Study on factors affecting the failure, deformation and adhesive durability of fluoride-releasing restorative materials

本研究的主要目的是了解在各种机械或化学应力条件下，影响释氟材料失效变形及粘接耐久性的因素，从而开发出更耐用的口腔释氟材料。为了实现这一目标，研究主要集中在表征市售氟释放修复材料的破坏和变形行为。传统玻璃离聚物的强度随时间增加而增加；然而，周围的水和酸性大气会破坏表面纹理。这将降低这些材料的抗破坏能力。树脂改性（光固化）玻璃离子单体由于在基体中掺入树脂组分而表现出比常规玻璃离子单体更大的机械强度。加入树脂的构件在静载荷条件下的弹性和残余变形显著增大。应力作用下的大变形，超过了牙齿的变形量，会对材料放置在腔内时的耐久性产生负面影响。玻璃离子聚体改性树脂复合材料（复合材料）或可释放氟化物的树脂复合材料在任何条件下都显示出最大的强度。这可以从树脂制成的基体的强度和性能得到。复合材料反复加载后对牛牙本质的粘附强度降低。与其他材料相比，这些材料在反复剪切加载条件下表现出最大的抗断裂能力。粘合的耐久性取决于在这些材料中使用的粘合处理。由于复合材料具有较大的吸水性，因此复合材料与粘结剂之间的粘结强度是影响复合材料耐久性的关键因素。今后将进行进一步调查。

The main goal of this study was to obtain the knowledge in the factors affecting the failure and deformation and the adhesive durability of fluoride-releasing materials under the various mechanical or chemical stress conditions, in order to develop more durable fluoride-releasing materials in the oral cavity. To achieve this goal the study mainly focused to characterize the failure and deformation behavior of commercially available fluoride-releasing restorative materials. Conventional glass ionomers increased strength with time; however, the ambient water and the acidic atmosphere deteriorate the surface texture. This would reduce the failure resistance of these materials. Resin-modified (light-cured) glass ionomers showed larger mechanical strength than the conventional ones because of incorporation of resin components into the matrix. The incorporated resin components notably enlarged elastic and residual deformation under static loading condition. The large deformation under stress, which exceeds the amount of deformation of tooth, would negatively influence the durability of materials when they were placed in the cavities. Glass ionomer-modified resin composites (compomers) or fluoride-releasable resin composite showed the greatest strength under any conditions employed among the fluoride-releasing materials examined in the study. This could be obtained from the strength and properties of the matrix made from resin. The adhesive strength to bovine dentin of compomers reduced after the repeated loading. As compared to other materials, these materials revealed the greatest resistance to fracture when the specimens were subjected to repeated shear loading condition. The durability of adhesion depended upon the bonding treatment used in these materials. Since the compomers have larger water sorption, the bonding strength between the compomer and the bonding agent would be a critical factor for durability. Further investigation will be made in future.