Yang H, Lu Z C, Yang S, Cheng H, Yu H
Department of Prosthodontics, School and Hospital of Stomatology, Fujian Medical University & Fujian Key Laboratory of Oral Diseases & Fujian Provincial Engineering Research Center of Oral Biomaterial & Stomatological Key Laboratory of Fujian College and University & Institute of Stomatology, Fujian Medical University & Research Center of Dental Esthetics and Biomechanics, Fujian Medical University, Fuzhou 350002, China.
Zhonghua Kou Qiang Yi Xue Za Zhi. 2022 May 9;57(5):516-522. doi: 10.3760/cma.j.cn112144-20210714-00327.
To evaluate the effects of pre-sintering heating rate and powder size on dental recycled zirconia. Recycled zirconia powders were sieved to obtain the large (50 μm<particle diameter≤125 μm) and small (particle diameter≤50 μm) particles, these powders were then formed into green bodies. According to the pre-sintering heating rates, the recycled-zirconia green bodies were divided into 3 groups: group A, pre-sintering heating rate of 2 ℃/min; group B, pre-sintering heating rate of 5 ℃/min; group C, pre-sintering heating rate of 8 ℃/min. The relative density open porosity and machinability of the recycled zirconia pre-sintered bodies were evaluated and compared with the commercial zirconia pre-sintered bodies. Zirconia pre-sintered bodies were then fully sintered according to the manufacturer's instructions. The relative density, open porosity, linear shrinkage and flexural strength of fully sintered zirconia were further compared. The microstructure of fracture surfaces and the crystalline structure were analyzed by scanning electron microscope and X-ray diffractometer, respectively. With the same particle size, the recycled zirconia pre-sintered at different heating rates showed no significant differences in the relative densities, and the open porosities (>0.05). When the pre-sintering heating rates were 2 ℃/min, 5 ℃/min, and 8 ℃/min, the flexural strengths of the large-particle recycled zirconia were (421.2±54.7), (444.2±70.1) and (427.5±68.4) MPa, the flexural strengths of the small-particle recycled zirconia were (750.1±74.1), (777.2±95.5) and (746.7±73.0) MPa, respectively. The flexural strength of commercial zirconia was (988.4±129.8) MPa. The flexural strengths of the recycled zirconia were significantly lower than that of the commercial zirconia (<0.05). At the same pre-sintering heating rate, the flexural strengths of the small-particle recycled zirconia were significantly higher than that of the large-particle recycled zirconia (<0.05). Compared with the large particles, small-particle recycled zirconia powders can effectively improve the properties of recycled zirconia, while the pre-sintering heating rate has no effect on the properties of the recycled zirconia.
评估预烧结加热速率和粉末尺寸对牙科再生氧化锆的影响。将再生氧化锆粉末进行筛分以获得大颗粒（50μm＜粒径≤125μm）和小颗粒（粒径≤50μm），然后将这些粉末制成生坯。根据预烧结加热速率，将再生氧化锆生坯分为3组：A组，预烧结加热速率为2℃/min；B组，预烧结加热速率为5℃/min；C组，预烧结加热速率为8℃/min。对再生氧化锆预烧结体的相对密度、开口孔隙率和可加工性进行评估，并与商用氧化锆预烧结体进行比较。然后按照制造商的说明对氧化锆预烧结体进行完全烧结。进一步比较完全烧结氧化锆的相对密度、开口孔隙率、线性收缩率和抗弯强度。分别通过扫描电子显微镜和X射线衍射仪分析断口的微观结构和晶体结构。在相同粒径下，不同加热速率预烧结的再生氧化锆在相对密度和开口孔隙率方面无显著差异（＞0.05）。当预烧结加热速率分别为2℃/min、5℃/min和8℃/min时，大颗粒再生氧化锆的抗弯强度分别为（421.2±54.7）、（444.2±70.1）和（427.5±68.4）MPa，小颗粒再生氧化锆的抗弯强度分别为（750.1±74.1）、（777.2±95.5）和（746.7±73.0）MPa。商用氧化锆的抗弯强度为（988.4±129.
