Fracture Toughness of Posterior Resin Composite Using a Ring Spesimen.

本课题的主要目的是：1）采用环形试样研究浸水时间和热应力对<IC>树脂复合材料和光固化玻璃离子水门汀断裂韧性（K_）的影响; 2）评价填料形状、尺寸和分布对K_的影响<IC>; 3）采用疲劳试验估计树脂复合材料的寿命; 4）采用环形试样研究树脂复合材料K_的影响因素<IC>。几<IC>种市售复合材料在水中贮存1天至1个月或3个月，K值显著下降。热应力复合材料表现出快速下降比水浸的。浸水<IC>时间的延长和热应力的增加对树脂复合材料的K值有显著影响.未<IC>填充树脂的K_值显著较低（0.4MPaROO<m>），而含有球形和粉碎填料的实验树脂复合材料的K_值较高，分别为0.79 ~ 1.06和0.96 ~ 1.30.粉碎填料的树脂复合材料的K值总是显著<IC>高于相应尺寸的球形填料.含有球形填料的树脂复合材料在弹入时迅速产生声发射信号，而含有破碎填料的复合材料声发射信号逐渐增强.填料<IC>粒径对树脂复合材料的K_特性影响较大.光<IC>固化玻璃离子水门汀的K值为0.85 ~ 0.89MPaROO<m>。这些值与微填充树脂复合材料相当。疲劳强度比剪切强度更能准确地反映粘接部位的固位性能。在评价口腔粘接剂的耐久性时，应采用疲劳试验。

The objectives of this research project were 1) to determine the effect of water immersion period and thermal stress on fracture toughness (K_<IC>) of resin composite and light-cured glass ionomer cement using a ring specimen, 2) to evaluate the effect of filler shape, size and distribution on K_<IC>,3) to estimate the longevity of resin composit restorations using a fatigue test, and 4) to investigate the affecting factors on K_<IC> of resin composite using a ring specimen.The results obtained were as follows :1. The K_<IC> values of several commercial composites were decreased significantly from one day to one or three months stored in water. Thermal stressed composites showed a rapid decrease than the water immersed ones. The K_<IC> value of resin composite is significantly affected by prolonging water immersion period and increasing thermal stress.2. The K_<IC> value of unfiled resin was significantly low (0.4 MPaROO<m>) , while the experimental resin composites with both spherical and crushed fillers showed the higher values ranged from 0.79 to 1.06 and from 0.96 to 1.30, respectively.3. Resin composite with crushed filler always showed a significantly higher value of K_<IC> than those with corresponding size of spherical ones.4. The resin composite containing spherical fillers rapidly generated the acoustic emission (AE) signal at the pop in, while gradual increase of AE signal was detected for the composite with crushed fillers.5. The K_<IC> characteristics of resin composite was considerably affected by filler size.6. The K_<IC> values of light-cured glass ionomer cements were ranged from 0.85 to 0.89 MPaROO<m>. These values were comparable to the micro-filled resin composites.7. The fatigue strength reflected the retentive properties of the bonding site more accurately than the shear bond strength. The fatigue test should be utilized when estimating the durability of adhesive restorations in the oral cavity.