Papazoglou E, Brantley W A, Johnston W M
Section of Restorative Dentistry, Prosthodontics, and Endodontics, College of Dentistry, The Ohio State University, Columbus, Ohio, USA.
J Prosthet Dent. 2001 Feb;85(2):133-40. doi: 10.1067/mpr.2001.113707.
Crown fit is a prerequisite for long-term clinical success; however, crown distortion may occur during porcelain firing. The dimensional stability of some high-palladium alloys at high temperatures has been questioned.
The purpose of this study was to use a new method to measure the distortion of copings for metal-ceramic single units of selected high-palladium alloys with compositions representative of commercial alloys.
Four high-palladium alloys containing copper and 3 containing no copper were tested. A palladium-silver alloy was included for comparison, and a gold-palladium alloy served as the control. By using reference points scribed on the margin, the mesiodistal and buccolingual margin diameters of identical copings were measured with a traveling microscope at 4 stages: as-cast, oxidized, after 2 simulated opaque porcelain firings, and after 2 simulated dentin porcelain firings. The margin distortions for the various specimen groups representing combinations of alloys, stages, and measurement diameters were compared with the use of 1-way analysis of variance and a multiple range test.
Most of the high-palladium alloys had high-temperature distortions that were not significantly different from those of the control alloy. The distortions occurred principally during the oxidation cycle. The effect of mesiodistal groove reinforcement on preventing distortion was not the same for all alloys.
The results suggest that small observed distortions of these alloys will not produce clinical problems. Several laboratory techniques are available to counteract the distortions.
牙冠贴合是长期临床成功的前提条件；然而，在烤瓷烧制过程中可能会发生牙冠变形。一些高钯合金在高温下的尺寸稳定性受到质疑。
本研究的目的是使用一种新方法来测量选定的具有商业合金代表性成分的高钯合金金属烤瓷单冠修复体基底冠的变形情况。
测试了四种含铜的高钯合金和三种不含铜的高钯合金。纳入一种钯银合金进行比较，并采用一种金钯合金作为对照。通过使用刻划在边缘的参考点，在四个阶段用移动显微镜测量相同基底冠的近远中及颊舌向边缘直径：铸态、氧化后、两次模拟不透明瓷烧制后以及两次模拟牙本质瓷烧制后。使用单向方差分析和多重极差检验比较代表合金、阶段和测量直径组合的各个样本组的边缘变形情况。
大多数高钯合金的高温变形与对照合金的变形无显著差异。变形主要发生在氧化阶段。近远中沟增强对防止变形的效果并非对所有合金都相同。
结果表明，观察到的这些合金的微小变形不会产生临床问题。有几种实验室技术可用于抵消这些变形。
