Stabilized zirconia as a structural ceramic: An overview☆

Kelly, J. Robert; Denry, Isabelle

doi:10.1016/j.dental.2007.05.005

Cited by 923 publications

(655 citation statements)

References 49 publications

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“…Many studies reported that the major disadvantage of Y-TZP is its reduced stability against low temperature degradation (LTD) [31,[35][36][37][38]. LTD is defined as the spontaneous tetragonal to monoclinic transformation occurring over time at low temperatures, when the transformation is not triggered by the local stress produced at the trip of the advancing crack [2].…”

Section: Discussionmentioning

confidence: 99%

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The effect of zirconia sintering temperature on flexural strength, grain size, and contrast ratio

et al. 2012

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OBJECTIVE: This study investigated the effect of sintering temperatures on flexural strength, contrast ratio, and grain size of zirconia. MATERIALS AND METHODS: Zirconia specimens (Ceramill ZI, Amann Girrbach) were prepared in partially sintered state. Subsequently, the specimens were randomly divided into nine groups and sintered with different final sintering temperatures: 1,300°C, 1,350°C, 1,400°C, 1,450°C, 1,500°C, 1,550°C, 1,600°C, 1,650°C, or 1,700°C with 120 min holding time. Three-point flexural strength (N = 198; n = 22 per group) was measured according to ISO 6872: 2008. The contrast ratio (N = 90; n = 10 per group) was measured according to ISO 2471ISO : 2008. Grain sizes and microstructure of different groups were investigated (N = 9, n = 1 per group) with scanning electron microscope. Data were analyzed using one-way ANOVA with Scheffé test and Weibull statistics (p < 0.05). Pearson correlation coefficient was calculated between either flexural strength or contrast ratio and sintering temperatures. RESULTS: The highest flexural strength was observed in groups sintered between 1,400°C and 1,550°C. The highest Weibull moduli were obtained for zirconia sintered at 1,400°C and the lowest at 1,700°C. The contrast ratio and the grain size were higher with the higher sintering temperature. The microstructure of the specimens sintered above 1,650°C exhibited defects. Sintering temperatures showed a significant negative correlation with both the flexural strength (r = -0.313, p < 0.001) and the contrast ratio values (r = -0.96, p < 0.001). CONCLUSIONS: The results of this study showed that the increase in sintering temperature increased the contrast ratio, but led to a negative impact on the flexural strength. CLINICAL RELEVANCE: Considering the flexural strength values and Weibull moduli, the sintering temperature for the zirconia tested in this study should not exceed 1,550°C. 20]. In fact, the stability of the complete system consisting both the zirconia framework and the veneering ceramic is of clinical importance.In order to decrease the costs and at the same time overcome the chipping problem, it is possible today to produce zirconia FDPs without veneering ceramic.Such monolithic zirconia FDPs require higher translucency with superior mechanical properties especially when they are to be used in the anterior region. Framework translucency is therefore one of the primary factors with respect to aesthetic properties in the selection of dental materials [21,22]. The translucency of dental ceramic is highly dependent on light scattering [23]. When the majority of light passing through a ceramic is intensely scattered and diffusely reflected, the material would appear opaque. However, if only part of the light is scattered and most of it is diffusely transmitted, the material would appear translucent where Y B was the value with a black background, and Y w was the value with a white background. In all calculations, 0 was considered as totally transparent and 1 as

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Section: Discussionmentioning

confidence: 99%

“…This is combined with an increase in the surface roughness [37] resulting possibly in high abrasion of the antagonist enamel. Moreover, through the undesired phase transformation as a result of aging, mechanical properties may decrease further [37,38].…”

Section: Discussionmentioning

confidence: 99%

The effect of zirconia sintering temperature on flexural strength, grain size, and contrast ratio

et al. 2012

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“…The degradation process in aqueous environment is due to corrosion of the ceramic causing growth of small faults (Morena et al, 1986). This is highly important for estimating clinical failures of ceramic restorations (Chevalier, 2006;Kelly and Denry, 2008;Denry and Kelly, 2008). Cyclic fatigue in water was shown to present a high impact on the lifespan of different zirconia materials yielding to significantly lower results than when mechanical cycling was performed in dry conditions (Studart et al, 2007a;Studart et al, 2007b).…”

Section: Discussionmentioning

confidence: 99%

Effect of air-particle abrasion protocols on the biaxial flexural strength, surface characteristics and phase transformation of zirconia after cyclic loading

