Study on Durability of Dental Adhesive Materials

本文研究了齿科胶粘剂材料的耐久性。耐久性的评价是非常重要的，它不仅包括粘接强度的退化，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。磨损机理包括基体树脂本身的磨损和基体-填料界面降解后填料的脱落。在未来的几十年里，这些材料的改进将集中在基体-填料界面的强化上，因为树脂对有机材料的强化似乎很困难。因此，我们在这里研究基体-填料界面的退化。首先，我们改进了模拟口腔环境下磨损机理的磨损试验机，将弹性体材料应用于实验树脂试样与相对钢瓶之间。实验证明，该机器可实现与口腔环境相似的磨损。为了完善口腔环境中降解机制的体外模拟，我们进一步尝试在磨损试验前对树脂试样反复施加机械应力。所选择的材料有微填充型和树脂镶嵌型。然后我们发现，如此高的应力为最终强度的三分之一，以及如此多次的1,000,000，都不会引起磨损性能的显着退化。扫描电镜观察也显示磨损表面无显著差异。结论是，最近的商业材料的测试是如此改进，没有明显的退化将观察到干疲劳试验。湿疲劳试验可能会加速材料的退化。粘接强度的耐久性是粘接树脂水泥最关心的问题。因此，下一步我们开发了粘接试样在水中的加载装置。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。在无水环境下单独施加机械应力或在无机械应力的水环境中保持试样不会引起试样的显著退化。此外，发现拉应力比剪切应力对加速降解更有效。边缘渗漏也是牙用树脂水泥的重要问题。因此，我们尝试将裂缝扩展监测试件安装在上述加载装置上。我们检查了两种不同类型的胶粘剂，并比较了结果，一种是复合树脂型，而另一种不含任何填料。在软粘接剂中观察到缓慢裂纹扩展。另一方面，在刚性胶粘剂中观察到脆性断裂。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