Hahn R, Löst C
Poliklinik für Zahnerhaltung, Universität Tübingen.
Schweiz Monatsschr Zahnmed. 1993;103(7):844-50.
In this study, the influence of a new ultrasonic shaping procedure on the surface quality, microstructure, bending strength and fatigue behaviour of a feldspathic porcelain was investigated. A total of 120 standardized (ISO 6872) autoglazed, ground, lapped and ultrasonically machined porcelain test bars were analyzed. Another 24 equiformat experimental alumina ceramics, which were ultrasonically machined, as well as 24 nontreated fload glass specimen served as controls. It could be shown that the porcelain removal process with diamond grinding wheels yielded a rough surface microrelief and lead to structural subsurface damage, decreasing bending strength and fatigue behaviour. In contrast, ultrasonic shaping resulted in a smoother surface and prevented damage to the subsurface layer of the machined brittle porcelain, although, the smoothest surfaces were achieved by lapping. Both bending strength and fatigue behaviour of the conventional dental porcelain were increased by ultrasonic machining. However, the fracture toughness of the experimental alumina was substantially higher and was not subjected to a decrease in fatigue.
在本研究中，研究了一种新型超声加工工艺对长石质瓷表面质量、微观结构、弯曲强度和疲劳行为的影响。共分析了120根符合标准（ISO 6872）的自釉、磨削、研磨和超声加工的瓷测试棒。另外24根经过超声加工的等规格实验性氧化铝陶瓷以及24个未处理的浮法玻璃试样作为对照。结果表明，使用金刚石砂轮进行瓷去除加工会产生粗糙的表面微观起伏，并导致结构次表面损伤，降低弯曲强度和疲劳性能。相比之下，超声加工可使表面更光滑，并防止加工后的脆性瓷次表面层受损，不过，通过研磨可获得最光滑的表面。超声加工提高了传统牙科瓷的弯曲强度和疲劳性能。然而，实验性氧化铝的断裂韧性明显更高，且疲劳性能未降低。
