cobalt chromium
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2022 ◽  
Author(s):  
Wenjin Li ◽  
Jing Shi ◽  
Wenjin Bian ◽  
Jianting Li ◽  
Xiaoqing Chen ◽  
...  

Abstract This study aimed to compare MRI quality between common fast spin echo T2 weighted imaging (FSE T2WI) with periodically rotated overlapping parallel lines with enhanced reconstruction (PROPELLER) FSE T2WI for patients with various porcelain fused to metal (PFM) crown and analyze the value of PROPELLER technique in reducing metal artifacts. Common FSE T2WI and PROPELLER FSE T2WI sequences for axial imaging of head were applied in participants with different PFM crowns: cobalt-chromium (Co-Cr) alloy, pure titanium (Ti), gold-palladium (Au-Pd) alloy. Two radiologists evaluated overall image quality of section in PFM using a 5-point scale qualitatively and measured the maximum artifact area and artifact signal-to-noise ratio (SNR) quantitatively. The metal crown with the least artifacts and the optimum image quality shown in common FSE T2WI and PROPELLER FSE T2WI were in Au–Pd alloy, Ti, and Co–Cr alloy order. PROPELLER FSE T2WI was superior to common FSE T2WI in improving image quality and reducing artifact area for Co-Cr alloy (17.0±0.2% smaller artifact area, p<0.001) and Ti (11.6± 0.7 % smaller artifact area, p=0.005), but had similar performance compared to FSE T2WI for Au-Pd alloy. For all PFMs, PROPELLER FSE T2WI significantly reduced the signal-to-noise ratio (SNR) of artifact (393.57±89.75 VS. 214.05±70.45, p < 0.001) when compared to common FSE T2WI.Therefore, the different PFM crown generate varying degrees of metal artifacts in MRI, and the PROPELLER can effectively reduce metal artifacts especially in the PFM crown of Co-Cr alloy.


2022 ◽  
Vol 10 (D) ◽  
pp. 1-5
Author(s):  
Mohammed Muwafi ◽  
Marwa Sabet ◽  
Yasmine Thabet

BACKGROUND: Numerous attempts were made to reduce the adverse effects of the distal extension removable partial dentures (RPDs) and enhance their prognosis. High-performance polymers (HPP) were utilized in the construction of RPDs to maintain the health of the supporting structures. AIM: Thus, this study was prompted to compare the strains induced by Bio HPP and Cobalt- Chromium (Co Cr) Computer Assisted Design and Computer Assisted Manufacturing telescopic RPDs after 1 year of function. MATERIALS AND METHODS: A maxillary Kennedy class I was used in this study. Twelve telescopic RPDs were fabricated from two different materials. In Group A, six telescopic RPDs were milled from Co-Cr and in Group B, six telescopic retained RPDs were milled from Bio-HPP. Each partial denture was seated on the cast and introduced into the chewing simulator. The strain values were recorded using four strain gauges connected to a four-channel strain indicator. Statistical analysis of the resultant data was done using one-way ANOVA, followed by Tukey’s HSD for comparison within the same group. Student t-test was used for comparison between the different groups. The significance level was set at p ≤ 0.05. RESULTS: During unilateral loading, the results showed higher strains in Group A at the abutments (473.33 μm/m ± 10.8, 193.39 μm/m ± 10.8) and at the distal aspect of the ridge (470.83 μm/m ± 13.93, 185 μm/m ± 20.83) than Group B. Independent t-test showed statistically significant difference between strains at the abutments of both groups (t = 70.4, p ≤ 0.0001), (t = 36.84, p ≤ 0.0001). Furthermore, there was a statistically significant difference between strains at the saddles of both groups (t = 51.62, p ≤ 0.0001), (t = 34.72, p ≤ 0.0001) respectively (DOF = 10). CONCLUSIONS: In telescopic RPDs, Co Cr induces higher strain values on the abutments and the distal aspect of the ridge than Bio-HPP during bilateral and unilateral loading. During unilateral loading, Bio-HPP telescopic RPDs direct high strain values on the distal aspect of the ridge of the loaded side. CLINICAL IMPLICATIONS: The materials that induce less stresses on the supporting structures of telescopic partial dentures on the long-term can be used to maintain the health of periodontally affected abutments.


2022 ◽  
Author(s):  
Sakila Khatun ◽  
Poulomi Roy

Cobalt chromium vanadium layered triple hydroxide has been identified as a promising electrocatalyst for seawater splitting. The insertion of vanadium as third metal into cobalt chromium layered double hydroxide not...


2021 ◽  
Vol 12 (4) ◽  
Author(s):  
Maria Kassapidou ◽  
Victoria Franke Stenport ◽  
Carina B. Johansson ◽  
Anna-Karin Östberg ◽  
Petra Hammarström Johansson ◽  
...  

