STUDY ON STRESS INDUCED CORROSION AND LIFETIME OF DENTAL RESIN

本研究旨在阐明影响义齿基托热固化树脂裂纹扩展的因素。为了研究环境溶液及其浓度对三点弯曲试件裂纹扩展的影响，在恒定载荷下测量了引入预裂纹的三点弯曲试件的裂纹扩展。此外，通过测量载荷变化与裂纹扩展的关系，通过观察动态三点弯曲试验时试件侧面出现的裂纹，以及用扫描电子显微镜观察断口，考察了环境溶液存在时裂纹与银纹促进裂纹扩展的关系。结果表明，乙醇和冰醋酸对裂纹扩展有显著的促进作用，且随着浓度的增加，促进作用增强。说明义齿基托树脂在受到咬合应力和酒精饮料、醋盘等环境溶液的共同作用下，容易引发裂纹扩展。动态测试和扫描电子显微镜观察结果表明，裂纹是在裂纹开始扩展之前产生的。这些结果表明，义齿基托的裂纹生长首先是从咬合应力下的银纹产生开始的，其次是环境溶液允许生长到裂纹。

This study has been made to clarify the factors affecting a crack growth of denture base heat cured resin. The crack growth of three point bending specimen introduced the precrack was measured at the constant load to investigate the effects of environmental solutions and its concentrations. Furthermore, the relations between crack and craze promoted the crack growth in the presence of environmental solution have been examined by measuring the relationship between load change and crack growth, by observing the crack appeared on the side surface of specimen during the dynamic three point bending test, and by observing the fracture surface using SEM. As a result, the ethanol and acetic acid promoted the crack growth remarkably, and its effect increased with increasing the concentration. This fact indicated that the denture base resin which received both bite stress and environmental solutions such as alcoholic drink and vinegard dish would initiate the crack growth easily. The experimental results of dynamic test and SEM observation showed that the craze was created before the crack started to grow. These results suggested that the crack growth of denture base was proceeded from the craze creation under the bite stress in the first place, and the environmental solution allowed to grow to crack in the second place.