Department of Building and Civil Engineering, Faculty for the Built Environment, University of Malta, Msida MSD 2080, Malta.
Dent Mater. 2011 Aug;27(8):845-54. doi: 10.1016/j.dental.2011.04.011. Epub 2011 May 14.
Zirconium oxide can be added to dental materials rendering them sufficiently radiopaque. It can thus be used to replace the bismuth oxide in mineral trioxide aggregate (MTA). Replacement of Portland cement with 30% zirconium oxide mixed at a water/cement ratio of 0.3 resulted in a material with adequate physical properties. This study aimed at investigating the microstructure, pH and leaching in physiological solution of Portland cement replaced zirconium oxide at either water-powder or water-cement ratios of 0.3 for use as a root-end filling material. The hydration characteristics of the materials which exhibited optimal behavior were evaluated.
Portland cement replaced by zirconium oxide in varying amounts ranging from 0 to 50% in increments of 10 was prepared and divided into two sets. One set was prepared at a constant water/cement ratio while the other set at a constant water/powder ratio of 0.3. Portland cement and MTA were used as controls. The materials were analyzed under the scanning electron microscope (SEM) and the hydration products were determined. X-ray energy dispersive analysis (EDX) was used to analyze the elemental composition of the hydration products. The pH and the amount of leachate in Hank's balanced salt solution (HBSS) were evaluated. A material that had optimal properties that satisfied set criteria and could replace MTA was selected. The microstructure of the prototype material and Portland cement used as a control was assessed after 30 days using SEM and atomic ratio diagrams of Al/Ca versus Si/Ca and S/Ca versus Al/Ca were plotted.
The hydration products of Portland cement replaced with 30% zirconium oxide mixed at water/cement ratio of 0.3 were calcium silicate hydrate, calcium hydroxide and minimal amounts of ettringite and monosulphate. The calcium hydroxide leached in HBSS solution resulted in an increase in the pH value. The zirconium oxide acted as inert filler and exhibited no reaction with the hydration by-products of Portland cement.
A prototype dental material composed of Portland cement replaced with 30% zirconium oxide as radiopacifier leached calcium ions on hydration which reacted with phosphates present in simulated tissue fluids. This resulted in bioactive cement that could prospectively be used as a root-end filling material. The zirconium oxide acted as inert filler and did not participate in the hydration reaction of the Portland cement.
氧化锆可添加到牙科材料中，使其具有足够的射线可透性。因此，它可以替代矿化三氧化物凝聚体（MTA）中的氧化铋。将波特兰水泥与 30%氧化锆混合，水/水泥比为 0.3，制成的材料具有足够的物理性能。本研究旨在研究替代波特兰水泥的氧化锆的微观结构、pH 值和在生理溶液中的浸出率，替代波特兰水泥的氧化锆的水/粉比或水/水泥比分别为 0.3，用作根尖填充材料。评估了表现出最佳性能的材料的水化特性。
以 10%为增量，制备了替代氧化锆的波特兰水泥，替代量从 0%到 50%不等，并将其分为两组。一组按恒定的水/水泥比制备，另一组按恒定的水/粉比 0.3 制备。将波特兰水泥和 MTA 用作对照。用扫描电子显微镜（SEM）分析材料，确定水化产物。用 X 射线能量色散分析（EDX）分析水化产物的元素组成。评估 Hank's 平衡盐溶液（HBSS）中的 pH 值和浸出量。选择一种具有最佳性能且满足设定标准的材料来替代 MTA。使用 SEM 评估原型材料和作为对照的波特兰水泥的微观结构，并绘制 Al/Ca 与 Si/Ca 以及 S/Ca 与 Al/Ca 的原子比图。
水/水泥比为 0.3 的氧化锆替代波特兰水泥的水化产物为硅酸钙水合物、氢氧化钙和少量的钙矾石和单硫酸盐。HBSS 溶液中浸出的氢氧化钙导致 pH 值升高。氧化锆作为惰性填料，与波特兰水泥的水化副产物无反应。
由替代 30%氧化锆的波特兰水泥作为射线阻射剂组成的原型牙科材料在水化过程中浸出钙离子，与模拟组织液中的磷酸盐发生反应。这导致了生物活性水泥，可能有希望用作根尖填充材料。氧化锆作为惰性填料，不参与波特兰水泥的水化反应。
