Strength and fracture toughness of zirconia dental ceramics

Turon-Viñas, M.; Anglada, M.

doi:10.1016/j.dental.2017.12.007

Cited by 89 publications

(43 citation statements)

References 36 publications

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“…They are therefore the most promising materials for metal-free dental restorations; however, they also have some issues. Lowtemperature degradation (LTD), or "aging", is wellknown as the main issue for the long-term reliability of zirconia ceramics [5][6][7]9,11,12,[14][15][16][17][18]. Aging is the slow transformation of zirconia crystals from the tetragonal phase to the much more stable monoclinic phase in the absence of mechanical stress.…”

Section: Introductionmentioning

confidence: 99%

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Sintering behavior and mechanical properties of machinable zirconia/mica composites

Taruta

Yamaguchi

Yamakami

et al. 2019

Journal of Asian Ceramic Societies

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In order to fabricate machinable zirconia ceramics for dental restorations, zirconia/mica composites were prepared by mixing zirconia and fine mica powders, compacting the powder mixtures and then conducting pressure-less sintering of green powder compacts. The composites containing 30-49 vol% mica reached approximately full density at 1150ºC. The sintering temperature was 150ºC lower than that of monolithic zirconia. The mica melted during firing at above 1000ºC and recrystallized during cooling. The melting of mica at above 1000ºC induced rearrangement of the zirconia particles and accelerated mass-transport of zirconia through the solution-precipitation, resulting in low-temperature sintering of zirconia. Dense composites containing 30-36 vol% mica were machinable using a drill made of hard metal, while those containing 49 vol% mica were sufficiently machinable with a conventional high-speed steel tool. The machinable composite containing 30 vol% mica had a bending strength of 552 MPa and a fracture toughness of 3.9 MPa•m°5.

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Section: Introductionmentioning

confidence: 99%

“…Most zirconia-based dental restorations are manufactured using a computer-aided design and computer-aided manufacturing (CAD/CAM) technique called "soft machining" [11,12,14,15,18,19]. In this technique, pre-sintered zirconia blanks are machined because fully densified zirconia ceramics are very hard and brittle.…”

Section: Introductionmentioning

confidence: 99%

Sintering behavior and mechanical properties of machinable zirconia/mica composites

Taruta

Yamaguchi

Yamakami

et al. 2019

Journal of Asian Ceramic Societies

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“…The Vicker's hardness for the 4YSZ ceramic sintered at 1200°C (30.3 nm grain size, 96.3% dense) was measured to be 14.2 ± 0.74 GPa. Typical Vicker's indentation hardness of tetragonal zirconia ceramics range from 12‐15 GPa . Vicker's indentation fracture resistance was calculated to be 3.43 ± 0.18 MPa·

\sqrt{m}

(averaged over 18 indents, Figure ) using Palmqvist's equation.…”

Section: Resultsmentioning

confidence: 99%

“…Typical Vicker's indentation hardness of tetragonal zirconia ceramics range from 12-15 GPa. 66,67 Vicker's indentation fracture resistance was calculated to The crack character was not determined in this work, but the crack length to indent length ratio suggested that the Palmqvist crack shape would be more representative for the nanocrystalline zirconia ceramics in this study. Literature values for similar indentation fracture resistance measurements on ultra-fine grained zirconia ceramics range from 2 to 4 MPa· √ m. 67,68 Importantly, both hardness and the indentation fracture resistance fall within the expected range for zirconia ceramics produced, even though the ceramics produced in this work are not fully dense.…”

Section: Properties Of Sintered Nanocrystalline 4ysz Ceramicsmentioning

confidence: 86%

Pressureless low temperature sintering of nanocrystalline zirconia ceramics via dry powder processing

et al. 2019

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Pressureless sintering approaches provide a simple avenue to manufacture dense ceramic parts with minimal processing equipment, but current pressureless sintering techniques have yet to demonstrate capabilities of producing dense ceramics while maintaining sub‐50 nm grain sizes. Nanocrystalline yttria stablized zirconia ceramics were process from 4 mol% yttria stablized zirconia (4YSZ) nanopowders with a crystallite size of 7.5 nm using dry cold isostatic pressing (CIP) where powders are dried immediately prior to green compact formation and CIP vacuum bagging. It is shown that CIP pressures >75 000 psi (517 MPa) effectively remove pores larger than 100 nm and that pressureless sintering occurs at reduced temperatures for green densities ≥50%. Though the sintering kinetics are shown to be similar to other zirconia nanopowder sintering studies, the small initial crystallize size and reduced sintering temperature allowed densities as high as 97.2%, while retaining a ceramic grain size at or below 40 nm. Produced nanocrystalline 4YSZ ceramics with a grain size of 30.3 nm and a density of 96.3% had Vicker's hardnesses as high as 14.2 GPa and Vicker's indentation fracture resistance of 3.43 MPa·m, demonstrating that simple processing approaches can be refined to fabricate nanocrystalline ceramics while maintaining high hardness and indentation fracture resistance.

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“…Zirconia‐based ceramics have high flexural strengths of more than 1000 MPa . This allows their application even for extended fixed partial dentures .…”

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confidence: 99%

Zirconia Primers Improve the Shear Bond Strength of Dental Zirconia

Steiner

Heiss-Kisielewsky

Schwarz

et al. 2019

Journal of Prosthodontics

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Purpose Various resin cements and priming agents are available for adhesive luting of zirconia restorations. The purpose of this study was to investigate how cement type and priming protocol affect the shear bond strength on zirconia ceramics. Materials and Methods Yttria‐stabilized tetragonal zirconia polycrystalline ceramic cylinders were bonded to flat zirconia ceramic surfaces using 7 commercially available resin cements. Ten specimens of each cement group were pretreated with a universal primer, and 10 specimens per group were bonded without pretreatment. In addition, 10 specimens per group were pretreated with system‐specific zirconia primers, which were available for 3 cements. Altogether, 170 bonded specimens were water‐stored, thermal‐cycled, and then submitted to shear bond strength tests. The shear bond strength and the fracture types were documented. Differences in shear bond strengths were assessed using 2‐way ANOVA with post‐hoc test (α = 0.05). A point‐biserial correlation was run between the fracture patterns and the shear bond strengths. Results The mean shear bond strengths of cements in the unprimed group showed large variations between 2.52 ± 3.01 (mean ± SD) MPa and 33.15 ± 7.35 MPa. Pretreating the specimens with a universal primer improved the shear bond strengths significantly in all groups (p < 0.05) with a range of 21.80 ± 12.51 to 57.20 ± 11.40 MPa. The system‐specific primers also improved the shear bond strength significantly, compared to the unprimed group (p < 0.01); however, only one system‐specific primer achieved a shear bond strength superior to the universal primer (p < 0.01). There was also a statistical correlation between the fracture type and the shear bond strength (p < 0.0005), with cohesively fractured specimens showing higher shear bond strengths (37.24 ± 19.87 MPa) than adhesively fractured specimens (23.10 ± 17.65 MPa) (p < 0.001). Conclusion Using universal primer can enhance the maximal shear bond strength of zirconia.

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Strength and fracture toughness of zirconia dental ceramics

Cited by 89 publications

References 36 publications

Sintering behavior and mechanical properties of machinable zirconia/mica composites

Sintering behavior and mechanical properties of machinable zirconia/mica composites

Pressureless low temperature sintering of nanocrystalline zirconia ceramics via dry powder processing

Zirconia Primers Improve the Shear Bond Strength of Dental Zirconia

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