Study on static and dynamic fatigue of dental ceramics in water environment

水环境下牙科陶瓷静动态疲劳研究

• 批准号: 09470423
• 负责人: TAKESHIGE Fumio
• 金额: $ 8.13万
• 依托单位: Osaka University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 1997
• 资助国家: 日本
• 起止时间: 1997 至 1999
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09470423/
• 关键词: Fatigue resistance; Fatigue crack; Dental ceramics; K-value; 疲労; 疲労亀裂進展; セラミックス

The objectives of this study were to propose the fatigue crack propagation test of dental ceramics under the control of the stress intensity factor (K-value) and to investigate the static and/or dynamic fatigue of dental ceramics. The rectangular specimens (29x5x3mm), which were introduced the precrack using bridge compression method before testing, was employed. Fatigue crack propagation tests were accomplished under the control of K-value (frequency 10Hz, load ratio R=0.1, 0.5, 0.8) with the electro-hydraulic fatigue testing machine (EHF-FD01, Shimadzu). Fatigue crack growth rates (da/dN) of three commercial ceramics and two commercial composites were obtained as a function of the stress intensity factor range (△K) in the air and water environment. Then a fatigue crack growth threshold (△KィイD2thィエD2) was determined according to ASTM E 647-91. After testing we examined microstructural features of fatigue fracture surfaces by SEM, and then also evaluated the degradation of the marginal area and crack propagation of fired ceramic inlay restorations consisting of a feldspathic porcelain system after 8years in vivo. In the water environment, △KィイD2thィエD2 of ceramics were lower than that in the air, although △KィイD2thィエD2 of composites in the water were higher than in the air. Dynamic fatigue dominated the fatigue of the dental ceramics in the air, and static fatigue was accelerated in the water environment. Microstructural examination of fatigue fracture surfaces showed that the fatigue surfaces were more rough than unstable-fractured surfaces. Crack deflection and crack bridging might increase fatigue resistance of ceramics. Fatigue crack propagation tests could be carried out stably with the precise control of K-value. The m of dental ceramics was very high, and the range of △K in which fatigue crack propagated stably was extremely narrow. Therefore, it was hard to propagate a stable fatigue crack in dental ceramics without control of K-value.

本研究的目的是提出在应力强度因子（K值）控制下的牙科陶瓷疲劳裂纹扩展试验，并研究牙科陶瓷的静态和/或动态疲劳。试验采用29 × 5 × 3 mm的矩形试件，在试验前采用桥式压缩法预裂纹。疲劳裂纹扩展试验在电液疲劳试验机（EHF-FD 01，Shimadzu）上进行，试验条件为K值控制（频率10 Hz，载荷比R=0.1，0.5，0.8）。在空气和水环境中，获得了三种商用陶瓷和两种商用复合材料的疲劳裂纹扩展速率（da/dN）与应力强度因子范围（△K）的关系。然后，根据ASTM E 647-91测定疲劳裂纹扩展阈值（△K ε D 2 th ε D 2）。测试后，我们通过扫描电镜观察了疲劳断口的微观结构特征，然后还评估了在体内8年后，由长方体瓷系统组成的烧结陶瓷嵌体的边缘区域的退化和裂纹扩展。在水环境中，陶瓷的△K_（max）D_（2 th）。牙科陶瓷在空气中的疲劳以动态疲劳为主，在水环境中静态疲劳加速。疲劳断口的显微组织分析表明，疲劳断口比不稳定断口更加粗糙。裂纹偏转和裂纹桥接可提高陶瓷的疲劳抗力。通过对K值的精确控制，可以稳定地进行疲劳裂纹扩展试验。牙科陶瓷的m值很高，疲劳裂纹稳定扩展的△K值范围很窄。因此，如果不控制K值，牙科陶瓷很难扩展稳定的疲劳裂纹。

项目成果

Y. Kawakami et al.: "Fatigue Crack Propagation Test of Ceramics under Control of K-value"Journal of Dental Research. Vol.49 Special Issue (In press). (2000)

Y. Kawakami 等人：“K 值控制下陶瓷的疲劳裂纹扩展试验”牙科研究杂志。

Y.Kawakami et al.: "Fatigue Crack Propagation Test of Ceramics under Control of K-value"Journal of Dental Research. Vol.49 Special Issue(in press). (2000)

Y.Kawakami等人：“K值控制下陶瓷的疲劳裂纹扩展试验”牙科研究杂志。

Y. Kawakami et al: "Fatigue Crack Propagation Test of Ceramics under Control of K-value"Journal of Dental Research. Vol.49, Special Issue (in press). (2000)

Y. Kawakami 等人：“K 值控制下陶瓷的疲劳裂纹扩展试验”牙科研究杂志。

竹重文雄ら: "コンポジットレジンの疲労亀裂進展" 日本歯科保存学雑誌. 40巻 秋季特別号. 110 (1997)

Fumio Takeshige 等人：“复合树脂中的疲劳裂纹扩展”，日本保守牙科杂志，第 40 卷，秋季特刊（1997 年）。

F.Takeshige et al: "Sensitivity of Fatigue Crack Growth Rate for Degradation of Composites"Journal of Dental Research. Vol.48, Special Issue. 158 (1999)

F.Takeshige 等人：“疲劳裂纹扩展速率对复合材料降解的敏感性”牙科研究杂志。