Department of Metallurgy and Materials Engineering, Faculty of Engineering, University of Malta, Msida, Malta.
Dent Mater. 2013 Feb;29(2):e11-9. doi: 10.1016/j.dental.2012.11.006. Epub 2012 Nov 27.
One of the challenges encountered with composite restorations is their inability to prevent secondary caries. Alternative fillers that initiate remineralization have been proposed but poor mechanical strength limits their use to lining and support materials. Mineral trioxide aggregate (MTA) is a material with many dental applications including root-end filling and pulp capping. MTA is capable of encouraging remineralization by leaching calcium in solution, and has the ability to form apatite in physiological solution. The aim of this study was to characterize and investigate the chemical properties of MTA-filled composite resins.
Composite resins composed of light-cured (Heliobond) and chemical-cured (Superbond) dental resins filled with MTA Plus (MTA-Light, MTA-Chem) respectively, and MTA Plus mixed with water (MTA-W), were investigated. Un-hydrated and set materials were characterized by scanning electron microscopy (SEM), energy dispersive X-ray (EDX) analysis, X-ray diffraction (XRD) analysis and Fourier transform infrared (FT-IR) spectroscopy after being stored dry or immersed in Hank's balanced salt solution (HBSS). The chemical properties of the set materials were then investigated.
XRD and FT-IR analyses revealed that MTA powder remains unhydrated within the composite, even after 28 days of immersion in HBSS. Furthermore neither resin appeared to chemically react with the MTA. EDX revealed minimal diffusion of bismuth oxide through the polymer network. Apatite formation on the material surfaces was demonstrated by SEM. Significantly less apatite deposition was exhibited on the composites compared to MTA-W. All materials leached calcium and produced an alkaline pH in physiological solution. The pH at 28 days was: MTA-W 12.7, MTA-Light 11.4, and MTA-Chem 10.8. Calcium ion concentration followed the same trend, with MTA-W>MTA-Light>MTA-Chem.
The novel composites exhibited calcium ion release, alkalinizing pH and formation of apatite, although in each case not as strongly as the control (MTA-W). MTA-Chem fared less favorably than MTA-Light in these aspects. Thus they are recommended for applications where bioactivity is desirable but not critical, and only they have a significant advantage over ordinary MTA in some other aspect.
复合修复体面临的挑战之一是其无法预防继发龋。已经提出了替代的可再矿化填料，但较差的机械强度限制了它们作为衬层和支持材料的使用。矿化三氧化物凝聚体（MTA）是一种具有许多牙科应用的材料，包括根尖封闭和牙髓覆盖。MTA 通过浸出溶液中的钙来促进再矿化，并具有在生理溶液中形成磷灰石的能力。本研究的目的是表征和研究填充 MTA 的复合树脂的化学性质。
研究了分别用光固化（Heliobond）和化学固化（Superbond）牙科树脂填充 MTA Plus（MTA-Light、MTA-Chem）以及 MTA Plus 与水混合（MTA-W）的复合树脂。对未水化和凝固材料进行了扫描电子显微镜（SEM）、能量色散 X 射线（EDX）分析、X 射线衍射（XRD）分析和傅里叶变换红外（FT-IR）光谱分析，这些材料在干燥或浸入 Hank's 平衡盐溶液（HBSS）后分别进行了存储。然后研究了凝固材料的化学性质。
XRD 和 FT-IR 分析表明，即使在 HBSS 中浸泡 28 天后，MTA 粉末仍保持在复合材料中未水化。此外，两种树脂似乎都没有与 MTA 发生化学反应。EDX 显示氧化铋通过聚合物网络的扩散很小。材料表面的磷灰石形成通过 SEM 得到证实。与 MTA-W 相比，复合材料的磷灰石沉积明显较少。所有材料都在生理溶液中浸出钙并产生碱性 pH 值。28 天时的 pH 值为：MTA-W 为 12.7，MTA-Light 为 11.4，MTA-Chem 为 10.8。钙离子浓度也呈现出相同的趋势，MTA-W>MTA-Light>MTA-Chem。
新型复合材料表现出钙离子释放、碱化 pH 值和磷灰石形成，尽管在每种情况下都不如对照（MTA-W）强烈。在这些方面，MTA-Chem 的表现不如 MTA-Light。因此，建议将它们应用于需要生物活性但不关键的情况下，并且仅在某些其他方面优于普通 MTA。
