-
Clinical Oral Implants Research Jul 2024To evaluate the effect of different cement types on the incidence of failure and loss of retention of zirconia and metal-ceramic single crowns (SCs) cemented on implant...
OBJECTIVES
To evaluate the effect of different cement types on the incidence of failure and loss of retention of zirconia and metal-ceramic single crowns (SCs) cemented on implant abutments.
METHODS
We placed 567 implant-supported SCs in 358 patients and retrospectively evaluated long-term retention for up to 12.8 years. The frameworks were made from metal alloy (n = 307) or zirconia (n = 260). SCs were cemented with permanent (glass-ionomer cement; n = 376) or semipermanent cement (zinc oxide non-eugenol cement; n = 191) on standardized (n = 446) or customized (n = 121) abutments. Kaplan-Meier curves were used to calculate the incidence of decementation. Differences between survival curves were assessed with log-rank tests. Cox-regression analysis was performed to evaluate multiple risk factors.
RESULTS
Of the 567 SCs, 22 failed because of technical complications and four because of implant loss. Loss of retention was observed in 50 SCs. Analysis revealed a 7% probability of loss of retention for zirconia and 16% for metal-ceramic SCs after 10 years (p = .011). After 5 years, loss of retention was higher for standardized abutments than for customized abutments (p = .014). The probability of loss of retention was higher with semipermanent than with permanent cement (p = .001). Cox-regression analysis revealed semipermanent cement as the only significant risk factor for SC failure (p = .026).
CONCLUSIONS
In contrast to semipermanent cement, permanent cement provides acceptable long-term retention of cemented implant-supported SCs. These possible positive effects of customized abutments have to be controlled with larger sample sizes.
PubMed: 38953431
DOI: 10.1111/clr.14321 -
Small (Weinheim An Der Bergstrasse,... Jul 2024Ammonia fuel cells using carbon-neutral ammonia as fuel are regarded as a fast, furious, and flexible next-generation carbon-free energy conversion technology, but it is...
Ammonia fuel cells using carbon-neutral ammonia as fuel are regarded as a fast, furious, and flexible next-generation carbon-free energy conversion technology, but it is limited by the kinetically sluggish ammonia oxidation reaction (AOR), oxygen reduction reaction (ORR), and hydrogen evolution reaction (HER). Platinum can efficiently drive these three types of reactions, but its scale-up application is limited by its susceptibility to poisoning and high cost. In order to reduce the cost and alleviate poisoning, incorporating Pt with various metals proves to be an efficient and feasible strategy. Herein, PtFeCoNiIr/C trifunctional high-entropy alloy (HEA) catalysts are prepared with uniform mixing and ultra-small size of 2 ± 0.5 nm by Joule heating method. PtFeCoNiIr/C exhibits efficient performance in AOR (J = 139.8 A g ), ORR (E = 0.87 V), and HER (E = 20.3 mV), outperforming the benchmark Pt/C, and no loss in HER performance at 100 mA cm for 200 h. The almost unchanged E in the anti-poisoning test indicates its promising application in real fuel cells powered by ammonia. This work opens up a new path for the development of multi-functional electrocatalysts and also makes a big leap toward the exploration of cost-effective device configurations for novel fuel cells.
PubMed: 38953333
DOI: 10.1002/smll.202400892 -
PeerJ 2024The aim of this study was threefold. Firstly, it aimed to introduce and detail a novel method for chemically etching the bases of stainless-steel orthodontic brackets.... (Randomized Controlled Trial)
Randomized Controlled Trial Comparative Study
Comparative bond failure rate of orthodontic brackets when bracket base is treated with micro-abrasive blasting . acid etching: eighteen month randomized control trial and scanning electron microscope study.
BACKGROUND
The aim of this study was threefold. Firstly, it aimed to introduce and detail a novel method for chemically etching the bases of stainless-steel orthodontic brackets. Secondly, the study sought to investigate the structural alterations within the brackets' microstructure following chemical etching compared to those with sandblasted bases, using electron microscopy analysis. Lastly, the study aimed to evaluate and compare the long-term durability and survivability of orthodontic brackets with chemically etched bases those with sandblasted bases, both bonded using the conventional acid etch technique with Transbond XT adhesive, over an 18-month follow-up period.
METHODS
The study was a randomized clinical control trial with triple blinding and split-mouth study design and consisted of two groups. The brackets in the sandblasted group were prepared by sandblasting the intaglio surface of the base of the bracket with 50 µm SiO particles. Hydrofluoric acid was used to roughen the base in the acid-etched group. The bases of the brackets were viewed under an electron microscope to analyze the topographical changes.
