PERMEABILITY CHARACTERISTICS OF DENTIN

牙本质的渗透性是临床研究的核心 诸如牙本质敏感性和牙髓反应的问题 龋齿、微渗漏、牙科手术和材料。 我们的大多数 以前的工作仅限于研究咬合牙本质， 年轻未萌出的第三磨牙 我们建议使用相同的 方法学研究的渗透性萌出的牙齿作为一个 年龄的函数。 咬合面、颊面、近端和牙根牙本质 渗透率将进行比较，并与SEM研究相关， 这些标本。 冠、根牙本质的牙髓面 将在粘合之前接受各种处理， Gluma或Superbond处理表面的粘合强度。 根管治疗的牙齿可能会加强内部牙本质 前将芯片 在这些研究中，我们将尝试开发简单的临床 估计体内牙本质渗透性的适用方法， 染料和测量牙本质的电阻。 玷污层占据了材料之间的临界界面 牙齿结构。 我们将继续研究 以及通过表征渗透性来确定涂抹层的功能， SEM外观实践。 2级置换的微渗漏 将使用已应用于Class 1的方法进行评估 插入后，作为完成手术的函数的扩张 时间和热循环。 我们最近发现，储存粘结试样， 模拟的生理牙髓压力导致粘结强度 下降50%。 这些研究将扩大到包括各种 压力、时间间隔和液体成分 如在体内。 我们将收集用于SEM和粒度的玷污层 分析并检查体内涂片层的寿命。 我们以前的工作表明，内源性纤维蛋白原可以泄漏， 从受刺激的牙髓血管进入牙本质小管， 降低牙本质渗透性。 这一假设将由以下人员进行检验： 检测放射性纤维蛋白原在体外的分布， 在狗体内使用光显微镜放射自显影作为 浅腔与深腔制备后时间的函数 犬预给药前后的腔体准备 地塞米松来阻断炎症反应。

The permeability properties od dentin are central to clinical problems such as dentin sensitivity and the pulpal reactions to caries, microleakage, dental procedures and materials. Most of our previous work has been confined to studies of occlusal dentin in young, unerupted third molars. We propose to use the same methodology to study the permeability of erupted teeth as a function of age. Occlusal, buccal, proximal and root dentin permeabilities will be compared and correlated with SEM studies of these specimens. The pulpal surfaces of coronal and root dentin will receive various treatments prior to bonding to try to optimize the bond strengths of Gluma or Superbond treated surfaces. Endodontically treated teeth may be strengthened by internal dentin bonding. During these studies, we will attempt to develop simple clinically applicable methods of estimating dentin permeability in vivo using dyes and by measuring the electrical resistance of dentin. The smear layer occupies the critical interface between materials and tooth structure. We will extend our studies of the structure and function of the smear layer by characterizing the permeability, SEM appearance practice. The microleakage of class 2 restorations will be evaluated using methods already applied to Class 1 restorations as a function of finishing procedures, post-insertion time and thermal cycling. We have recently discovered that storage of bonded specimens under a simulated physiological pulpal pressure causes the bond strength to fall 50%. These studies will be extended to include various pressures, time intervals and fluid composition in vitro and well as in vivo. We will collect smear layers for SEM and particle size analysis as well as examine the longevity of in vivo smear layers. Our previous work indicates that endogenous fibrinogen can leak from irritated pulpal blood vessels into dentinal tubules thereby decreasing dentin permeability. This hypothesis will be tested by examining the distribution of radioactive fibrinogen in vitro and in vivo in dogs using light microscopic radioautography as a function of time after cavity preparation in superficial vs deep cavity preparations before and after premedicating the dogs with dexamethasone to block the inflammatory response.