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KMID : 0362220100370020095
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Journal of The Korean Research Society for Dental Materials
2010 Volume.37 No. 2 p.95 ~ p.106
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The effect of autoclave treatments on the low temperature degradation of dental zirconia ceramics
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Lee Tae-Hoon
Lee Sang-Hyeok
Choi Jae-Yoon
Her Soo-Bok
Ahn Jin-Soo
Lee Sang-Hoon
Yang Hyeong-Cheol
Lim Bum-Soon
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Abstract
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The aim of this study was to evaluate the effect of autoclave treatments on the phase transformation of dental zirconia ceramics. Four commercially available tetragonal zirconia polycrystals (Cercon Base, CRB; Lava, LAV; ZioCera, ZOC; Rainbow, RAB) and one zirconia/alumina composite (ZirAce, ZRA) were tested. Disk type (10×1 ㎜) of specimens were prepared. For grain size estimations, specimens which were thermally etched at 1500℃ for 1h, were analyzed with SEM. Specimens were autoclave treated at 130℃ for 1, 3, 5, 10, and 15hrs. The phases of specimens were identified by x-ray diffractometer before and after autoclave treatment, and the relative amount of monoclinic phase was calculated. The average grain sizes were approximately 0.43 ㎛ for CRB and ZOC, more than 0.68 ㎛ for LAV and RAB, about 5 ㎛ for ZRA. There were no significant differences in the average grain sizes before and after autoclave treatment for 15hrs. CRB, ZOC and ZRA specimens showed little phase transformation after autoclave treatment for 15hrs (<9%). LAV and RAB, however, showed remarkable phase transformation after autoclave treatment for 5hrs (>20%) and severe phase transformation after autoclave treatment for 10hrs (50%, 44%, respectively). Although LAV and RAB groups showed high monoclinic fraction by autoclave treatments, they were reverse phase transformed by annealing treatment at 1200℃ for 2hrs.
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KEYWORD
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Zirconia, low temperature degradation, ageing, XRD, monoclinic
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