A Review of the Low-Temperature Degradation of Dental Zirconia

2014 ◽  
Vol 606 ◽  
pp. 85-88
Author(s):  
Mohamed M. Aboras ◽  
Kai Yuan Theng ◽  
Andanastuti Muchtar ◽  
Che Husna Azhari ◽  
Norziha Yahaya
Keyword(s):  
Mechanical Properties ◽  
Optical Properties ◽  
Low Temperature ◽  
Tetragonal Zirconia ◽  
Dental Restoration ◽  
Restorative Material ◽  
Dental Restorations ◽  
Biological Compatibility ◽  
Oral Environment ◽  
Dental Restorative

The use of tetragonal zirconia as a dental restorative material has recently increased because of its unique mechanical and optical properties, as well as high biological compatibility with the oral cavity environment. However, the mechanical properties of zirconia can be severely degraded, which leads to the failure of dental restorations. This review focuses on the low-temperature degradation of dental zirconia and its effects on the properties of zirconia and on the oral environment. The purpose is to show the importance of this negative phenomenon and suggest guidelines for minimizing the aging of zirconia that is used as a dental restoration material.

Type of Failure of Zirconia-Based Ceramics in Dental Laboratory in Misurata, Libya

2014 ◽  
Vol 575 ◽  
pp. 22-25
Author(s):  
Mohamed M. Aboras ◽  
A. Muchtar ◽  
C.H. Azhari ◽  
N. Yahaya
Keyword(s):  
Mechanical Properties ◽  
Core Material ◽  
Restorative Material ◽  
Suitable Material ◽  
Dental Restorations ◽  
Type Of Failure ◽  
Dental Restorative ◽  
Failure Types

Zirconia (ZrO2) is used to fix restorations as a core material because of its mechanical properties, aesthetics, and compatibility. This study aims to analyze the failure types in ZrO2-based restoration fabricated in a dental laboratory in Misurata, Libya. Data were collected from laboratory records for a 30-day period with follow-up for five months. About 6% of the total restorations had defects with different percentages, 46% of which were fractures, 29% of which had weak bonding between ZrO2frameworks and veneers, 18% of which had cracks, and 7% of which had shade defects. Although ZrO2is a suitable material for dental restorations, defects may occur and lead to the failure of dental restorations. A thorough study is necessary to analyze the cause of failurein zirconia-based restorationsand to improve the properties to produce a versatile dental restorative material.

ZrO2 Pre-Sintered Blocks (3%mol-Y2O3) with Color Gradient for Dental Prostheses

2018 ◽  
Vol 930 ◽  
pp. 57-62
Author(s):  
Rodrigo Xavier de Freitas ◽  
Claudinei dos Santos ◽  
Bruno Xavier de Freitas ◽  
Bruno Galvão Simba
Keyword(s):  
Mechanical Properties ◽  
Optical Properties ◽  
Tetragonal Zirconia ◽  
Cervical Region ◽  
Mechanical Resistance ◽  
Metal Free ◽  
Dental Restorations ◽  
Dental Prostheses ◽  
Aesthetic Results ◽  
Color Gradient

In dentistry, metal-free ceramic systems are used to improve optical properties in dental restorations. Ceramics based on tetragonal zirconia ZrO2-Y2O3 are used in the manufacturing of dental prostheses for being biocompatible and for presenting proper mechanical and optical properties. Most of tetragonal zirconia blocks are commercialized in one only hue, which difficult the achievement of high aesthetic performance due to the tooth’s polychromatic characteristics. This work proposes to obtain tetragonal zirconia blocks fabricated by uniaxial cold pressing in different hues which could provide ceramic prostheses with better aesthetic results in less time. Zirconia blocks in two different colors were produced and characterized for their physical properties and mechanical resistance. The colors difference between the layers was obtained by using different amounts of Fe2O3. Ceramics with relative density superior to 99% were obtained by sintering the materials at 1530oC for 120 minutes. The mechanical properties evaluated indicated hardness close to 1270HV and fracture toughness of 7MPa.m1/2. Blocks with different hues may be an alternative in order to favor the aesthetics in the cervical region and decrease the amount of ceramic veneering.

Characterization of NiCrMo Dental Restoration Alloy

2021 ◽  
Vol 875 ◽  
pp. 373-378
Author(s):  
Ali Haider ◽  
Omar Farooq Azam ◽  
Muhammad Talha ◽  
Saleem Akhtar
Keyword(s):  
Mechanical Properties ◽  
Corrosion Resistance ◽  
Dental Materials ◽  
Dental Restoration ◽  
Restorative Material ◽  
Nicr Alloy ◽  
In Vitro Biocompatibility ◽  
Dental Prostheses ◽  
Materials Used

Restorative material is a class of dental materials used for direct filling and fabrication of indirect restoration. NiCr alloy is a restorative material frequently used for dental prostheses due to its properties and economic reasons. In present work beryllium free NiCrMo alloy was developed and studied for dental restoration application. The alloy have unique characteristics of resistance to oxidation and biocompatibility; the requisites for dental prostheses. NiCrMo alloy is found to possess mechanical strength and fabrication properties suitable for dental repairs. In this study the developed alloy was tested for its mechanical properties, biocompatibility and corrosion resistance. An in-vitro biocompatibility study was carried out. No signs of toxicity and no signs of cell growth inhibition, in presence of NiCrMo alloy specimen, were observed. Mechanical properties and corrosion resistance are found in the range that is suitable for dental prostheses and easy fabrication.

