Visco-elastic parameters of dental restorative materials during setting
Visco-elastic parameters of dental restorative materials during setting
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DOI：
10.1177/00220345000790030601
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发表时间：
2000-03-01
影响因子：
7.6
通讯作者：
Davidson, CL
中科院分区：
文献类型：
--
作者：
Dauvillier, BS;Feilzer, AJ;Davidson, CL
修复体在固定过程中产生的收缩应力是粘结剂牙科的主要问题之一，因为它们通常会导致洞壁的粘附性丧失或术后疼痛。应力发展速度和最终应力大小决定了这些问题的严重性，取决于修复体在固位过程中相对未知的粘弹性行为。本研究的目的是确定在设置过程中的粘弹性参数，以帮助我们了解收缩应力的发展过程。采用动态力学方法，在万能试验机上对材料在凝结前60min进行周期性应变循环，利用Maxwell建立的简单力学模型，通过对实验应力-应变数据的分析，计算出粘弹性参数(粘度ETA和杨氏模数E)。研究了两种不同类别的修复材料：双糊状树脂复合体和普通玻璃离子水门汀。比较结果表明，在凝结的早期阶段，粘度和硬度的发展存在显著差异。玻璃离子的松弛时间(ETA/E)在前15分钟内保持在较低水平，而树脂复合材料的松弛时间显著增加。这一点具有临床重要性，因为它意味着，在固化的早期阶段，玻璃离子比树脂复合材料能够更好地降低收缩应力，从而增加了与洞壁的粘结在固化过程中形成并存活的可能性。
Contraction stresses generated in restoratives during setting are among the major problems in adhesive dentistry, since they often result in loss of adhesion from the cavity walls or in post-operative pain. The rate of stress development and the ultimate magnitude of the stress, which determine the seriousness of these problems, depend on the relatively unknown visco-elastic behavior of the restoratives during setting. The aim of this study was to determine the visco-elastic parameters during setting, to aid our understanding of the process of contraction stress development. A dynamic mechanical method was used in which the materials were subjected to periodic strain cycles in a universal testing machine during the first 60 min of setting, The visco-elastic parameters (viscosity eta and Young's modulus E) were calculated by analysis of the experimental stress-strain data with a simple mechanical model according to Maxwell. Two restorative materials from different classes were investigated: a two-paste resin composite and a conventional glass-ionomer cement. A comparison of the results showed significant differences in the development of viscosity and stiffness in the early stage of setting. The resultant relaxation time (eta/E) of the glass ionomer remained at a low level during the first 15 min, whereas that of the resin composite increased markedly. This is of clinical importance, since it implies that, during the early setting stage, glass ionomers are better capable of reducing the contraction stresses than resin composites, thus increasing the likelihood that the bond with the cavity walls will form and survive during setting.