J Adv Prosthodont.  2010 Sep;2(3):81-87. 10.4047/jap.2010.2.3.81.

Sintering behavior and mechanical properties of zirconia compacts fabricated by uniaxial press forming

• Oh GJ
• Yun KD
• Lee KM
• Lim HP
• Park SW

• KMID: 2118111
• DOI: http://doi.org/10.4047/jap.2010.2.3.81

Abstract

PURPOSE
The purpose of this study was to compare the linear sintering behavior of presintered zirconia blocks of various densities. The mechanical properties of the resulting sintered zirconia blocks were then analyzed. MATERIAL AND METHODS: Three experimental groups of dental zirconia blocks, with a different presintering density each, were designed in the present study. Kavo Everest(R) ZS blanks (Kavo, Biberach, Germany) were used as a control group. The experimental group blocks were fabricated from commercial yttria-stabilized tetragonal zirconia powder (KZ-3YF (SD) Type A, KCM. Corporation, Nagoya, Japan). The biaxial flexural strengths, microhardnesses, and microstructures of the sintered blocks were then investigated. The linear sintering shrinkages of blocks were calculated and compared.
RESULTS
Despite their different presintered densities, the sintered blocks of the control and experimental groups showed similar mechanical properties. However, the sintered block had different linear sintering shrinkage rate depending on the density of the presintered block. As the density of the presintered block increased, the linear sintering shrinkage decreased. In the experimental blocks, the three sectioned pieces of each block showed the different linear shrinkage depending on the area. The tops of the experimental blocks showed the lowest linear sintering shrinkage, whereas the bottoms of the experimental blocks showed the highest linear sintering shrinkage.
CONCLUSION
Within the limitations of this study, the density difference of the presintered zirconia block did not affect the mechanical properties of the sintered zirconia block, but affected the linear sintering shrinkage of the zirconia block.

Keyword

Zirconia block; Mechanical properties; Sintering behavior; Linear sintering shrinkage

MeSH Terms

Cyclic N-Oxides
Zirconium
Cyclic N-Oxides
Zirconium

Figure

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  Fig. 1 Schematic illustration of the piston-on-three ball biaxial flexural test device.

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  Fig. 2 Biaxial flexural strength and microhardness data for the experimental groups.

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  Fig. 3 A: Schematic view of the zirconia disc specimen during the flexural strength test. B: SEM images (× 60) of the fractured surface (after the biaxial flexural strength tests) of: a) a control group sample, b) an experimental group sample.

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  Fig. 4 Microstructures of the sintered blocks (× 10,000).

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  Fig. 5 The average densities and linear sintering shrinkage values of the blocks.

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  Fig. 6 The linear sintering shrinkage varied for different regions of the block. *The mean difference is significant at the 0.05 level.

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