CAD/CAM Zirconia for Dental Application

2013 ◽  
Vol 320 ◽  
pp. 505-511
Author(s):  
Ning Li ◽  
Zhi Kai Wu ◽  
Chao Jian ◽  
Wan Qian Zhao ◽  
Jia Zhen Yan
Keyword(s):  
Mechanical Properties ◽  
Low Temperature ◽  
Key Words ◽  
20Th Century ◽  
Dental Materials ◽  
Tetragonal Zirconia ◽  
Dental Application ◽  
Cad Cam ◽  
Low Temperature Aging ◽  
Temperature Aging

During the 20th century, both dental materials and dental technologies for the fabrication of dental prosthesis progressed remarkably. Owing to the increased demand of safety and aesthetics, 3 mol% yttria stabilized tetragonal zirconia polycrystalline has been recently introduced in prosthetic dentistry for the fabrication of crowns and fixed partial dentures, in combination with CAD/CAM technique. This greatly changed the conventional dental laboratory work which is labor-intensive and experience-dependent. This review mainly introduced the state of dental zirconia and the application of CAD/CAM technology in dentistry. Key words: Dental Zirconia; CAD/CAM Technique; Mechanical Properties; Transformation Toughing; Low Temperature Aging;

Effect of Sintering Temperature on the Mechanical Properties of Nanostructured Ceria-Zirconia Prepared by Colloidal Process

2015 ◽  
Vol 1125 ◽  
pp. 401-405
Author(s):  
Mohamed M. Aboras ◽  
Andanastuti Muchtar ◽  
Noor Faeizah Amat ◽  
Che Husna Azhari ◽  
Norziha Yahaya
Keyword(s):  
Mechanical Properties ◽  
Sintering Temperature ◽  
Slip Casting ◽  
Tetragonal Zirconia ◽  
Cold Isostatic Pressing ◽  
Sintering Process ◽  
Colloidal Processing ◽  
Tooth Color ◽  
Biological Compatibility ◽  
Nanostructured Ceria

The demand for tetragonal zirconia as a dental restorative material has been increasing because of its excellent mechanical properties and resemblance to natural tooth color, as well as its excellent biological compatibility. Cerium oxide (CeO2) has been added to yttria-stabilized zirconia (Y-TZP), and studies have demonstrated that the stability of the tetragonal phase can be significantly improved. Y-TZP with 5wt% CeO2 as a second stabilizer was developed via colloidal process, followed by a suitable sintering process. According to the literature, the sintering process is the most crucial stage in ceramic processing to obtain the most homogeneous structure with high density and hardness. This study aims to investigate the effect of sintering temperature on the mechanical properties of nanostructured ceria–zirconia fabricated via colloidal processing and slip casting process with cold isostatic pressing (CIP). Twenty-five pellet specimens were prepared from ceria–zirconia with 20 nm particle size. CeO2 nanopowder was mixed with Y-TZP nanopowder via colloidal processing. The consolidation of the powder was done via slip casting followed by CIP. The samples were divided into five different sintering temperatures with. Results from FESEM, density and hardness analyses demonstrated statistically significant increase in density and hardness as the sintering temperature increased. The hardness increased from 4.65 GPa to 14.14 GPa, and the density increased from 4.70 to 5.97 (g/cm3) as the sintering temperature increased without changing the holding time. Sintering Ce-Y-TZP at 1600 °C produced samples with homogenous structures, high hardness (14.14 GPa), and full densification with 98% of the theoretical density.

Mechanical Properties of Zirconia/Alumina Nano-Composite after Soaking in Various Water-Based Conditions

2006 ◽  
Vol 309-311 ◽  
pp. 1219-1222 ◽  
Author(s):  
Seiji Ban ◽  
Masahiro Nawa ◽  
Y. Suehiro ◽  
H. Nakanishi
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Tetragonal Zirconia ◽  
Flexure Strength ◽  
Nano Composite ◽  
Dental Restorations ◽  
Dental Restoratives ◽  
All Ceramic ◽  
Water Based ◽  
Before And After

Yttria stabilized tetragonal zirconia polycrystals (Y-TZP) have been applied to dental crown and bridges. Whereas, to further improve its mechanical strength, the zirconia/alumina nano-composite stabilized with cerium oxide (Ce-TZP/Al2O3 nano-composite) was developed. In the present study, biaxial flexure strength, fracture toughness and hardness were determined before and after soaking in water-based conditions and the possibility of application to all ceramic dental restorations was discussed. In comparison to Y-TZP, Ce-TZP/Al2O3 nano-composite has quite high flexure strength and fracture toughness along with satisfied durability for LTAD in various water-based conditions encountered in dentistry. Therefore, it is concluded that the nano-composite can be safely applied to dental restoratives such as all-ceramic bridges.

