Eichmiller Frederick C, Hoffman Kathleen M, Guiseppetti Anthony A, Wray Michael M, Avers Rangall J
American Dental Association Health Foundation, Paffenbarger Research Center, National Institute of Standards and Technology, Gaithersburg, MD 20899-0001.
Naval Dental School Bethesda, MD 20899-5602.
J Res Natl Inst Stand Technol. 1998 Sep-Oct;103(5):511-516. doi: 10.6028/jres.103.031. Epub 1998 Oct 1.
Silver-rich metal powders cold-welded by consolidation have been investigated as possible direct dental filling material. The surface of the silver powder must undergo an acid treatment to remove existing contaminants and prevent formation of new surface contaminants during consolidation. This study was designed to investigate the effect of the acid treatment on the strength of the consolidated alloy, its reactivity with the surrounding tooth structure, and its reactions with certain cavity liners. This study investigated the effects of pH and concentration of fluoboric acid on the flexural strength of silver powder consolidated into rectangular beams in a partial 4 × 4 design. The study also assessed, by visible and scanning electron microscopy, what effect the acid-treated powders had on dentin that had been pre-coated with different cavity liners. Mean flexural strengths for beams consolidated using dental hand instruments were in the range (77.0 ± 9.28) MPa to (166.1 ± 17.6) MPa, where the quoted uncertainties are standard uncertainties (i.e., one standard deviation estimates). ANOVA indicated that fluoboric acid pH was highly significant ( < 0.0001) with lower pH values resulting in higher flexural strength. Concentration alone was not a significant factor for flexural strengths, but there was a significant interaction between concentration and pH ( < 0.0001). Microscopy revealed that the acid-treated silver powder demineralized approximately 2 μm of dentin when used with no liner. The use of copal or polyamide varnishes eliminated most of this demineralization, but the use of a dentin adhesive liner resulted in some dislodgment and breakdown of the adhesive film by the acid. The results of this study indicate that this silver powder when treated with dilute fluoboric acid at a pH of approximately 1.0 can result in a filling material with strength equivalent to currently used conventional amalgam. The demineralization of tooth structure appears to be minimal and can be eliminated with the use of cavity liners.
通过固结冷焊的富银金属粉末已被作为可能的直接牙科填充材料进行研究。银粉表面必须进行酸处理，以去除现有的污染物，并防止在固结过程中形成新的表面污染物。本研究旨在调查酸处理对固结合金强度、其与周围牙齿结构的反应性以及与某些窝洞衬层的反应的影响。本研究采用部分4×4设计，研究了氟硼酸的pH值和浓度对固结成长方形梁的银粉抗弯强度的影响。该研究还通过可见光和扫描电子显微镜评估了酸处理后的粉末对预先涂有不同窝洞衬层的牙本质有何影响。使用牙科手持器械固结的梁的平均抗弯强度范围为(77.0±9.28)MPa至(166.1±17.6)MPa，其中引用的不确定度为标准不确定度（即一个标准偏差估计值）。方差分析表明，氟硼酸pH值具有高度显著性（<0.0001），较低的pH值导致较高的抗弯强度。单独的浓度不是抗弯强度的显著因素，但浓度和pH值之间存在显著的相互作用（<0.0001）。显微镜检查显示，当不使用衬层时，酸处理后的银粉使约2μm的牙本质脱矿。使用珂罗酊或聚酰胺清漆可消除大部分这种脱矿现象，但使用牙本质粘结衬层会导致酸使粘结膜出现一些移位和破裂。本研究结果表明，这种银粉在pH值约为1.0的稀氟硼酸处理下，可得到一种强度与目前使用的传统汞合金相当的填充材料。牙齿结构的脱矿现象似乎最小，并且可以通过使用窝洞衬层来消除。
