Journal Article イットリア部分安定化ジルコニアの焼成温度と相変態
Relationship between sintering temperature and transformation of phase for Y2O3 partially stabilized zirconia

布田, 博  ,  中島, 三晴  ,  河瀨, 雄治  ,  永澤, 栄  ,  伊藤, 充雄  ,  FUDA, HIROSHI  ,  NAKAJIMA, MITSUHARU  ,  KAWASE, YUJI  ,  NAGASAWA, SAKAE  ,  ITO, MICHIO

41 ( 2 )  , pp.115 - 121 , 2015-12-31 , 松本歯科大学学会
The objective of this study was to verify the stability of Y2O3 partially stabilized zirconia (zirconia) sintered at 1,350℃ and 1,450℃ in a simulated oral environment over a long period of time. After sintering, zirconia was immersed in physiological saline, 1% lactic acid solution, and 1% malic acid solution which can be produced in the oral cavity for 3 or 6 months. The amount of yttrium released, and transformation from the tetragonal phase to monoclinic phase by X–ray diffraction were evaluated. Using X–ray diffraction, the monoclinic phase hardly existed for zirconia sintered at 1,350℃; however, for zirconia sintered at 1,450℃, the monoclinic phase existed. The amount of yttrium released was small after exposure to both 1% lactic acid solution and 1% malic acid solution for zirconia sintered at 1,350℃. In contrast, it showed a maximum relase after exposure for 6 months form zirconia sintered at 1,450℃. Based on the X–ray diffraction, the monoclinic phase did not increase for zirconia sintered at 1,350℃ after exposure to 1% lactic acid solution and 1% malic acid solution for 3 and 6 months. However, there was marked transformation for zirconia sintered at 1,450℃ after exposure for 6 months. The frequency of the monoclinic crystal structures increased with the release of yttrium, as confirmed by the results of X–ray diffraction and measurement. As a result of structural observation, the crystal grain size of zirconia sintered at 1,350℃ was finer than that sintered at 1,450℃. It was clarified that zirconia sintered at 1,350℃ was more suitable than that sintered at 1,450℃ as an implant material.

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