Özcan

Melo

Souza

et al. 2013

Journal of the Mechanical Behavior of Biomedical Materials

104

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This study evaluated the effect of air-particle abrasion protocols on the biaxial flexural strength, surface characteristics and phase transformation of zirconia after cyclic loading. Disc-shaped zirconia specimens (Ø: 15mm, thickness: 1.2mm) (N=32) were submitted to one of the air-particle abrasion protocols (n=8 per group): (a) 50 m Al2O3 particles, (b) 110 m Al2O3 particles coated with silica (Rocatec Plus), (c) 30 m Al2O3 particles coated with silica (CoJet Sand) for 20s at 2.8bar pressure. Control group received no air-abrasion. All specimens were initially cyclic loaded (×20,000, 50N, 1Hz) in water at 37°C and then subjected to biaxial flexural strength testing where the conditioned surface was under tension. Zirconia surfaces were characterized and roughness was measured with 3D surface profilometer. Phase transformation from tetragonal to monoclinic was determined by Raman spectroscopy. The relative amount of transformed monoclinic zirconia (FM) and transformed zone depth (TZD) were measured using XRD. The data (MPa) were analyzed using ANOVA, Tukey's tests and Weibull modulus (m) were calculated for each group (95% CI). The biaxial flexural strength (MPa) of CoJet treated group (1266.3±158(A)) was not significantly different than that of Rocatec Plus group (1179±216.4(A,B)) but was significantly higher than the other groups (Control: 942.3±74.6(C); 50 m Al2O3: 915.2±185.7(B,C)). Weibull modulus was higher for control (m=13.79) than those of other groups (m=4.95, m=5.64, m=9.13 for group a, b and c, respectively). Surface roughness (Ra) was the highest with 50 m Al2O3 (0.261 m) than those of other groups (0.15-0.195 m). After all air-abrasion protocols, FM increased (15.02%-19.25%) compared to control group (11.12%). TZD also showed increase after air-abrasion protocols (0.83-1.07 m) compared to control group (0.59 m). Air-abrasion protocols increased the roughness and monoclinic phase but in turn abrasion with 30 m Al2O3 particles coated with silica has increased the biaxial flexural strength of the tested zirconia. 942.3±74.6 C ; 50 µm Al 2 O 3 : 915.2±185.7 B,C ). Weibull modulus was higher for control (m=13.79) than those of other groups (m=4. 95, m=5.64, m=9.13 for group a, b and c, respectively). Surface roughness (R a ) was the highest with 50 µm Al 2 O 3 (0.261 µm) than those of other groups (0.15-0.195 µm). After all air-abrasion protocols, F M increased (15.02-19.25%) compared to control group (11.12%). TZD also showed increase after air-abrasion protocols (0.83-1.07 µm) compared to control group (0.59 µm). Air-abrasion protocols increased the roughness and monoclinic phase but in turn abrasion with 30 µm Al 2 O 3 particles coated with silica has increased the biaxial flexural strength of the tested zirconia.

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“…The good combination of fracture toughness and strength of 3Y-TZP allows its employment in a series of applications, which include dental crowns, dental implants, abutments, orthodontic brackets and fixed partial dentures (FPD's) (Conrad et al, 2007;Denry and Kelly, 2008;Kelly and Denry, 2008).…”

Section: Introductionmentioning

confidence: 99%

Surface roughened zirconia: towards hydrothermal stability

Camposilvan

Flamant

Anglada

2015

Journal of the Mechanical Behavior of Biomedical Materials

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Surface roughness is needed in several yttria-stabilized zirconia components used in restorative dentistry for osseointegration or adhesion purposes. This can be achieved by different treatments, which may also modify the microstructure of the surface. Among them, sandblasting and chemical etching are widely used, but their effect on hydrothermal aging of zirconia is not fully understood. In the present work, the zirconia long-term stability of rough surfaces prepared by these techniques is analyzed and a method is proposed for preventing hydrothermal aging while maintaining the original surface appearance and mechanical properties. The method involves pressure infiltration of a Cerium salt solution on the roughened surfaces followed by a thermal treatment. The solution, trapped by surface defects and small pores, is decomposed during thermal treatment into Cerium oxide, which is diffused at high temperature, obtaining Ce co-doping in the near-surface region.In addition, the microstructural changes induced in the near-surface by sandblasting or chemical etching are removed by the thermal treatment together with surface defects. No color modification was observed and the final roughness parameters were in the range of existing implants of proved good osseointegration. The aging resistance of Ce co-doped materials was strongly enhanced, showing the absence of aging after artificial degradation, increasing in this way the surface mechanical integrity.The proposed treatment is easily applicable to the current manufacturing procedures of zirconia dental posts, abutments, crowns and dentures, representing a solution to hydrothermal aging in these and other biomedical applications.

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Stabilized zirconia as a structural ceramic: An overview☆

Cited by 923 publications

References 49 publications

The effect of zirconia sintering temperature on flexural strength, grain size, and contrast ratio

The effect of zirconia sintering temperature on flexural strength, grain size, and contrast ratio

Effect of air-particle abrasion protocols on the biaxial flexural strength, surface characteristics and phase transformation of zirconia after cyclic loading

Surface roughened zirconia: towards hydrothermal stability

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