Dental Applications of Low-Temperature Nonthermal Plasmas

2013 ◽  
Vol 10 (3) ◽  
pp. 199-206 ◽  
Author(s):  
Gyoo Cheon Kim ◽  
Hyun Wook Lee ◽  
June Ho Byun ◽  
Jin Chung ◽  
Young Chan Jeon ◽  
...  
Keyword(s):  
Low Temperature ◽  
Nonthermal Plasmas ◽  
Dental Applications

Comparison of the Low Temperature Degradation Properties of Two Y-TZP Ceramics for Dental Applications

2011 ◽  
Vol 492 ◽  
pp. 107-111 ◽  
Author(s):  
Yuan Fu Yi ◽  
Ning Wen ◽  
Xiao Ling Wang ◽  
Long Quan Shao ◽  
Chen Wang
Keyword(s):  
Low Temperature ◽  
Flexural Strength ◽  
Monoclinic Phase ◽  
Surface Microstructure ◽  
Force Microscopy ◽  
Dental Application ◽  
Before And After ◽  
Dental Applications ◽  
Degradation Properties

The purpose of this study was to investigate the influence of in vitro low-temperature degradation (LTD) treatments on the structural stability and mechanical properties of two commercial Y-TZP ceramics candidate for dental application. TZ-3YS and TZ-3YS-E powder were chosen because of there minor differences of chemical composition. The two powders were compacted at 200MPa using cold isostatic pressure, and densely sintered at 1500°C and 1450°C for 2hr respectively. Two methods of in vitro LTD treatments were performed, the first is to autoclave specimens in steam at 134°C, 2bar, for 1 to 5hr; the second is to immerse specimens into 4% acetic acid at 80°C for 168 hr. XRD was used to identify the crystal phases, flexural strength were tested according to ISO 6872 standard, surface microstructure was evaluated by Atomic Force Microscopy (AFM). Results show that the relative content of monoclinic phase was increasing with the prolonged aging time, the TZ-3YS was more sensitive to LTD compared with TZ-3YS-E. LTD tests did not necessary reduce the flexural strength of Y-TZP ceramics, the nucleation and growth of monoclinic phase were detected by AFM, and the surface microstructure induced by LTD was not identical between the two Y-TZP ceramics. AFM was a sensitive method to evaluate the transformation of Y-TZP ceramics. To choose appropriate Y-TZP powder for dental application, it is mandatory to examine the microstructure before and after LTD.

Low Temperature Degradation of Y-TZP Ceramic for Dental Applications

2013 ◽  
Vol 873 ◽  
pp. 241-249
Author(s):  
Zhi Kai Wu ◽  
Ning Li ◽  
Wan Qian Zhao ◽  
Jia Zhen Yan
Keyword(s):  
Low Temperature ◽  
Substantial Reduction ◽  
Tetragonal Zirconia ◽  
Ceramic Materials ◽  
Dental Ceramics ◽  
All Ceramic ◽  
Long Time ◽  
Core Thickness ◽  
Dental Applications

Yttria-stabilized tetragonal zirconia polycrystalline (Y-TZP) ceramic has been recently introduced into prosthetic dentistry for the fabrication of crowns and fixed partial dentures (FPDs). The mechanical properties of Y-TZP are the highest ever reported for the all-ceramic materials. This is favorable for the fabrication of multi-unit posterior bridges and the substantial reduction in core thickness. However, Y-TZP ceramic is susceptible to low temperature degradation (LTD), which is detrimental to the long-time survival and aesthetics of zirconia restorations in vivo. This review summarizes the characterization, mechanisms, and influencing factors of the LTD in dental Y-TZP ceramic. In addition, the recent trend of exploring high aging resistant zirconia-based dental ceramics is discussed.

