EVALUATION OF MERCURY RELEASE FROM DENTAL AMALGAMS

本延续申请的总体目标是开发牙科 汞合金释放的汞含量明显低于 目前的商业汞合金。我们的研究表明， 开发含有大颗粒的γ 1（Ag-Hg）基质的汞合金 易氧化的金属，如锡和铟的量， 从而使汞合金的汞排放量显著减少。这 还原将由抑制表面的形成引起 氧化物，以及汞的蒸气压降低 汞合金的释放阶段。 三个具体目标是：#1）开发一系列二元和 含有不同浓度汞的三元合金 容易氧化的金属，即铟、锡和锌，它们可以被使用 作为液相与普通牙科汞合金研磨 #2）充分表征汞合金的特性 由目标1中开发的最有前途的合金生产;和#3） 为了解释的性质和汞的释放特性， 最有前途的汞合金，通过检查其微观结构，基质相， 组成、蒸汽压和热稳定性。 为了实现这一目标，汞和铟的二元液态合金， 将混合汞、铟和锡或锌的三元液态合金 用四种不同类型的普通牙科汞合金粉末， 生产汞合金。对大约24种汞合金进行初步筛选 将通过测定凝结过程中的汞蒸发来进行， 通过比较一小时抗压强度、蠕变和尺寸 变更为ANSI/ADA规范#1汞合金的最小值。 通过筛选过程的制剂将被完全 在具体目标#2中，通过定量汞蒸发来表征 磨损后，1天和7天抗压强度，弯曲 强度，工作时间和处理，耐腐蚀性;溶解 静态和动态腐蚀过程中的元素，和细胞毒性。 最后，将对显微组织和相分析进行全面评价。 通过扫描电子显微探针、有限表面分析进行 将通过俄歇光谱学和热重分析法收集数据， 差示扫描量热法将用于测量蒸汽 汞合金的压力和热稳定性。

The overall goal of this continuation application is to develop dental amalgams which release significantly lower levels of mercury than current commercial amalgams. Our studies have suggested that the development of amalgams with gamma 1 (Ag-Hg) matrices containing large amounts of readily oxidized metals, such as tin and indium, should result in amalgams with significantly reduced mercury release. This reduction would result from the formation of an inhibiting surface oxide, as well as to a reduction in the vapor pressure of the mercury releasing phases of amalgam. The three specific aims are: #1) To develop a series of binary and ternary alloys containing mercury with varying concentrations of readily oxidized metals, i.e. indium, tin and zinc, which can be used as-the liquid phase for trituration with common dental amalgam alloy powders; #2) To fully characterize the properties of the amalgams produced from the most promising alloys developed in aim one; and #3) To explain the properties and mercury release characteristics for the most promising amalgams by examining their microstructure, matrix phase composition, and vapor pressure and thermal stability. To accomplish the aims, binary liquid alloys of mercury and indium and ternary liquid alloys of mercury, indium and tin or zinc, will be mixed with four different types of common dental amalgam alloy powders to produce amalgams. An initial screening of approximately 24 amalgams will be conducted by determining mercury vaporization during setting, and by comparing one-hour compressive strength, creep and dimensional change to the ANSI/ADA Specification #1 minimum values for amalgams. Formulations which pass the screening process will be fully characterized in specific aim #2 by quantitating mercury vaporization after abrasion, 1-day and 7-day compressive strength, flexural strength, working time and handling, corrosion resistance; dissolution of elements during static and dynamic corrosion, and cytotoxicity. Finally, a full evaluation of microstructure and phase analysis will be performed by scanning electron microprobe, limited surface analysis data will be collected by Auger spectroscopy, and thermalgravimetry and differential scanning calorimetry will be used to measure vapor pressure and thermal stability of the amalgams.