RESULTS
A total of 5,803 brackets (3,006 acid-etch, 2,797 sandblasted) in 310 patients were bonded, in a split-mouth design by the same operator. The patients were followed for 18 months. The failure rate of 2.59% and 2.7% was noted in an acid-etched and sandblasted group, respectively. There was a close approximation of curves in the Kaplan-Meier plot, and the survival distribution of the two groups in the log-rank (Mantel-Cox) test was insignificant; x2 = 0.062 ( value = 0.804).
CONCLUSION
Acid etching if the bases of the brackets can be used as an alternative to sandblasting furthermore acid etching can be performed on the chair side.
Topics: Orthodontic Brackets; Humans; Acid Etching, Dental; Microscopy, Electron, Scanning; Female; Male; Dental Bonding; Adolescent; Surface Properties; Adult; Resin Cements; Young Adult; Stainless Steel; Dental Etching
PubMed: 38952970
DOI: 10.7717/peerj.17645 -
RSC Advances Jun 2024The search for novel intrinsic two-dimensional (2D) magnetic materials is crucial to understand the fundamentals of 2D magnetism and realize next-generation...
The search for novel intrinsic two-dimensional (2D) magnetic materials is crucial to understand the fundamentals of 2D magnetism and realize next-generation magneto-electric and magneto-optical systems. Using the rigorous framework of spin-polarized density functional theory (SPDFT)-based calculations, this investigation systematically investigates the effects of a stepwise change in the Fe composition () on the structural, electro-magnetic and optical properties of the ordered SrS based single-layer alloys, with encompassing values from 0 to 1. Our comprehensive analysis revealed that the calculated formation energies, cohesive energies, phonon dispersions, molecular dynamics, and elastic constants of both bare SrS and FeS monolayers indicate their thermodynamic, dynamic, thermal, and mechanical stability in hexagonal and square structures, respectively. Significantly, the introduction of magnetic Fe dopants into the non-magnetic SrS semiconductor enabled the creation of an intrinsic magnetic (FM) state characterized by spin-polarized charge carriers at the Fermi level ( ). As doping increases, the electronic structure shows a noticeable dependence on the chemical composition. It is noteworthy that the systems doped with 0.750 and 1 Fe exhibit metallic-magnetic and metallic non-magnetic properties, respectively, and the rest are half-semiconductors (HSC) according to the GGA approximation. Conversely, the HSE approach shows a transition to HSC for a doping level of 0.750, while others maintain the same behavior. The study of the optical properties shows improvements compared to the bare SrS monolayer through the incorporation of Fe dopants. The bare SrS has light absorption in the ultraviolet region, while the absorption band edges for HSC compounds change from the infrared to visible regions. This study proposes a practical method to tune the properties of the SrS single-layer by selectively adjusting the dopant concentration. Such control is promising for applications in spintronics and optical based nanodevices.
PubMed: 38952946
DOI: 10.1039/d4ra04352a -
International Journal of Nanomedicine 2024Implants are widely used in the field of orthopedics and dental sciences. Titanium (TI) and its alloys have become the most widely used implant materials, but...
BACKGROUND
Implants are widely used in the field of orthopedics and dental sciences. Titanium (TI) and its alloys have become the most widely used implant materials, but implant-associated infection remains a common and serious complication after implant surgery. In addition, titanium exhibits biological inertness, which prevents implants and bone tissue from binding strongly and may cause implants to loosen and fall out. Therefore, preventing implant infection and improving their bone induction ability are important goals.
PURPOSE
To study the antibacterial activity and bone induction ability of titanium-copper alloy implants coated with nanosilver/poly (lactic-co-glycolic acid) (NSPTICU) and provide a new approach for inhibiting implant-associated infection and promoting bone integration.
METHODS
We first examined the in vitro osteogenic ability of NSPTICU implants by studying the proliferation and differentiation of MC3T3-E1 cells. Furthermore, the ability of NSPTICU implants to induce osteogenic activity in SD rats was studied by micro-computed tomography (micro-CT), hematoxylin-eosin (HE) staining, masson staining, immunohistochemistry and van gieson (VG) staining. The antibacterial activity of NSPTICU in vitro was studied with gram-positive and gram-negative bacteria. was used as the test bacterium, and the antibacterial ability of NSPTICU implanted in rats was studied by gross view specimen collection, bacterial colony counting, HE staining and Giemsa staining.
RESULTS
Alizarin red staining, alkaline phosphatase (ALP) staining, quantitative real-time polymerase chain reaction (qRT-PCR) and western blot analysis showed that NSPTICU promoted the osteogenic differentiation of MC3T3-E1 cells. The in vitro antimicrobial results showed that the NSPTICU implants exhibited better antibacterial properties. Animal experiments showed that NSPTICU can inhibit inflammation and promote the repair of bone defects.
