scholarly journals Fracture Resistance of Zirconia Oral Implants In Vitro: A Systematic Review and Meta-Analysis

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 562 ◽  
Author(s):  
Annalena Bethke ◽  
Stefano Pieralli ◽  
Ralf-Joachim Kohal ◽  
Felix Burkhardt ◽  
Manja von Stein-Lausnitz ◽  
...  
Keyword(s):  
Dynamic Loading ◽  
Static Loading ◽  
Fracture Resistance ◽  
Tetragonal Zirconia ◽  
Present Review ◽  
Hydrothermal Aging ◽  
Oral Implants ◽  
Electronic Screening ◽  
The Impact ◽  
Zirconia Implants

Various protocols are available to preclinically assess the fracture resistance of zirconia oral implants. The objective of the present review was to determine the impact of different treatments (dynamic loading, hydrothermal aging) and implant features (e.g., material, design or manufacturing) on the fracture resistance of zirconia implants. An electronic screening of two databases (MEDLINE/Pubmed, Embase) was performed. Investigations including > 5 screw-shaped implants providing information to calculate the bending moment at the time point of static loading to fracture were considered. Data was extracted and meta-analyses were conducted using multilevel mixed-effects generalized linear models (GLMs). The Šidák method was used to correct for multiple testing. The initial search resulted in 1864 articles, and finally 19 investigations loading 731 zirconia implants to fracture were analyzed. In general, fracture resistance was affected by the implant design (1-piece > 2-piece, p = 0.004), material (alumina-toughened zirconia/ATZ > yttria-stabilized tetragonal zirconia polycrystal/Y-TZP, p = 0.002) and abutment preparation (untouched > modified/grinded, p < 0.001). In case of 2-piece implants, the amount of dynamic loading cycles prior to static loading (p < 0.001) or anatomical crown supply (p < 0.001) negatively affected the outcome. No impact was found for hydrothermal aging. Heterogeneous findings of the present review highlight the importance of thoroughly and individually evaluating the fracture resistance of every zirconia implant system prior to market release.

scholarly journals Communications and Screening for 2019 Novel Coronavirus at a Tertiary-Care Medical Center

2020 ◽  
Vol 41 (S1) ◽  
pp. s84-s84
Author(s):  
Lorinda Sheeler ◽  
Mary Kukla ◽  
Oluchi Abosi ◽  
Holly Meacham ◽  
Stephanie Holley ◽  
...  
Keyword(s):  
Screening Tool ◽  
Medical Center ◽  
Academic Medical Center ◽  
Tertiary Care ◽  
The United States ◽  
World Health ◽  
Communication Campaign ◽  
Electronic Screening ◽  
Novel Coronavirus ◽  
The Impact

Background: In December of 2019, the World Health Organization reported a novel coronavirus (severe acute respiratory coronavirus virus 2 [SARS-CoV-2)]) causing severe respiratory illness originating in Wuhan, China. Since then, an increasing number of cases and the confirmation of human-to-human transmission has led to the need to develop a communication campaign at our institution. We describe the impact of the communication campaign on the number of calls received and describe patterns of calls during the early stages of our response to this emerging infection. Methods: The University of Iowa Hospitals & Clinics is an 811-bed academic medical center with >200 outpatient clinics. In response to the coronavirus disease 2019 (COVID-19) outbreak, we launched a communications campaign on January 17, 2020. Initial communications included email updates to staff and a dedicated COVID-19 webpage with up-to-date information. Subsequently, we developed an electronic screening tool to guide a risk assessment during patient check in. The screening tool identifies travel to China in the past 14 days and the presence of symptoms defined as fever >37.7°C plus cough or difficulty breathing. The screening tool was activated on January 24, 2020. In addition, university staff contacted each student whose primary residence record included Hubei Province, China. Students were provided with medical contact information, signs and symptoms to monitor for, and a thermometer. Results: During the first 5 days of the campaign, 3 calls were related to COVID-19. The number of calls increased to 18 in the 5 days following the implementation of the electronic screening tool. Of the 21 calls received to date, 8 calls (38%) were generated due to the electronic travel screen, 4 calls (19%) were due to a positive coronavirus result in a multiplex respiratory panel, 4 calls (19%) were related to provider assessment only (without an electronic screening trigger), and 2 calls (10%) sought additional information following the viewing of the web-based communication campaign. Moreover, 3 calls (14%) were for people without travel history but with respiratory symptoms and contact with a person with recent travel to China. Among those reporting symptoms after travel to China, mean time since arrival to the United States was 2.7 days (range, 0–11 days). Conclusion: The COVID-19 outbreak is evolving, and providing up to date information is challenging. Implementing an electronic screening tool helped providers assess patients and direct questions to infection prevention professionals. Analyzing the types of calls received helped tailor messaging to frontline staff.Funding: NoneDisclosures: None

