Mueller H J
Council on Dental Materials, Instruments, and Equipment, American Dental Association, Chicago, Illinois, 60611.
Scanning Microsc. 1990 Jun;4(2):297-307.
The plane strain fracture toughness (K1c) at 23 degrees C and the fractography of zinc phosphate and zinc polycarboxylate cements, buffered glass ionomer liner, amalgam alloy admixed glass ionomer build-up material, and glass ionomer, microfilled and conventionally filled bis-GMA resin composite filling materials were analyzed by elastic-plastic short-rod and scanning electron microscopy methodologies. Results indicated that significant differences occurred in their K1c's from the lowest to the highest in the following groups of materials, (i) buffered glass ionomer, (ii) zinc phosphate, glass ionomer, zinc polycarboxylate, and alloy mixed glass ionomer, (iii) microfilled resin, and (iv) conventionally filled resin. All materials except the microfilled resin, which fractured via crack jumping, fractured via smooth crack advance. Filler debonding without any crack inhibiting process was related to materials with low K1c values. The incorporation of either buffering compounds or alloy particles into glass ionomer had no beneficial effect upon fracture toughness. This was in contrast to microfilled and conventionally filled resins where either crack blunting or crack pinning processes, respectively, were likely involved with their increased K1c's. For microfilled resin, distinct radial zones positioned around the chevron apex and characterized by plastically deformed deposited material were related to distinct crack jumps that occurred in the load versus displacement behavior. Finally, for the two remaining materials of zinc phosphate and polycarboxylate, particle cleavage and matrix debonding for the former and shear yielding for the latter occurred.
采用弹塑性短棒和扫描电子显微镜方法，分析了23摄氏度下磷酸锌和聚羧酸锌水门汀、缓冲型玻璃离子衬层材料、汞合金混合玻璃离子增强材料以及玻璃离子、微填料型和传统填料型双酚A缩水甘油醚（bis - GMA）树脂复合充填材料的平面应变断裂韧性（K1c）和断口形貌。结果表明，以下几组材料的K1c值从最低到最高存在显著差异：（i）缓冲型玻璃离子；（ii）磷酸锌、玻璃离子、聚羧酸锌和合金混合玻璃离子；（iii）微填料型树脂；（iv）传统填料型树脂。除微填料型树脂通过裂纹跳跃断裂外，所有材料均通过平滑裂纹扩展断裂。在没有任何裂纹抑制过程的情况下，填料脱粘与低K1c值的材料有关。在玻璃离子中加入缓冲化合物或合金颗粒对断裂韧性没有有益影响。这与微填料型和传统填料型树脂形成对比，在微填料型和传统填料型树脂中，分别可能是裂纹钝化或裂纹钉扎过程导致其K1c值增加。对于微填料型树脂，位于人字形尖端周围、以塑性变形沉积材料为特征的明显径向区域与载荷-位移行为中发生的明显裂纹跳跃有关。最后，对于剩余的磷酸锌和聚羧酸锌这两种材料，前者发生颗粒解理和基体脱粘，后者发生剪切屈服。
