种物理和治疗方法的有效性 去除污渍层的化学方法。剩余部分的反应性 牙本质表面将通过测量摄取45Ca和 3 H-氨基试剂。涂抹层厚度将从 牙本质表面涂片碎屑中钙、磷和羟脯氨酸的含量。 犬牙本质通透性降低的活体测量 空洞准备将继续努力，以发现潜在的 机制(S)。由于这一现象可能是由于轴突反射，传入 通过外科手术去神经去下颌神经可以去除四肢。 和/或颈上交感神经空洞前3-4周 准备工作。反射的传出侧将通过放置 P物质拮抗剂在腔内或通过静脉给药 抗炎药，如地塞米松、阿司匹林等 在降低牙本质渗透性方面，将尝试如外用 先使用纤维蛋白原溶液，然后局部使用 凝血酶。

Almost all dental restorations are placed on dentin which is covered by a layer of microcrystalline debris--the so-called "smear layer". A recent IADR symposium on the smear layer pointed out how little is known about the influence that this layer has on dentin permeability and the reactivity of both the smear layer itself and the underlying sound dentin to reagents designed to react with the calcium and collagen components of dentin. Little is known regarding the particle size distribution or porosity of smear layers produced with low vs high speed burs, sand paper discs vs diamond wheels. No systematic efforts have been directed to quantitate smear layer thickness or the effects of smear layers created by the above methods on dentin permeability. Numerous manufacturers have developed "dentin bonding agents" to facilitate the "bonding" of restorative resins with dentin covered by a smear layer. Such agents should greatly reduce dentin permeability but no such quantitative studies have been done. The proposed research will evaluate the effects of smear layers on dentin permeability measured as hydraulic conductance (Lp). Lp determinations will also be done to determine the effectiveness of various physical and chemical methods of removing smear layers. The reactivity of the remaining dentin surfaces will be evaluated by measuring the uptake of 45Ca and 3H-amino group reagents. Smear layer thickness will be calculated from the Ca, P and hydroxyproline contents of smear debris sonicated off of dentin. In vivo measurements of the decrease in dog dentin permeability following cavity preparations will continue in an effort to discover the underlying mechanism(s). As the phenomenon may be due to an axon reflex, the afferent limb will be eliminated by surgically denervating the mandibular nerve and/or superior cervical sympathetic nerve 3-4 weeks prior to cavity preparation. The efferent side of the reflex will be blocked by placing substance P antagonists in the cavity or by iv administration of anti-inflammatory agents like dexamethasone, aspirin, etc. New approaches at reducing dentin permeability, acutely, will be tried such as topical application of fibrinogen solution followed by topical application of thrombin.