Annual review of research

2003 ◽  
Vol 36 (3) ◽  
pp. 165-189 ◽  
Author(s):  
Richard Johnstone
Keyword(s):  
Information And Communications Technology ◽  
Present Review ◽  
Annual Review ◽  
Communications Technology ◽  
Pedagogical Practice ◽  
Separate Section ◽  
Important Trend ◽  
The Impact

The present review refers to studies published in 2002 in leading research journals. It focuses in particular on learning, teaching and policy in respect of second, modern foreign or additional languages. The comments offered about particular studies are not intended to summarise them (for that, it is best to refer to the actual abstracts which the present journal publishes). What is on offer is a personal selection made because some aspect of a particular article seemed to be of particular interest or to reflect an important trend, and I have attempted to link such elements together to form a narrative. Compared with previous years, two important themes seemed to gather particular momentum in 2002: first, the role of ‘frequency’ in acquisition; and second, the impact of complex and contradictory global factors on everyday pedagogical practice, thinking and attitudes. As in previous years reference is made to the abstracts. Thus, Tarone (2002: 03-158) refers to an article by Tarone published in 2002 and reflected in the 2003 series of this journal as abstract 158. In previous years I have discussed ICT (information and communications technology) in a separate section of its own but this has now been integrated into other sections, reflecting a process of ‘normalisation’.

Putative neural consequences of captivity for elephants and cetaceans

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Bob Jacobs ◽  
Heather Rally ◽  
Catherine Doyle ◽  
Lester O’Brien ◽  
Mackenzie Tennison ◽  
...  
Keyword(s):  
Basal Ganglia ◽  
Behavioral Health ◽  
Negative Impact ◽  
Well Being ◽  
Present Review ◽  
Large Mammals ◽  
Impoverished Environment ◽  
Neural Underpinnings ◽  
The Impact ◽  
The Brain

Abstract The present review assesses the potential neural impact of impoverished, captive environments on large-brained mammals, with a focus on elephants and cetaceans. These species share several characteristics, including being large, wide-ranging, long-lived, cognitively sophisticated, highly social, and large-brained mammals. Although the impact of the captive environment on physical and behavioral health has been well-documented, relatively little attention has been paid to the brain itself. Here, we explore the potential neural consequences of living in captive environments, with a focus on three levels: (1) The effects of environmental impoverishment/enrichment on the brain, emphasizing the negative neural consequences of the captive/impoverished environment; (2) the neural consequences of stress on the brain, with an emphasis on corticolimbic structures; and (3) the neural underpinnings of stereotypies, often observed in captive animals, underscoring dysregulation of the basal ganglia and associated circuitry. To this end, we provide a substantive hypothesis about the negative impact of captivity on the brains of large mammals (e.g., cetaceans and elephants) and how these neural consequences are related to documented evidence for compromised physical and psychological well-being.

