PERMEABILITY CHARACTERISTICS OF DENTIN

几乎所有的牙科修复体都放置在牙本质上， 一层微晶碎片--所谓的“玷污层”。 最近的一 关于玷污层的IADR研讨会指出，人们对 该层对牙本质渗透性和 玷污层本身和下面的完好牙本质都被试剂 其被设计成与牙本质的钙和胶原成分反应。 关于纳米颗粒的粒度分布或孔隙率知之甚少。 低速与高速布尔斯钻、砂纸盘与 钻石轮 没有系统的努力来量化 涂抹层厚度或由上述方法产生的涂抹层效果 牙本质渗透性的方法。 许多制造商开发了 促进修复树脂“粘合”的“牙本质粘合剂” 牙本质被玷污层覆盖 这些药物应大大减少 牙质渗透性，但没有进行这样的定量研究。 这项研究将评估玷污层对牙本质的影响 渗透率测量为水力传导率（Lp）。 Lp测定 还将确定各种物理和 去除玷污层的化学方法。 剩余的反应性 牙本质表面将通过测量45 Ca的摄取来评估， 3 H-氨基试剂。 将根据以下公式计算烧结层厚度： 超声处理牙本质脱落物中Ca、P和羟脯氨酸含量的变化。 狗牙本质渗透性降低的体内测量， 牙洞准备工作将继续努力，以发现潜在的 机制。 由于这种现象可能是由于轴突反射，传入神经可能是神经元。 通过手术切除下颌神经， 和/或上级颈交感神经3-4周前的腔 准备. 反射的传出侧将被阻断， P物质拮抗剂在腔中或通过静脉内施用 抗炎药，如地塞米松，阿司匹林等。 在减少牙本质渗透性，急性，将尝试，如局部 应用纤维蛋白原溶液，然后局部应用 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.