CONCLUSION
NSPTICU has excellent antibacterial and bone induction ability, and has broad application prospects in the treatment of bone defects related to orthopedics and dental sciences.
Topics: Animals; Anti-Bacterial Agents; Osteogenesis; Polylactic Acid-Polyglycolic Acid Copolymer; Mice; Staphylococcus aureus; Coated Materials, Biocompatible; Rats, Sprague-Dawley; Escherichia coli; Cell Differentiation; Prostheses and Implants; Alloys; Rats; Titanium; Silver; Cell Proliferation; Copper; Male; X-Ray Microtomography; Cell Line; Metal Nanoparticles
PubMed: 38952675
DOI: 10.2147/IJN.S456906 -
Pakistan Journal of Medical Sciences Jul 2024Metallic copper alloys have gained attention recently as a cutting-edge antibacterial weapon for areas where surface hygiene is crucial. The present study aimed to...
OBJECTIVE
Metallic copper alloys have gained attention recently as a cutting-edge antibacterial weapon for areas where surface hygiene is crucial. The present study aimed to assess copper coupons (99% Cu) for their potential to decrease the viability of various strains from inanimate hospital surfaces.
METHODS
This in vitro-experimental study was conducted at the Microbiology Laboratory, Faculty of Natural and Life Sciences and Earth and Universe Sciences, University of Guelma, and Khodja Ahmed Public Hospital Establishment, Algeria, for a period of six months from January to May 2022. A total of 85 samples were collected from patient room door handles and bed rails at the government hospital in Guelma State, from which 12 enterobacterial isolates were obtained. These isolates were evaluated for susceptibility to copper and polyvinyl chloride (PVC) coupons using plate counts to determine bacterial viability after 72 hours of incubation at 37°C or room temperature (25°C). Antibiotic sensitivity testing was then carried out using a modified Kirby-Bauer disc diffusion method. Copper coupons' ability to either select for or create antibiotic resistance is also determined.
RESULTS
Copper showed a bactericidal effect after three hours for and six hours for . Whereas it was shown that within three days of selection, 83.33% of strains are capable of rapidly acquiring Cu resistance. Indeed, the increase in temperature reduced the effects of Cu (p<0.05; Student's t-test). Antimicrobial susceptibility testing revealed that the copper-resistant bacteria were less sensitive than their predecessors. strains showed the highest incidence of multidrug resistance. The most significant findings included widespread resistance to beta-lactams (100%-75%) and chloramphenicol (66.67%).
CONCLUSION
These results suggest that prolonged copper usage may contribute to the development of antibiotic resistance, which could have significant ramifications.
PubMed: 38952496
DOI: 10.12669/pjms.40.6.8435 -
Heliyon Jun 2024This review paper covers an analysis of the empirical calculations, additive manufacturing (AM) and hydrogen storage of refractory high-entropy alloys undertaken to... (Review)
Review
This review paper covers an analysis of the empirical calculations, additive manufacturing (AM) and hydrogen storage of refractory high-entropy alloys undertaken to determine the structural compositions, particularly focusing on their applicability in research and experimental settings. The inventors of multi-component high-entropy alloys (HEAs) calculated that trillions of materials could be manufactured from elements in the periodic table, estimating a vast number, N = 10^100, using Stirling's approximation. The significant contribution of semi-empirical parameters such as Gibbs free energy , enthalpy of mixing , entropy of mixing , atomic size difference , valence electron concentration , and electronegativity difference are to predict BCC and/or FCC phases in HEAs. Additive manufacturing facilitates the determination of refractory HEAs systems with the most stable solid-solution and single-phase, and their subsequent hydrogen storage capabilities. Hydride materials, especially those from HEAs manufactured by AM as bulk and solid materials, have great potential for H storage, with storage capacities that can be as high as 1.81 wt% of H adsorbed for a ZrTiVCrFeNi system. Furthermore, laser metal deposition (LMD) is the most commonly employed technique for fabricating refractory high entropy alloys, surpassing other methods in usage, thus making it particularly suitable for H storage.
PubMed: 38952385
DOI: 10.1016/j.heliyon.2024.e32715 -
Langmuir : the ACS Journal of Surfaces... Jul 2024The key to enhancing water electrolysis efficiency lies in selecting highly efficient catalysts. Currently, high-entropy alloys (HEAs) are utilized in electrocatalysis...
