Department of Building and Civil Engineering, Faculty for the Built Environment, University of Malta, Malta.
J Endod. 2010 Mar;36(3):502-8. doi: 10.1016/j.joen.2009.10.018. Epub 2010 Jan 25.
Mineral trioxide aggregate (MTA) is composed of calcium silicate cement and bismuth oxide added for radiopacity. The bismuth oxide in MTA has been reported to have a deleterious effect on the physical and chemical properties of the hydrated material. This study aimed to investigate the hydration mechanism of calcium silicate cement loaded with different radiopacifiers for use as a root-end filling material.
Calcium silicate cement loaded with barium sulfate, gold, or silver/tin alloy was hydrated, and paste microstructure was assessed after 30 days. In addition, atomic ratio plots of Al/Ca versus Si/Ca and S/Ca and Al/Ca were drawn, and X-ray energy dispersive analysis of the hydration products was performed to assess for inclusion of heavy metals. The leachate produced from the cements after storage of the cements in water for 28 days and the leaching of the radiopacifiers in an alkaline solution was assessed by using inductively coupled plasma.
The hydrated calcium silicate cement was composed of calcium silicate hydrate, calcium hydroxide, ettringite, and monosulfate. Unhydrated cement particles were few. No heavy metals were detected in the calcium silicate hydrate except for the bismuth in MTA. Calcium was leached out early in large quantities that reduced with time. The barium and bismuth were leached in increasing amounts. Copper was the most soluble in alkaline solution followed by bismuth and barium in smaller amounts.
The bismuth oxide can be replaced by other radiopacifiers that do not affect the hydration mechanism of the resultant material.
矿化三氧化物聚合体（MTA）由硅酸钙水泥和添加了放射增感剂的氧化铋组成。据报道，MTA 中的氧化铋会对水合材料的物理和化学性质产生有害影响。本研究旨在探讨作为根尖封闭材料使用的不同放射增感剂负载的硅酸钙水泥的水化机制。
将硫酸钡、金或银/锡合金负载的硅酸钙水泥水化，并在 30 天后评估糊剂的微观结构。此外，绘制 Al/Ca 与 Si/Ca 和 S/Ca 的原子比图，并对水化产物进行 X 射线能量色散分析，以评估重金属的存在。将水泥在水中储存 28 天后产生的浸出液和碱性溶液中放射增感剂的浸出液用电感耦合等离子体进行评估。
水化硅酸钙水泥由硅酸钙水合物、氢氧化钙、钙矾石和单硫酸盐组成。未水化的水泥颗粒很少。除了 MTA 中的铋之外，硅酸钙水合物中未检测到重金属。大量的钙早期被浸出，随着时间的推移逐渐减少。钡和铋的浸出量逐渐增加。铜在碱性溶液中最易溶解，其次是铋和钡。
可以用不会影响材料水化机制的其他放射增感剂来替代氧化铋。
