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.

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.

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.

Influence of CAD/CAM Grinding in the Performance of Sintered Dental Zirconia Framework

2012 ◽  
Vol 727-728 ◽  
pp. 1081-1084
Author(s):  
Carlos Nelson Elias ◽  
Andréa Mattos Melo ◽  
Claudinei dos Santos
Keyword(s):  
Mechanical Properties ◽  
High Speed ◽  
Surface Defects ◽  
Tetragonal Zirconia ◽  
Surface Cracks ◽  
Brittle Behavior ◽  
Dental Prostheses ◽  
Cad Cam ◽  
Ceramic Restorations ◽  
Tetragonal Zirconia Polycrystal

The brittle behavior of ceramics limits the use of these materials under conditions of cyclic loading, as is the case of fixed partial dentures. To improve toughness and biocompatibility of ceramics is necessary to employ powders with better purities, adjust the conditions of compaction and sintering, microstructure control and explore mechanisms for increasing the toughness. Yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) is generally used for dental ceramic restorations. The zirconia framework is fabricated using the CAD/CAM system. The ceramic mechanical properties are determined by testing polished sample. Previous work did not analyze the influence of surface defects induced during dentures grinding. Ceramic restorations manufacturing are made with coarse grinding high-speed diamond rotatory cutting instruments. This process induces residual stresses and the high temperature induces surface cracks. Consequently, a lower strength and reliability of the material is observed. In this work the mechanical properties of yttria stabilized zirconia were determined with the use of samples of dental prostheses molded in patients and machined with the use of a dental laboratory CAD/CAM system. The results showed that the mechanical properties of pre-sintered blocks are different from prosthetics machined by CAD/CAM and sintered under the same conditions used in the laboratories of the prosthesis. The defects created during machining reduce the mechanical properties of zirconia.

Measuring Mechanical Properties of Zirconia Dental Crowns by Nanoindentation

2013 ◽  
Vol 591 ◽  
pp. 150-153 ◽  
Author(s):  
Zhao Qiang Meng ◽  
Dan Yu Jiang
Keyword(s):  
Mechanical Properties ◽  
Dental Materials ◽  
Tetragonal Zirconia ◽  
Core Material ◽  
Stiffness Measurement ◽  
High Toughness ◽  
Dental Crowns ◽  
Dental Restorations ◽  
Nanoindentation Testing ◽  
Continuous Stiffness Measurement

Mechanical properties of dental materials are increasingly studied via nanoindentation testing. Due to the excellent mechanical properties, 3-mol%-Yttria-Stabilized Tetragonal Zirconia (3Y-TZP) has become an attractive high-toughness core material for fixed dental restorations. In this paper, the mechanical properties of 3Y-TZP were studied by nanoindentation. The continuous stiffness measurement (CSM) and the single load/unload cycle test controlled by displacement and load respectively were performed with a Berkovich indenter.

scholarly journals Optical properties of translucent zirconia: A review of the literature

2019 ◽  
Vol 3 (1) ◽  
pp. 45-51 ◽  
Author(s):  
Manuela-Maria Manziuc ◽  
Cristina Gasparik ◽  
Marius Negucioiu ◽  
Mariana Constantiniuc ◽  
Alexandru Burde ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Systematic Review ◽  
Optical Properties ◽  
English Language ◽  
Meta Analysis ◽  
Tetragonal Zirconia ◽  
Dental Ceramics ◽  
Monolithic Zirconia ◽  
New Generation

Abstract Translucent monolithic zirconia is the newest option of zirconia-based ceramics, which aimed to substitute the opaque classic yttria-stabilized tetragonal zirconia polycrystal (Y-TZPs) in more demanding esthetic cases. The aim of this review was to assess the available literature regarding the optical, chemical and mechanical properties of translucent zirconia ceramics. This systematic review was developed according to the PRISMA (Preferred Reporting Items for Systematic Review and Meta-analysis) guidelines. An electronic literature search was undertaken through Medline (National Library of Medicine) via PubMed to identify relevant articles, published in the interval 2010-2018. The search was limited to the English language publications, in vitro studies of color and microstructure of translucent zirconia material. Yttria-stabilized tetragonal zirconia polycrystals (Y-TZPs) has excellent mechanical properties, but its intense white color and high opacity represent an esthetic limit. Cubic zirconia represents a new generation of dental ceramics with molecular structure and physical properties different from the conventional zirconia. Dental manufacturers created new formulations of this restorative material, introducing new cubic varieties of zirconia with improved optical properties. Translucent monolithic zirconia provides a new restorative option that combines strength with improved esthetics, due to its increased translucency. Translucent zirconia is indicated for anterior and posterior restorations but should be used carefully for discolored teeth, because the background color can affect the final esthetic appearance of the restoration.