Preparation of Leucite Powder with Controlled c-Phase Fraction for a Variety of Dental Applications

2007 ◽  
Vol 361-363 ◽  
pp. 897-900
Author(s):  
Alexandra Kloužková ◽  
M. Mrázová ◽  
M. Kohoutková
Keyword(s):  
Particle Size ◽  
Low Temperature ◽  
Dental Materials ◽  
Hydrothermal Conditions ◽  
Preparation Technology ◽  
Low Temperature Preparation ◽  
Main Crystalline Phase ◽  
Materials Used ◽  
Dental Applications ◽  
Temperature Preparation

Leucite (KAlSi2O6) is the main crystalline phase in feldspathic dental materials used for ceramic-fused-to-metal restorations. It occurs in two modifications, low temperature – tetragonal and at temperatures above 600 °C high temperature – cubic modification. The aim of this work was to develop a low-temperature preparation technology of submicron leucite powders with varying ratio of tetragonal and cubic modification. The results show that analcime synthesized in hydrothermal conditions is the suitable precursor for the preparation of leucite with controlled fraction of the c-modification. Homogenous t-leucite having particle size from 2 - 4 μm was prepared by 4h ion-exchange in 4M KCl. Partially stabilized c-leucite was obtained by dual ionexchange; 4h in 4M CsCl led to 48 % of c-modification in the final product.

Low temperature degradation resistant nanostructured yttria-stabilized zirconia for dental applications

2016 ◽  
Vol 42 (7) ◽  
pp. 8190-8197 ◽  
Author(s):  
Ilenia G. Tredici ◽  
Marco Sebastiani ◽  
Federico Massimi ◽  
Edoardo Bemporad ◽  
Alessandro Resmini ◽  
...  
Keyword(s):  
Low Temperature ◽  
Yttria Stabilized Zirconia ◽  
Stabilized Zirconia ◽  
Dental Applications

scholarly journals Yttria Ceria Co-Stabilized Zirconia Reinforced with Alumina and Strontium Hexaaluminate

2019 ◽  
Vol 9 (4) ◽  
pp. 729 ◽  
Author(s):  
Andrea Gommeringer ◽  
Lennart Nölle ◽  
Frank Kern ◽  
Rainer Gadow
Keyword(s):  
Low Temperature ◽  
Bending Strength ◽  
Water Vapor Pressure ◽  
Slip Casting ◽  
Accelerated Ageing ◽  
Stabilized Zirconia ◽  
Strontium Zirconate ◽  
High Fracture ◽  
Different Temperatures ◽  
Dental Applications

Zirconia materials are frequently used in dental applications due to their excellent strength and their tooth-like aspect. Standard yttria stabilized zirconia (Y-TZP) ceramics suffer, however, from moderate toughness and vulnerability to low-temperature degradation. In this study, 1Y6Ce-TZP materials reinforced with different amounts of alumina and/or strontium hexaaluminate were manufactured by slip casting and pressureless sintering at different temperatures to assess their mechanical properties, microstructure, phase composition, and low-temperature degradation stability. Results show that these materials exhibit a high fracture resistance of 10–12 MPa√m, a bending strength between 700–950 MPa, and a Vickers hardness of 1100–1200 HV10. Strontium hexaaluminate (SA6) precipitates were formed in situ by reaction of alumina and strontium zirconate. Although crack deflection at SA6 platelets was clearly visible, a net toughening was not observed. Accelerated ageing tests at 134 °C/3 bar water vapor pressure showed best results for mixed alumina/SA6 reinforcements and a sintering temperature of 1500 °C. Mehl-Avrami-Johnson plots used to describe the ageing kinetics showed clear indications of different ageing mechanisms due to the introduction of the SA6 phase.

Low-temperature degradation of different zirconia ceramics for dental applications

2012 ◽  
Vol 8 (3) ◽  
pp. 1213-1220 ◽  
Author(s):  
Philipp Kohorst ◽  
Lothar Borchers ◽  
Jürgen Strempel ◽  
Meike Stiesch ◽  
Thomas Hassel ◽  
...  
Keyword(s):  
Low Temperature ◽  
Zirconia Ceramics ◽  
Dental Applications

Exsolution and inversion in pigeonite from the Whin Sill, Northern England

1978 ◽  
Vol 36 (1) ◽  
pp. 474-475
Author(s):  
P.P.K. Smith
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Homogeneous Nucleation ◽  
Silicate Mineral ◽  
Antiphase Boundaries ◽  
Two Phase ◽  
Primitive Form ◽  
The Core ◽  
Nucleation Mechanisms ◽  
And Inversion

Grains of pigeonite, a calcium-poor silicate mineral of the pyroxene group, from the Whin Sill dolerite have been ion-thinned and examined by TEM. The pigeonite is strongly zoned chemically from the composition Wo8En64FS28 in the core to Wo13En34FS53 at the rim. Two phase transformations have occurred during the cooling of this pigeonite:- exsolution of augite, a more calcic pyroxene, and inversion of the pigeonite from the high- temperature C face-centred form to the low-temperature primitive form, with the formation of antiphase boundaries (APB's). Different sequences of these exsolution and inversion reactions, together with different nucleation mechanisms of the augite, have created three distinct microstructures depending on the position in the grain.In the core of the grains small platelets of augite about 0.02μm thick have farmed parallel to the (001) plane (Fig. 1). These are thought to have exsolved by homogeneous nucleation. Subsequently the inversion of the pigeonite has led to the creation of APB's.

