Linde L A
Swed Dent J. 1983;7(5):205-14.
To study how repeated temperature variations, "thermal stress", will influence the cement retention between composite materials--formed as cores--and gold crowns, extracted permanent teeth were prepared to core form. Stylized gold crowns were waxed up on the dentine preparations and cast, four for each of three chosen preparations, which in their turn were used to form cores in gold and three different composite materials. The attempt was to achieve four as similar test-pieces as possible for each core shape. Two new cements and four zinc phosphate cements were used as retaining medium for 48 test series. Four similar test-pieces have each time been subject to thermo-cycling during 12 hours in a specially designed apparatus. The temperature intervals were 0 degree C, 25 degrees C and 50 degrees C. Each series has then been loaded into a tensiometer and stressed until the cement retention was overcome. The test results showed that microfill composite cores were associated with least retention values. For the other materials: gold and macrofill composites (two paste system and single paste system), no differences were to be seen. The retentive ability for one (a zinc phosphate cement, normal- and fast-setting) of five different cements differed remarkably: about double the load was required to loosen the core from its crown than when any of the other cements was used.
为研究反复的温度变化，即“热应力”，如何影响作为核体成型的复合材料与金冠之间的粘固剂保留情况，将拔除的恒牙制备成核体形状。在牙本质制备物上用蜡制作风格化的金冠并铸造，三种选定的制备物每种制作四个，然后分别用金和三种不同的复合材料制作核体。目标是为每种核体形状获得四个尽可能相似的试件。两种新型粘固剂和四种磷酸锌粘固剂被用作48个测试系列的固定介质。每次四个相似的试件在专门设计的仪器中进行12小时的热循环。温度区间为0摄氏度、25摄氏度和50摄氏度。然后将每个系列加载到张力计中并施加应力，直到粘固剂保留被克服。测试结果表明，微填料复合核体的保留值最低。对于其他材料：金和大填料复合材料（双糊剂系统和单糊剂系统），未观察到差异。五种不同粘固剂中的一种（一种磷酸锌粘固剂，常规固化和快速固化）的固位能力有显著差异：将核体从牙冠上松开所需的负荷约为使用其他任何一种粘固剂时的两倍。
