Storm Buffy, Eichmiller Frederick C, Tordik Patricia A, Goodell Gary G
Naval Postgraduate Dental School, Bethesda, Maryland, USA.
J Endod. 2008 Jan;34(1):80-2. doi: 10.1016/j.joen.2007.10.006.
One possible reason for the sealing ability of mineral trioxide aggregate (MTA) is its slight expansion upon setting. Both gray mineral trioxide aggregate (GMTA) and white mineral trioxide aggregate (WMTA) are composed of approximately 75% Portland cement (PC). WMTA differs from GMTA in its lower content of tetracalcium aluminoferrite. This difference in composition may affect setting expansion. The purpose of this study was to compare the hydroscopic linear setting expansions of GMTA, WMTA, and PC with a new device. Materials were mixed with water, placed into a cylindrical mold, and covered with sterile water or Hank's balanced salt solution (HBSS). Expansion changes were measured by using a linear variable displacement transformer dilatometer. One-way analysis of variance and post hoc tests (alpha = 0.05) showed the mean expansion at 24 hours was 1.02% for GMTA, 0.29% for PC, and 0.08% for WMTA in water immersion and 0.68% for GMTA and 0.11% for WMTA in HBSS immersion. GMTA expanded significantly more than WMTA in either water or HBSS immersion.
三氧化矿物凝聚体（MTA）具有封闭能力的一个可能原因是其在凝固时会轻微膨胀。灰色三氧化矿物凝聚体（GMTA）和白色三氧化矿物凝聚体（WMTA）均由约75%的波特兰水泥（PC）组成。WMTA与GMTA的区别在于其铁铝酸四钙含量较低。这种成分差异可能会影响凝固膨胀。本研究的目的是使用一种新装置比较GMTA、WMTA和PC的吸湿线性凝固膨胀情况。将材料与水混合，放入圆柱形模具中，并用无菌水或汉克斯平衡盐溶液（HBSS）覆盖。使用线性可变位移传感器膨胀仪测量膨胀变化。单因素方差分析和事后检验（α = 0.05）表明，在水浸条件下，GMTA在24小时时的平均膨胀率为1.02%，PC为0.29%，WMTA为0.08%；在HBSS浸条件下，GMTA为0.68%，WMTA为0.11%。在水浸或HBSS浸条件下，GMTA的膨胀均显著大于WMTA。
