Yttria Tetragonal Zirconia Biomaterials: Kinetic Investigation

Elshazly, Ezzat S.; El-Hout, S. M.; Ali, M. El-Sayed

doi:10.1016/s1005-0302(11)60070-4

Cited by 33 publications

(11 citation statements)

References 24 publications

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“…In the presence of water from the wet veneering porcelain and high temperature during firing cycles (around 800 C); these microcracks act as stress concentration sites which grow further by migration of water into zirconia lattice starting the tetragonal-tomonoclinic phase transformation which is responsible for 3e5% volume increase [31] and thus, creating compressive stresses within the frameworks. These stresses, together with those caused by (core-veneer) CTEs mismatch, are thought to contribute to the marginal distortion developed during veneering of CAD/ CAM frameworks [33,41]. In the present study, attributing the marginal distortion during veneering of CAD/CAM zirconia frameworks to the [low temperature aging phenomenon together with the mismatch between core and veneer coefficients of thermal expansion] seems to be more reasonable rather than to the contraction forces developed from firing shrinkage of veneering porcelain because the high flexural strength and fracture toughness of zirconia [3] can resist its deformation under contraction forces.…”

Section: Discussionmentioning

confidence: 99%

Marginal adaptation of CAD/CAM zirconia-based crown during fabrication steps

Eldessouky

Salama

Shakal

et al. 2015

Tanta Dental Journal

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Background: Excessive marginal discrepancy of crowns favors the rate of cement dissolution and microleakage that may cause pulpal inflammation. Besides, it may increase plaque retention leading to the onset of periodontal disease. Therefore, this research was carried out to study the effect of fabrication stages and artificial aging on the marginal adaptation of CAD/CAM Zirconia-based crowns which have become increasingly popular among the patients due to their natural esthetics and excellent strength.Purpose: To evaluate the marginal adaptation of CAD/CAM Zirconia-based crowns on their respective prepared teeth during different fabrication stages namely; framework, after veneering, after crown cementation and after thermo-mechanical loading. Materials and methods: A total of twenty zirconia frameworks were fabricated using (Cercon smart ceramics, DeguDent, Germany) manufacturing system, conventionally veneered with (Cercon Ceram kiss, DENSPLY, Germany), cemented with conventional glass ionomer to their corresponding prepared human teeth. The cemented crowns were finally aged through a process of thermo-mechanical cyclic loading. The assessment of vertical marginal gap was performed on the prepared teeth using an optical microscope with image-j software analysis system at 40Â magnification for frameworks, for restorations before and after cementation then, after thermo-mechanical loading. Differences between the vertical gap during fabrication stages and the effect of artificial aging were statistically analyzed using a one-way analysis of variance ANOVA and Independent-samples T test. Results: In this study, the marginal gap increased after every tested stage. The vertical marginal gap recorded its smallest mean value (41.08 ± 3.23 mm) during core stage. A significant increase in the measurement of vertical marginal gap was observed after firing the veneering layer reaching (46.87 ± 3.94 mm). After cementation, the marginal gap was (46.87 ± 4.65 mm). Finally; thermo-mechanical loading corresponding to one year of clinical use was found to cause a significant increase the vertical marginal gap to record its highest value (56.73 ± 7.21 mm).

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Section: Discussionmentioning

confidence: 99%

Marginal adaptation of CAD/CAM zirconia-based crown during fabrication steps

Eldessouky

Salama

Shakal

et al. 2015

Tanta Dental Journal

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“…The ability to preserve the tetragonal phase in PSZ at room temperature leads to favorable mechanical properties, especially a high K I C value. 1…”

mentioning

confidence: 99%

Fracture Toughness of 3Y-TZP Dental Ceramics by Using Vickers Indentation Fracture and SELNB Methods

Moradkhani

Baharvandi²,

Naserifar

2019

J. Korean Ceram. Soc

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The objective of this research is to analyze the fracture toughness of pure and silica co-doped yttria-stabilized tetragonal zirconia polycrystal (3Y-TZP) bioceramics containing 0.1 and 0.2 wt.% of alumina, and sintered at a temperature of 1500 °C. Because of the relatively easy preparation of the test specimens and the high speed of testing, the Vickers indentation fracture (VIF) technique is more frequently used to evaluate the fracture toughness of biomaterials and hard biological tissues. The Young's modulus and hardness values were obtained by means of nanoindentation and indentation methods. The fracture toughness values of 3Y-TZP bioceramics were calculated and analyzed using 15 equations related to the VIF technique, and loadings of 49.03 and 196.13 N with a Vickers diamond. For validation, the results were compared with fracture toughness values obtained by the single-edge laser-notch beam (SELNB) method with an almost atomically sharp laser-machined initial notch.

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“…Têm geralmente temperaturas de fusão bastante elevadas e grande estabilidade química, o que lhes confere uma boa resistência à corrosão. (Elshazly, El-Hout, & Ali, 2011).…”

Section: Lista De Figurasunclassified

“…As medidas da cinética da degradação induzida pela umidade de cerâmicas sinterizadas, obtidas por difração de raios X ou espectroscopia Raman, indicam que no processo de transformação de fase isotérmica, a fração de volume transformada com o tempo pode ser expressa em termos da equação V de Mehl-Avrami-Johnson. (Chevalier et al, 2009), (Elshazly et al, 2011). Compilando dados de diferentes temperaturas, a curva da cinética das transformações tem a forma de "C" em um gráfico tempo-temperatura.…”

Section: Degradação a Baixa Temperatura (Ltd)unclassified

“…A degradação num reator hidrotérmico pode ser considerada um teste acelerado que dá em pouco tempo a quantidade de transformação que pode ocorrer em corpos humanos ao longo dos anos (Elshazly et al, 2011). Na presença de água ou vapor de água a temperaturas relativamente baixas, A zircônia tetragonal sofre transformação para monoclínica.…”

Section: Degradação a Baixa Temperatura (Ltd)unclassified

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Caracterização Das Propriedades Mecânicas De Zircônias Policristalinas Tetragonais Estabilizadas Com Ítria

AMARANTE¹

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Yttria Tetragonal Zirconia Biomaterials: Kinetic Investigation

Cited by 33 publications

References 24 publications

Marginal adaptation of CAD/CAM zirconia-based crown during fabrication steps

Marginal adaptation of CAD/CAM zirconia-based crown during fabrication steps

Fracture Toughness of 3Y-TZP Dental Ceramics by Using Vickers Indentation Fracture and SELNB Methods

Caracterização Das Propriedades Mecânicas De Zircônias Policristalinas Tetragonais Estabilizadas Com Ítria

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