Albakry Mohammad, Guazzato Massimiliano, Swain Michael Vincent
Biomaterials Science Research Unit, Faculty of Dentistry, University of Sydney, Suite G11, National Innovation Centre, Australian Technology Park, 1430, Eveleigh, NSW, Australia.
J Dent. 2004 Feb;32(2):91-9. doi: 10.1016/j.jdent.2003.08.006.
During laboratory fabrication procedures and/or clinical adjustments, pressable materials: IPS Empress and Empress 2, may be ground, polished or sandblasted. These treatments may affect their strength by introducing microscopic flaws and defects. This study investigates the effect of these procedures on the mean flexural strength of these materials.
One hundred and forty disc specimens (14mmx1 mm) of IPS Empress and Empress 2 were prepared, and divided into seven groups of 20 specimens for each material. Groups were untreated, polished, polished and glazed, ground, ground and glazed, sandblasted, sandblasted and glazed. Surface roughness, mean biaxial flexural strength and Weibull modulus were appraised, and a scanning electron microscope was used to describe surface features. Statistical significance among groups of population was analysed using one-way Anova and Tukey's multiple comparison tests.
Untreated and sandblasted groups showed significantly the highest roughness values, and polished the lowest for each material (p<0.05). Ground groups showed significantly lower roughness values than the sandblasted groups, and significantly higher roughness than the polished groups for each material (p<0.05). Polished groups for each material demonstrated significantly the highest mean flexural strength values (p<0.05). No significant difference in the mean strength values was found between untreated, sandblasted and ground groups for each material (p>0.05). Heat treatment had no effect on roughness or strength values of all treated groups of both materials. The Weibull modulus values for both materials varied with different treatments. They showed higher values for polished and untreated groups, and lower values for ground and sandblasted groups.
Surface roughness may not be the only feature that determines strength. Other issues such as porosity, microstructural residual stresses, surface and bulk defects may also be pertinent.
在实验室制作过程和/或临床调整过程中，可压铸材料IPS Empress和Empress 2可能会被磨削、抛光或喷砂处理。这些处理可能会因引入微观缺陷而影响其强度。本研究调查这些处理对这些材料平均抗弯强度的影响。
制备了140个IPS Empress和Empress 2的圆盘试样（14mm×1mm），每种材料分为7组，每组20个试样。分组为未处理、抛光、抛光并上釉、磨削、磨削并上釉、喷砂、喷砂并上釉。评估了表面粗糙度、平均双轴抗弯强度和威布尔模量，并使用扫描电子显微镜描述表面特征。使用单因素方差分析和Tukey多重比较检验分析各组总体之间的统计学显著性。
未处理组和喷砂组的粗糙度值显著最高，每种材料的抛光组粗糙度值最低（p<0.05）。每种材料的磨削组粗糙度值显著低于喷砂组，显著高于抛光组（p<0.05）。每种材料的抛光组平均抗弯强度值显著最高（p<0.05）。每种材料的未处理组、喷砂组和磨削组之间的平均强度值无显著差异（p>0.05）。热处理对两种材料所有处理组的粗糙度或强度值均无影响。两种材料的威布尔模量值随不同处理而变化。抛光组和未处理组的值较高，磨削组和喷砂组的值较低。
表面粗糙度可能不是决定强度的唯一因素。其他问题，如孔隙率、微观结构残余应力、表面和整体缺陷也可能相关。