Properties of ZrO2(Y2O3) Used as Metal-Free Dental Restorations

2016 ◽  
Vol 881 ◽  
pp. 181-186
Author(s):  
Claudinei dos Santos ◽  
Carolina Hartung Habibe ◽  
Alexandre Fernandes Habibe ◽  
Roberto de Oliveira Magnago
Keyword(s):  
Fracture Toughness ◽  
Relative Density ◽  
Grain Growth ◽  
Crystalline Phase ◽  
Bending Strength ◽  
Ceramic Materials ◽  
Metal Free ◽  
Dental Restorations ◽  
Dental Prostheses

In this work, pre-sintered zirconia ZrO2(Y2O3) ceramics were characterized aiming its acceptance in standard ISO 6872:2015 (Dentistry-Ceramic Materials). Pre-sintered zirconia blocks were sintered at 1450oC, 1500oC, 1530oC or 1600oC. Sintered samples were sanded, polished and characterized by relative density, crystalline phase, microstructure, hardness, fracture toughness, bending strength, translucence and dilatometry. The results indicated that the ceramic studied presents hardness superior to 1200HV, fracture toughness of 8MPa.m1/2 and bending strength superior to 900MPa. Zirconia sintered at temperature of 1600oC, presented exaggerated grain growth which reduces the material toughness. With the porosity decreasing and the grain growth increasing it happens the increase of translucence, but the mechanical aspects must be analyzed carefully, in order to establish zirconia reliability for using it in dental prostheses.

scholarly journals DFT Study of Electronic Structure and Optical Properties of Kaolinite, Muscovite, and Montmorillonite

Crystals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 618
Author(s):  
Layla Shafei ◽  
Puja Adhikari ◽  
Wai-Yim Ching
Keyword(s):  
Mechanical Properties ◽  
Optical Properties ◽  
Electronic Structure ◽  
Hydrogen Bonds ◽  
Clay Minerals ◽  
Clay Mineral ◽  
Bond Order ◽  
Deep Understanding ◽  
Pharmaceutical Applications ◽  
Structure Properties

Clay mineral materials have attracted attention due to their many properties and applications. The applications of clay minerals are closely linked to their structure and composition. In this paper, we studied the electronic structure properties of kaolinite, muscovite, and montmorillonite crystals, which are classified as clay minerals, by using DFT-based ab initio packages VASP and the OLCAO. The aim of this work is to have a deep understanding of clay mineral materials, including electronic structure, bond strength, mechanical properties, and optical properties. It is worth mentioning that understanding these properties may help continually result in new and innovative clay products in several applications, such as in pharmaceutical applications using kaolinite for their potential in cancer treatment, muscovite used as insulators in electrical appliances, and engineering applications that use montmorillonite as a sealant. In addition, our results show that the role played by hydrogen bonds in O-H bonds has an impact on the hydration in these crystals. Based on calculated total bond order density, it is concluded that kaolinite is slightly more cohesive than montmorillonite, which is consistent with the calculated mechanical properties.

scholarly journals Diffuse approximation for identification of the mechanical properties of microcapsules

2020 ◽  
pp. 108128652097760
Author(s):  
Carlos Quesada ◽  
Claire Dupont ◽  
Pierre Villon ◽  
Anne-Virginie Salsac
Keyword(s):  
Mechanical Properties ◽  
Active Material ◽  
Liquid Core ◽  
Constitutive Law ◽  
Data Driven ◽  
Membrane Properties ◽  
Mechanical Resistance ◽  
Data Set ◽  
Diffuse Approximation ◽  
Capsule Size

A novel data-driven real-time procedure based on diffuse approximation is proposed to characterize the mechanical behavior of liquid-core microcapsules from their deformed shape and identify the mechanical properties of the submicron-thick membrane that protects the inner core through inverse analysis. The method first involves experimentally acquiring the deformed shape that a given microcapsule takes at steady state when it flows through a microfluidic microchannel of comparable cross-sectional size. From the mid-plane capsule profile, we deduce two characteristic geometric quantities that uniquely characterize the shape taken by the microcapsule under external hydrodynamic stresses. To identify the values of the unknown rigidity of the membrane and of the size of the capsule, we compare the geometric quantities with the values predicted numerically using a fluid-structure-interaction model by solving the three-dimensional capsule-flow interactions. The complete numerical data set is obtained off-line by systematically varying the governing parameters of the problem, i.e. the capsule-to-tube confinement ratio, and the capillary number, which is the ratio of the viscous to elastic forces. We show that diffuse approximation efficiently estimates the unknown mechanical resistance of the capsule membrane. We validate the data-driven procedure by applying it to the geometric and mechanical characterization of ovalbumin microcapsules (diameter of the order of a few tens of microns). As soon as the capsule is sufficiently deformed to exhibit a parachute shape at the rear, the capsule size and surface shear modulus are determined with an accuracy of 0.2% and 2.7%, respectively, as compared with 2–3% and 25% without it, in the best cases (Hu et al. Characterizing the membrane properties of capsules flowing in a square-section microfluidic channel: Effects of the membrane constitutive law. Phys Rev E 2013; 87(6): 063008). Diffuse approximation thus allows the capsule size and membrane elastic resistance to be provided quasi-instantly with very high precision. This opens interesting perspectives for industrial applications that require tight control of the capsule mechanical properties in order to secure their behavior when they transport active material.

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