School of Dentistry, University of Manchester, UK.
Dent Mater. 2012 Jun;28(6):609-14. doi: 10.1016/j.dental.2012.01.007. Epub 2012 Feb 18.
The aim of this study was to investigate the effect of variations in filler particle size and shape on the polymerization shrinkage-stress kinetics of resin-composites.
A model series of 12 VLC resin-composites were studied. The particulate dispersed phase volume fraction was 56.7%: these filler particles were systematically graded in size, and further were either spherical or irregular. A Bioman instrument (cantilever beam method) was employed to determine the shrinkage-stress kinetics following 40s irradiation (600 mW/cm(2)) at 23°C (n=3). All data were captured for 60 min and the final shrinkage-stress calculated.
Shrinkage-stress varied between 3.86 MPa (SD 0.14) for S3 (spherical filler particles of 500 nm) and 8.44 MPa (SD 0.41) for I1 (irregular filler particles of 450 nm). The shrinkage-stress values were generally lower for those composites with spherical filler particles than those with irregular filler particles. The differences in shrinkage-stress with filler particle size and shape were statistically significant (p<0.001).
Composites with spherical filler particles exhibit lower shrinkage-stress values compared to those with irregular filler particles. Shrinkage-stress and shrinkage-stress rate vary in a complex manner with variations in the size of the dispersed phase particles: a hypothesized explanation for the effect of filler particle size and shape is presented.
本研究旨在探讨填料粒径和形状的变化对树脂复合材料聚合收缩应力动力学的影响。
研究了一系列 12 种 VLC 树脂复合材料。分散相体积分数为 56.7%：这些填料颗粒按大小系统分级，进一步分为球形或不规则形状。采用 Bioman 仪器（悬臂梁法）在 23°C（n=3）下 600mW/cm²光照 40s 后测定收缩应力动力学。所有数据均在 60min 内采集，计算最终收缩应力。
收缩应力在 S3（500nm 球形填料颗粒）的 3.86MPa（SD 0.14）和 I1（450nm 不规则填料颗粒）的 8.44MPa（SD 0.41）之间变化。具有球形填料颗粒的复合材料的收缩应力值通常低于具有不规则填料颗粒的复合材料。填料颗粒大小和形状对收缩应力的影响具有统计学意义（p<0.001）。
与具有不规则填料颗粒的复合材料相比，具有球形填料颗粒的复合材料表现出较低的收缩应力值。收缩应力和收缩应力速率随分散相颗粒尺寸的变化以复杂的方式变化：提出了填料颗粒尺寸和形状影响的假设解释。
