| Objective To study the effects of the sintering temperature on mechanical properties of nanometer zirconia ceramic abutment material.Methods Nano-side zirconia powder which was produced in Tosoh Ltd. Of Japan was used in the test. Specimens were prepared by dry press method and cold isostatic press method. The specimens were pre-sintered at 1080℃, then were turned and processed. The temperature rise speed of second-sintering was 4℃/min. The temperature of second-sintering was 1350℃,1450℃respectively. The second-sintering was finished after keeping the temperature for 2 hours. Two group specimens were polished and measured. Ten round-slice specimens (15mmx5mm), twenty-two rectangular specimens (1.2mmx4mmx20mm) and ten rectangular specimens (4mmx2mmx25mm) were prepared. Then they were measured on linear shrinkage, sintered density, flexural strength, Vicker's hardness and fracture toughness. The microstructures of fracture surface were tested by scanning microscope, and all the results were analyzed by statistical method.Results①The mechanical properties of two groups were good. Compared with group 1350℃and group 1450℃, with the rising of temperature, all the test results were increased.②The linear shrinkage of group 1450℃was higher than that of group 1350℃(P>0.05)③The sintered density of group 1450℃was higher than that of group 1350℃(P<0.01)④The flexural strength of group 1450℃was higher than that of group 1350℃(P>0.05)⑤The Vicker's hardness of group 1450℃was (16.00±0.42) GPa, it's higher than that of group 1350℃(14.69±0.60) GPa (P<0.01)⑥The fracture toughness of group 1450℃was(6.96±0.55) MPa-m1/2, it's higher than that of group 1350℃(5.43±0.32) MPa-m1/2 (P<0.01)⑦The scanning microscope photos show that zirconia rounded particle was confirmed in group 1450℃and have few stoma; A few disperse stomas were shown in group 1350℃, and the particle was not confirmed enough.Conclusion①When the pre-sintering temperatures of two groups were 1080℃, all the mechanical properties of group 1450℃were higher than group 1350℃.②The twice sintered zirconia specimens have enough mechanical properties to fit the requirement of dental all-ceramic abutment use.
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