Fracture Resistance Behaviors of Titanium‐Zirconium and Zirconia Implants

2021 ◽  
Author(s):  
Brenda Hanes ◽  
Sabrina Feitosa Sochacki ◽  
Kamolphob Phasuk ◽  
John A. Levon ◽  
Dean Morton ◽  
...  
Keyword(s):  
Fracture Resistance ◽  
Titanium Zirconium ◽  
Zirconia Implants

Theoretical and experimental studies of impact energy and rock-drilling efficiency in vibro-impact drilling

2021 ◽  
pp. 1-17
Author(s):  
Quan Cao ◽  
Huaizhong Shi ◽  
Weiqiang Xu ◽  
Chao Xiong ◽  
Zhaoliang Yang ◽  
...  
Keyword(s):  
Dynamic Loading ◽  
Impact Energy ◽  
Penetration Rate ◽  
Experimental Studies ◽  
Impact Frequency ◽  
Optimal Frequency ◽  
Rock Drilling ◽  
Loading Waveform ◽  
Impact Parameters ◽  
The Impact

Abstract Vibro-impact drilling has been proven to be a viable technique for enhancing the Rate of Penetration (ROP) in deep and ultra-deep well drilling. It is essential to study the effects of impact parameters on impact energy and rock-drilling efficiency for impact tool design and operating parameter optimization. In this paper, the influences of impact parameters including impact frequency, dynamic loading amplitude and loading on impact energy were analyzed by theoretical method. Then a full-scale drilling experiment was conducted to study the rock-drilling efficiency. The results are as follows: the optimal frequency is higher than the resonance frequency of the rock. The impact energy increase with the dynamic loading amplitude. The penetration rate at dynamic loading amplitude of 4 KN (0.13137 mm/s) is 38.7% higher than that of 2 KN (0.09473mm/s). When the impact frequency is lower than150 Hz, the rock-drilling efficiency increases with the impact frequency and dynamic loading amplitude. The penetration rate is 0.1051 mm/s at impact frequency of 150 Hz, which is 29.8% higher than that of 10 Hz. The impact energy and penetration rate at square loading waveform are the largest. The impact energy per second at loading waveform of square, sine and triangular is 19.6 J, 12 J and 7.91 J respectively when the impact frequency is set to optimal frequency of impact energy. This study provides a theoretical guidance for the optimization design of vibro-impact drilling technology.

scholarly journals Wetting transition of ionic liquids at metal surfaces: A computational molecular approach to electronic screening using a virtual Thomas-Fermi fluid

2020 ◽  
Author(s):  
Alexander Schlaich ◽  
Dongliang Jin ◽  
Lyderic Bocquet ◽  
Benoit Coasne
Keyword(s):  
Ionic Liquids ◽  
Energy Storage ◽  
Electrostatic Interactions ◽  
Debye Length ◽  
Wetting Transition ◽  
Molecular Fluids ◽  
Thomas Fermi ◽  
Electronic Screening ◽  
Novel Approach ◽  
The Impact

Abstract Of particular relevance to energy storage, electrochemistry and catalysis, ionic and dipolar liquids display a wealth of unexpected fundamental behaviors – in particular in confinement. Beyond now well-documented adsorption, overscreening and crowding effects1,2,3, recent experiments have highlighted novel phenomena such as unconventional screening4 and the impact of the electronic nature – metallic versus insulating – of the confining surface on wetting/phase transitions5,6. Such behaviors, which challenge existing theoretical and numerical modeling frameworks, point to the need for new powerful tools to embrace the properties of confined ionic/dipolar liquids. Here, we introduce a novel atom-scale approach which allows for a versatile description of electronic screening while capturing all molecular aspects inherent to molecular fluids in nanoconfined/interfacial environments. While state of the art molecular simulation strategies only consider perfect metal or insulator surfaces, we build on the Thomas-Fermi formalism for electronic screening to develop an effective approach that allows dealing with any imperfect metal between these asymptotes. The core of our approach is to describe electrostatic interactions within the metal through the behavior of a `virtual' Thomas-Fermi fluid of charged particles, whose Debye length sets the Thomas-Fermi screening length λ in the metal. This easy-to-implement molecular method captures the electrostatic interaction decay upon varying λ from insulator to perfect metal conditions, while describing very accurately the capacitance behavior – and hence the electrochemical properties – of the metallic confining medium. By applying this strategy to a nanoconfined ionic liquid, we demonstrate an unprecedented wetting transition upon switching the confining medium from insulating to metallic. This novel approach provides a powerful framework to predict the unsual behavior of ionic liquids, in particular inside nanoporous metallic structures, with direct applications for energy storage and electrochemistry.