Mechanical properties and low-temperature aging of tetragonal zirconia polycrystals processed by hot isostatic pressing

2003 ◽  
Vol 18 (10) ◽  
pp. 2415-2426 ◽  
Author(s):  
J. Muñoz-Saldaña ◽  
H. Balmori-Ramírez ◽  
D. Jaramillo-Vigueras ◽  
T. Iga ◽  
G. A. Schneider
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Low Temperature ◽  
Hot Isostatic Pressing ◽  
Tetragonal Zirconia ◽  
Hot Water ◽  
Full Density ◽  
Isostatic Pressing ◽  
Low Temperature Aging ◽  
Temperature Aging

The influence of grain size and density of yttria-tetragonal zirconia polycrystals (Y-TZPs) ceramics on mechanical properties and on low-temperature aging degradation (LTD) in air and in hot water was investigated. A TZP powder containing 3 mol% Y2O3 was consolidated by slip casting and densified by the sintering/hot isostatic pressing (HIP) method. Only the presintered samples that contained less than 0.15% open porosity reached near full density after HIP. The best conditions to reach full density were found to be attained by presintering and HIP both at 1400 °C. At these conditions, some of the best mechanical properties such as modulus of rupture and Weibull modulus reached 1397 ± 153 MPa and, 10.6, respectively. These values were clearly higher than those obtained from sintered bodies and samples hot isostatically pressed at 1600 °C. Aging degradation of 3Y-TZP materials can be avoided through microstructural design. Fully dense materials with a critical grain size <0.36 μm did not show any evidence of degradation after extreme aging conditions at pressurized autoclaving in hot water at 100, 200, and 260 °C for 8 h. We propose a criterion to predict degradation in air as well as in hot water for the characterized materials based on the microstructure and density control of the samples.

Mechanical properties of low-temperature sintered ceria-stabilized tetragonal zirconia phase Part III Thermal shock resistance

1993 ◽  
Vol 12 (9) ◽  
pp. 684-686 ◽  
Author(s):  
R. Ponraj ◽  
V. E. Annamalai ◽  
S. Ramakrishna Iyer ◽  
C. V. Gokularathnam ◽  
R. Krishnamurthy
Keyword(s):  
Mechanical Properties ◽  
Low Temperature ◽  
Thermal Shock ◽  
Thermal Shock Resistance ◽  
Tetragonal Zirconia ◽  
Shock Resistance ◽  
Zirconia Phase

scholarly journals The Influence of Surface Preparation, Chewing Simulation, and Thermal Cycling on the Phase Composition of Dental Zirconia

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2133
Author(s):  
Markus Wertz ◽  
Florian Fuchs ◽  
Hieronymus Hoelzig ◽  
Julia Maria Wertz ◽  
Gert Kloess ◽  
...  
Keyword(s):  
Phase Composition ◽  
Rietveld Method ◽  
Tetragonal Zirconia ◽  
Surface Preparation ◽  
Dental Restoration ◽  
X Ray Diffraction ◽  
X Ray ◽  
Chewing Simulation ◽  
Yttria Content ◽  
Dental Restorative

The effect of dental technical tools on the phase composition and roughness of 3/4/5 yttria-stabilized tetragonal zirconia polycrystalline (3y-/4y-/5y-TZP) for application in prosthetic dentistry was investigated. Additionally, the X-ray diffraction methods of Garvie-Nicholson and Rietveld were compared in a dental restoration context. Seven plates from two manufacturers, each fabricated from commercially available zirconia (3/4/5 mol%) for application as dental restorative material, were stressed by different dental technical tools used for grinding and polishing, as well as by chewing simulation and thermocycling. All specimens were examined via laser microscopy (surface roughness) and X-ray diffraction (DIN EN ISO 13356 and the Rietveld method). As a result, the monoclinic phase fraction was halved by grinding for the 3y-TZP and transformed entirely into one of the tetragonal phases by polishing/chewing for all specimens. The tetragonal phase t is preferred for an yttria content of 3 mol% and phase t″ for 5 mol%. Mechanical stress, such as polishing or grinding, does not trigger low-temperature degradation (LTD), but it fosters a phase transformation from monoclinic to tetragonal under certain conditions. This may increase the translucency and deteriorate the mechanical properties to some extent.

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