Study on Durability of Dental Adhesive Materials

我们在这里研究牙科粘接材料的耐久性。耐久性的评估是如此重要，它不仅包括粘结强度的退化，而且还包括边缘泄漏、材料本身的退化和磨损性能。牙科复合树脂是最常用的牙科粘接材料。磨损性能是许多临床医生最关心的问题之一。磨损机理包括基质树脂本身的磨损和基质-填料界面降解后填料的脱落。在接下来的几十年里，这些材料的改进将集中在增强基质-填料界面上，因为树脂的增强似乎是如此困难。因此，我们在这里研究了基质-填料界面的退化。首先，通过应用BE…弹性体材料，对模拟口腔环境下磨损机理的磨损试验机进行了改进实验的树脂试件和相对的钢筒之间有更多的夹层。实验证明，该机器可以实现与口腔环境相似的穿戴。为了改进对口腔环境中降解机理的体外模拟，我们进一步尝试在磨损测试之前对树脂试件反复施加机械应力。选用的材料为微填料和树脂嵌体材料。然后我们发现，相当于最终强度的三分之一的高应力和100万倍的高应力并不会导致磨损性能的显著退化。扫描电子显微镜观察也显示磨损表面没有明显差异。结果表明，目前测试的商业材料都得到了很大的改进，干疲劳试验后不会观察到明显的退化。湿疲劳试验可以加速材料的退化。粘接强度的耐久性是粘接树脂水泥最重要的关注点。因此，下一步我们将研制一种适用于水中粘结试件的加载装置。考察了机械应力和环境效应对复合树脂型树脂水泥性能的影响。研究发现，机械效应和环境效应的共同作用是加速胶粘剂强度退化的关键。在没有水环境的情况下单独施加机械应力，或者在没有机械应力的水环境中保持试件，不会导致试件的显著退化。此外，拉应力比剪应力更有利于加速土体的降解。边缘渗漏也是牙科树脂粘固剂的重要问题。因此，我们尝试在上述加载装置上安装用于监测裂纹扩展的试件。我们检查了两种不同类型的粘合剂，并比较了结果，一种是复合树脂型，另一种不含任何填料。在软胶中观察到裂纹的缓慢扩展。另一方面，刚性胶粘剂存在脆性断裂现象。较少

We study here the durability of dental adhesive materials. The evaluation of durability is so important that it includes not only the degradation of adhesive strength but also the marginal leakage, degradation of materials themselves and the wear properties.1. Dental composite resins are the most popular dental adhesive materials. The wear properties are one of the most serious concerns of many clinicians. The mechanism of wear phenomena includes the wear of the matrix resins themseleves and the falling off of fillers after the degradation of matrix-filler interfaces. In coming decades, the improvement of these materials will be focused on the strengthening of the matrix-filler interfaces because the strengthening of resins the organic materials being seemed so difficult. Thus we investigate the degradation of matrix-filler interfaces here. First we improve the wear testing machine which simulates the wear mechanism in the oral environment, by the applications of elastomer materials be … More tween the experimental resin specimens and opposite steel cylinders. It was verified that the wears similar to those in oral environment can be realized by this machine.2. In order to improve the in vitro simulation of the degradation mechanism in the oral environment, we further attempt the repeated application of mechanical stresses to the resin specimens, prior to the wear testings. The materials choosed are the micro-filler type and those for resin-inlay. Then we found that so high stresses as one third of ultimates strength and so many times as 1,000,000 do not induce significant degradation of wear properties. The SEM observation also reveal no significant differences on the wear surfaces. It is concluded that recent commercial materials as tested are so improved that no significant degradation will be observed after the dry fatigue testings. The degradation may be accelerated by the wet fatigue testings.3. The durability of adhesive strength is the most important concerns for adhesive resin cement. Hence next we develop the load application apparatus for the adhesive specimens held in water. The influence of mechanical stresses and environmental effects are examined for the composite resin type resin cements. Then it is found that the simultaneous applications of the mechanical and environmental effect is essential to the acceleration of the adhesive strength degradation. The sole application of mechanical stresses without aqueous environment or the holding of specimens in aqueous environment without mechanical stresses do not induce significant degradation in specimens. Further, the tensile stresses are found to be more effective than the shear stresses for the acceleration of the degradation.4. Marginal leakages also are important problems for dental resin cements. So we try to install the specimens for monitoring crack extensions to the above mentioned load application apparatus. We examined the two distinct types of adhesives and compare the results, the one is composite resin type whereas the other do not contain any fillers. The slow crack extension was observed in the soft adhesives. On the other hand, brittle fracture is observed in rigid adhesives. Less