scholarly journals Fracture resistance and 3D finite element analysis of machined ceramic crowns bonded to endodontically treated molars with two planes versus flat occlusal preparation designs: an in vitro study

F1000Research ◽  
2021 ◽  
Vol 8 ◽  
pp. 1020
Author(s):  
Omnia Nabil ◽  
Carl Hany Halim ◽  
Ashraf Hassan Mokhtar
Keyword(s):  
Stress Distribution ◽  
Fracture Resistance ◽  
Element Analysis ◽  
3D Finite Element ◽  
Mean Values ◽  
Group I ◽  
Group Ii ◽  
The Impact ◽  
Preparation Design ◽  
Distribution Of Stresses

Background: The flat occlusal preparation design (FOD) of posterior teeth offers promising results of fracture resistance and stress distribution, but its application in vital teeth is limited as there may be a danger of pulp injury. Although this danger is omitted in endodontically treated teeth, there is no research work assessing the impact of FOD on the fracture resistance and distribution of stresses among these teeth. The aim of this study was to assess the impact of FOD of endodontically treated molars on the fracture resistance and distribution of stresses among a ceramic crown-molar structure when compared to the two planes occlusal preparation design (TOD). Methods: 20 human mandibular molars were endodontically treated and distributed equally to two groups: Group I (TOD) and Group II (FOD). Ceramic CAD/CAM milled lithium disilicate (IPS e.max CAD) crowns were produced for all preparations and adhered using self-adhesive resin cement. Using a universal testing machine, the fracture resistance test was performed. The fractured samples were examined using a stereomicroscope and scanning electron microscope to determine modes of failure. Stress distribution was evaluated by 3D finite element analysis, which was performed on digital models of endodontically treated mandibular molars (one model for each design). Results: Group II recorded statistically non-significant higher fracture resistance mean values (3107.2± 604.9 N) than Group I mean values (2962.6 ±524.27 N) as indicated by Student’s t-test (t=0.55, p= 0.57). Also, Group II resulted in more favorable failure mode as compared to Group I. Both preparation designs yielded low von-Mises stresses within the factor of safety. However, the stress distribution among different layers of the model differed. Conclusions: FOD having comparable fracture strength to TOD and a more favorable fracture behavior can be used for the preparation of endodontically treated molars.

scholarly journals Study of the Dynamic Loading Impact on the Design of Pentices when Sinking Vertical Mine Shafts

2018 ◽  
Vol 41 ◽  
pp. 01016 ◽  
Author(s):  
Vladimir Pershin ◽  
Aleksandr Kopytov ◽  
Fadeev Yuriy ◽  
Wetti Ahmed
Keyword(s):  
Dynamic Loading ◽  
Production Capacity ◽  
Design Parameters ◽  
Structural Elements ◽  
State Technical ◽  
Mine Shaft ◽  
Shaft Sinking ◽  
Reconstruction Project ◽  
Reconstruction Period ◽  
The Impact

Based on the reconstruction project for Gorno-Shorsky branch of JSC “Evrazruda” developed by JSC “Giproruda” to maintain the enterprise’s production capacity of 6 million tons per year, the shaft “Skipovoy” should be sunk from the level of 115 m to the level of 85 m. Due to the fact that the reconstruction period was to be shortened, the employees of LLC “SibGorComplex Engineering” together with the Underground and Mine Construction Department of T.F. Gorbachev Kuzbass State Technical University developed several variants of new design of wedge pentices for vertical mine shaft sinking under hoisting operations. The results of studies of the dynamic loading impact on the design of safety devices in skip shaft sinking are presented in the article. Based on the method of designing the force action essentials for the emergency skip dumping, the functions allowing determining the value of the impact on the main structural elements of pentices completely bridging over the shaft cross-section that can be used to substantiate the design parameters of new wedge pentices.

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