Low temperature x-ray microanalysis of frozen-hydrated tobacco leaves

1984 ◽  
Vol 42 ◽  
pp. 284-285
Author(s):  
S. Edith Taylor ◽  
Patrick Echlin ◽  
May McKoon ◽  
Thomas L. Hayes
Keyword(s):  
Low Temperature ◽  
Lemna Minor ◽  
Root Tips ◽  
Tobacco Leaves ◽  
X Ray ◽  
Whole Cells ◽  
Carbon Coated ◽  
The Right ◽  
Beam Currents ◽  
The University

Low temperature x-ray microanalysis (LTXM) of solid biological materials has been documented for Lemna minor L. root tips. This discussion will be limited to a demonstration of LTXM for measuring relative elemental distributions of P,S,Cl and K species within whole cells of tobacco leaves.Mature Wisconsin-38 tobacco was grown in the greenhouse at the University of California, Berkeley and picked daily from the mid-stalk position (leaf #9). The tissue was excised from the right of the mid rib and rapidly frozen in liquid nitrogen slush. It was then placed into an Amray biochamber and maintained at 103K. Fracture faces of the tissue were prepared and carbon-coated in the biochamber. The prepared sample was transferred from the biochamber to the Amray 1000A SEM equipped with a cold stage to maintain low temperatures at 103K. Analyses were performed using a tungsten source with accelerating voltages of 17.5 to 20 KV and beam currents from 1-2nA.

Bulk standards for low-temperature biological x-ray microanalysis

1984 ◽  
Vol 42 ◽  
pp. 282-283
Author(s):  
P. Echlin ◽  
M. McKoon ◽  
E.S. Taylor ◽  
C.E. Thomas ◽  
K.L. Maloney ◽  
...  
Keyword(s):  
Phase Separation ◽  
Low Temperature ◽  
Analytical Method ◽  
Salt Solutions ◽  
Absolute Concentration ◽  
Cooling Process ◽  
X Ray ◽  
The Absolute ◽  
Analytical Procedures ◽  
Electrical Conductors

Although sections of frozen salt solutions have been used as standards for x-ray microanalysis, such solutions are less useful when analysed in the bulk form. They are poor thermal and electrical conductors and severe phase separation occurs during the cooling process. Following a suggestion by Whitecross et al we have made up a series of salt solutions containing a small amount of graphite to improve the sample conductivity. In addition, we have incorporated a polymer to ensure the formation of microcrystalline ice and a consequent homogenity of salt dispersion within the frozen matrix. The mixtures have been used to standardize the analytical procedures applied to frozen hydrated bulk specimens based on the peak/background analytical method and to measure the absolute concentration of elements in developing roots.

Field ion microscopy

1988 ◽  
Vol 46 ◽  
pp. 434-435
Author(s):  
Gert Ehrlich
Keyword(s):  
Low Temperature ◽  
Sample Surface ◽  
Low Pressure ◽  
Radius Of Curvature ◽  
Field Ion Microscopy ◽  
Phosphor Screen ◽  
Ion Microscopy ◽  
Field Ion Microscope

The field ion microscope, devised by Erwin Muller in the 1950's, was the first instrument to depict the structure of surfaces in atomic detail. An FIM image of a (111) plane of tungsten (Fig.l) is typical of what can be done by this microscope: for this small plane, every atom, at a separation of 4.48Å from its neighbors in the plane, is revealed. The image of the plane is highly enlarged, as it is projected on a phosphor screen with a radius of curvature more than a million times that of the sample. Müller achieved the resolution necessary to reveal individual atoms by imaging with ions, accommodated to the object at a low temperature. The ions are created at the sample surface by ionization of an inert image gas (usually helium), present at a low pressure (< 1 mTorr). at fields on the order of 4V/Å.

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