Department of Prosthetic Dentistry and Biomedical Materials Science, Hannover Medical School, 30625 Hannover, Germany.
Acta Biomater. 2010 Dec;6(12):4547-52. doi: 10.1016/j.actbio.2010.07.025. Epub 2010 Jul 23.
Low temperature degradation and mechanical and thermal cycling may decrease the strength of zirconia and jeopardize the long-term success of dental restorations made of this material. The objective of this study was to reveal the influence of different environmental and loading conditions on the strength of 3 mol.% yttria-stabilized polycrystalline tetragonal zirconia (3Y-TZP). A total of 144 disk specimens were produced from each of two 3Y-TZP materials, and subjected to one of the following conditions: (A) no further treatment (control); (B and C) 10⁶ and 5×10⁶ mechanical cycles, respectively, with an upper load limit of 100 N; (D) 10⁴ thermal cycles between 5 and 55°C; (E) 200 days storage in water at 36°C; (F) a successive combination of conditions B, D and E; (G) storage in water at 80°C for 64 days; (H) storage in an autoclave at 134°C for 8 h. Monoclinic phase content was evaluated by X-ray diffraction (XRD) analysis. Specimen strength was determined in a biaxial bending test. The two ceramics exhibited average strengths of 995 and 1239 MPa, respectively. No statistically significant influence of any treatment on strength was demonstrated for either material. However, XRD measurements revealed a substantial increase in monoclinic phase content, from an initial 2% (control) to up to 10%, according to storage conditions. As a consequence of hydrothermal loading a tetragonal to monoclinic phase transformation took place at the surface of the 3Y-TZP materials investigated, but, like thermal and mechanical cycling, this did not lead to significant changes in bulk strength.
低温降解以及机械和热循环可能会降低氧化锆的强度，危及由该材料制成的牙科修复体的长期成功。本研究的目的是揭示不同环境和加载条件对 3mol.%氧化钇稳定四方多晶氧化锆（3Y-TZP）强度的影响。总共从两种 3Y-TZP 材料中的每一种生产 144 个圆盘试件，并将其置于以下条件之一：（A）不进行进一步处理（对照）；（B 和 C）分别进行 10⁶ 和 5×10⁶ 次机械循环，上限载荷为 100N；（D）在 5 和 55°C 之间进行 10⁴ 次热循环；（E）在 36°C 的水中储存 200 天；（F）B、D 和 E 条件的连续组合；（G）在 80°C 的水中储存 64 天；（H）在 134°C 的高压釜中储存 8 小时。通过 X 射线衍射（XRD）分析评估四方相含量。通过双轴弯曲试验确定试件强度。两种陶瓷的平均强度分别为 995MPa 和 1239MPa。没有任何处理对两种材料的强度产生显著影响。然而，XRD 测量显示，根据储存条件，四方相含量从初始的 2%（对照）增加到 10%。由于湿热负荷，研究的 3Y-TZP 材料表面发生了四方相向单斜相的转变，但与热循环和机械循环一样，这并没有导致体相强度发生显著变化。