The key to enhancing water electrolysis efficiency lies in selecting highly efficient catalysts. Currently, high-entropy alloys (HEAs) are utilized in electrocatalysis applications owing to their diverse elemental composition, disordered elemental distribution, and the high solubility of each element, endowing them with excellent catalytic performance. The experiments were conducted using isoatomic FeNiCrMo HEA as a precursor, with a high-activity three-dimensional nanoporous structure rapidly synthesized via electrochemical one-step dealloying in a choline chloride-thiourea (ChCl-TU) deep eutectic solvent (DES). The results indicate that the dealloyed FeCoNiCrMo HEA mainly consists of two phases: face-centered cubic and σ phases. The imbalance in the distribution of elements in these two phases leads to quite different corrosion speeds with the FCC phase being preferentially corroded. Furthermore, synergistic electron coupling between surface atoms in the three-dimensional nanoporous structure strengthens the behavior of the oxygen evolution reaction (OER). At a current density of 40 mA cm, the overpotential after dealloying decreased to 370 mV, demonstrating excellent stability. The technique demonstrated in this work provides a novel approach to improve the catalytic activity of OER.
PubMed: 38950193
DOI: 10.1021/acs.langmuir.4c00769 -
Small (Weinheim An Der Bergstrasse,... Jul 2024Creating durable and efficient multifunctional electrocatalysts capable of high current densities at low applied potentials is crucial for widespread industrial use in...
Creating durable and efficient multifunctional electrocatalysts capable of high current densities at low applied potentials is crucial for widespread industrial use in hydrogen production. Herein, a Co-Ni-Fe-Cu-Mo (oxy)hydroxide electrocatalyst with abundant grain boundaries on nickel foam using a scalable coating method followed by chemical precipitation is synthesized. This technique efficiently organizes hierarchical Co-Ni-Fe-Cu-Mo (oxy)hydroxide nanoparticles within ultrafine crystalline regions (<4 nm), enriched with numerous grain boundaries, enhancing catalytic site density and facilitating charge and mass transfer. The resulting catalyst, structured into nanosheets enriched with grain boundaries, exhibits superior electrocatalytic activity. It achieves a reduced overpotential of 199 mV at 10 mA cm current density with a Tafel slope of 48.8 mV dec in a 1 m KOH solution, maintaining stability over 72 h. Advanced analytical techniques reveal that incorporating high-valency copper and molybdenum elements significantly enhances lattice oxygen activation, attributed to weakened metal-oxygen bonds facilitating the lattice oxygen mechanism (LOM). Synchrotron radiation studies confirm a synergistic interaction among constituent elements. Furthermore, the developed high-entropy electrode demonstrates exceptional long-term stability under high current density in alkaline environments, showcasing the effectiveness of high-entropy strategies in advancing electrocatalytic materials for energy-related applications.
PubMed: 38949312
DOI: 10.1002/smll.202401034 -
Imaging Science in Dentistry Jun 2024This study examined the influence of a metal artifact reduction (MAR) tool, sharpening filters, and their combination on the diagnosis of vertical root fracture (VRF) in...
PURPOSE
This study examined the influence of a metal artifact reduction (MAR) tool, sharpening filters, and their combination on the diagnosis of vertical root fracture (VRF) in teeth with metallic posts using cone-beam computed tomography (CBCT).
MATERIALS AND METHODS
Twenty single-rooted human premolars - 9 with VRF and 11 without - were individually placed in a human mandible. A metallic post composed of a cobalt-chromium alloy was inserted into the root canal of each tooth. CBCT scans were then acquired under the following parameters: 8 mA, a 5×5 cm field of view, a voxel size of 0.085 mm, 90 kVp, and with MAR either enabled or disabled. Five oral and maxillofacial radiologists independently evaluated the CBCT exams under each MAR mode and across 3 sharpening filter conditions: no filter, Sharpen 1×, and Sharpen 2×. The diagnostic performance was quantified by the area under the receiver operating characteristic curve (AUC), sensitivity, and specificity. These metrics were compared using 2-way analysis of variance with a significance level of α=5%. Intra- and inter-examiner agreement were assessed using the weighted kappa test.
RESULTS
Neither MAR nor the application of sharpening filters significantly impacted AUC or specificity (>0.05). However, sensitivity increased when MAR was combined with Sharpen 1× and Sharpen 2× (=0.015). The intra-examiner agreement ranged from fair to substantial (0.34-0.66), while the inter-examiner agreement ranged from fair to moderate (0.27-0.41).
CONCLUSION
MAR in conjunction with sharpening filters improved VRF detection; therefore, their combined use is recommended in cases of suspected VRF.
PubMed: 38948185
DOI: 10.5624/isd.20230233