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

本研究的主要目的是获得在各种机械或化学应力条件下影响氟释放材料的失效和变形以及粘合耐久性的因素的知识，以开发更耐久的口腔氟释放材料。为了实现这一目标，该研究主要集中在表征市售氟化物释放修复材料的失效和变形行为。常规玻璃离聚物随时间增加强度;然而，环境水和酸性气氛使表面纹理劣化。这将降低这些材料的抗破坏性。树脂改性（光固化）的玻璃离聚物表现出更大的机械强度比传统的，因为纳入到基体中的树脂成分。在静载条件下，掺入的树脂组分显著增大了弹性变形和残余变形。牙体在应力作用下的大变形超过了牙体的变形量，这将对牙体材料的耐久性产生不利影响。玻璃离聚物改性的树脂复合材料（复合体）或氟化物可释放的树脂复合材料在研究中检查的氟化物释放材料中的任何条件下显示出最大的强度。这可以从由树脂制成的基体的强度和性质获得。复合体与牙本质的粘接强度在反复加载后降低。与其他材料相比，这些材料显示出最大的抗断裂性时，试样受到反复剪切载荷条件。粘合的耐久性取决于这些材料中使用的粘合处理。由于复合体具有较大的吸水性，复合体和粘合剂之间的粘合强度将是耐久性的关键因素。今后将作进一步调查。

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.