Hutton J E, Marshall G W
Department of Restorative Dentistry, School of Dentistry, University of California, San Francisco.
J Prosthet Dent. 1993 Aug;70(2):121-5. doi: 10.1016/0022-3913(93)90005-9.
Less expensive silver and palladium (AgPd) dental casting alloys are popular, but require phosphate bonded investments. The physical properties of such materials have not been thoroughly investigated. This study determined whether three different phosphate bonded investments could provide adequate expansion to compensate for the casting shrinkage of AgPd. The investments were mixed with distilled water or their unique special liquids provided by the manufacturers and allowed setting times of 1 hour or 24 hours. Setting expansions were measured with a vertical dilatometer. When mixed with special liquid, material I had a mean setting (1 hour) expansion of 0.19% +/- 0.01%; material II, 0.14% +/- 0.03%; and material III, 1.17% +/- 0.08%. Twenty-four hours of setting did not significantly increase the setting expansion (p > 0.05). Mixing the three investments with distilled water drastically reduced setting expansions. A three-way analysis of variance was computed to evaluate the data and investigate significant interactive and main effects. The two-way interaction (material x liquid) was significant. The results were consistent with the concept of a higher silica-containing special liquid for material III compared with the other materials.
价格较为低廉的银钯（AgPd）牙科铸造合金很受欢迎，但需要使用磷酸盐粘结包埋材料。此类材料的物理性能尚未得到充分研究。本研究确定了三种不同的磷酸盐粘结包埋材料能否提供足够的膨胀以补偿AgPd的铸造收缩。将这些包埋材料与蒸馏水或制造商提供的特制液体混合，并设定凝固时间为1小时或24小时。使用垂直膨胀仪测量凝固膨胀。与特制液体混合时，材料I的平均凝固（1小时）膨胀率为0.19%±0.01%；材料II为0.14%±0.03%；材料III为1.17%±0.08%。24小时的凝固并未显著增加凝固膨胀（p>0.05）。将这三种包埋材料与蒸馏水混合会大幅降低凝固膨胀。计算了三因素方差分析以评估数据并研究显著的交互作用和主效应。双向交互作用（材料×液体）显著。结果与以下概念一致：与其他材料相比，材料III使用的是含二氧化硅量更高的特制液体。