Author(s):  
Pedro Conceição ◽  
◽  
Margarida Franco ◽  
Nuno Alves ◽  
Jaime Portugal ◽  
...  

Objectives: To assess the effect of a CAD-CAM protocol fabrication on the clinical fit accuracy of removable partial denture metal frameworks to abutment teeth. Methods: Fifteen patients with partial edentulism were selected to participate in this clinical study, and twenty dental arch rehabilitations were planned. For each dental arch (n=20), two cobalt-chromium frameworks were produced through two protocols: CAD-CAM production (experimental group); and conventional lost-wax casting technique (control group). Clinical fit accuracy was assessed using an indirect quantitative method to evaluate the gap between the framework occlusal rest and the corresponding rest seat. A silicone mold of that gap was obtained, digitized, and analyzed by micro-computed tomography. The two silicone molds obtained for each occlusal rest were overlapped and evaluated for thickness and volume. Data were analyzed with the paired t test for silicone thickness results and the Wilcoxon test for silicone volume results (α= 0.05). Results: Considering the two dependent variables under study, no statistically significant (p=0.441 for silicone thickness and p=0.204 for silicone volume) differences were found between groups. Conclusions: The results of this study suggest that the CAD-CAM protocol applied is a viable method for the production of removable partial denture metal frameworks. (Rev Port Estomatol Med Dent Cir Maxilofac. 2021;62


2021 ◽  
Vol 10 (17) ◽  
pp. e162101724429
Author(s):  
Lucas José de Azevedo-Silva ◽  
Brunna Mota Ferrairo ◽  
Renato José Berro-Filho ◽  
Fernanda Ferruzzi Lima ◽  
José Henrique Rubo

Marginal and internal adaptation are parameters of crucial importance to the success of prosthetic crowns. Automatized process creates an expectative of superior or equivalent results compared to restorations manufactured ​​by conventional lost-wax technique. The purpose of this study was to evaluate the marginal adaptation and internal adaptation (cement space) of metal-ceramic crown copings produced by lost-wax (LW) and direct metal laser sintering (DMLS) techniques. An artificial lower first molar was prepared for a full crown, duplicated in plaster and scanned. Twenty metal-ceramic crown copings were fabricated in cobalt-chromium by the two techniques (n=10). The copings were filled with low viscosity silicone and seated on the prepared tooth, resulting in a replica of the internal space. The pellicle formed was embedded in heavy body silicone, sectioned and captured by means of a stereomicroscope at 50x magnification, according to replica technique (RT). Shapiro-Wilk test followed by Holm-Sidak test were used for statistical analysis (α=.05). Marginal adaptation presented no difference between LW (101.5 ± 41.6) and DMLS (86.3 ± 39.9) groups (p=0.24). Conventional LW technique showed significantly lower occlusal (p<0.008) and axial spaces (p<0.03).  Measurements of all regions showed numerically larger adaptation values than that defined during design​​ for DMLS group. Both the LW technique and the DMLS technique are within the clinically acceptable.


Author(s):  
Nina A. Dyakova ◽  

The Voronezh region is traditionally the most important area of crop production and agriculture. The purpose of the research was to study the contamination with heavy metals of medicinal plant raw materials of the Voronezh region using the example of the roots of ordinary burdock, prepared in urbo- and agro-ecosystems, which have various anthropogenic effects on themselves. The accumulation of heavy metals (lead, mercury, cadmium, nickel, copper, zinc, cobalt, chromium) and arsenic in 51 samples of raw materials was studied. By comparing the heavy metal content in the upper soil layers of the region and the content of these elements in the roots of the bladder, it can be assumed that there are significant physiological barriers to the accumulation of ecotoxicants in the roots of the bladder, which is especially noticeable for elements such as lead, mercury, arsenic, cadmium, cobalt and chromium. At the same time, this type of medicinal vegetal raw material is able to selectively concentrate some heavy metals included in the active centers of enzyme systems (copper and zinc). Thus, for an ordinary bladder under conditions of anthropogenic load, an edaphotype is formed, which is as a result of selection in conditions of anthropogenic pollution of the external environment and the manifestation of adaptation to these conditions.


Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7554
Author(s):  
Muhammad Imam Ammarullah ◽  
Ilham Yustar Afif ◽  
Mohamad Izzur Maula ◽  
Tri Indah Winarni ◽  
Mohammad Tauviqirrahman ◽  
...  

The selection of biomaterials for bearing in total hip arthroplasty is very important to avoid various risks of primary postoperative failure for patients. The current investigation attempts to analyze the Tresca stress of metal-on-metal bearings with three different materials, namely, cobalt chromium molybdenum (CoCrMo), stainless steel 316L (SS 316L), and titanium alloy (Ti6Al4V). We used computational simulations using a 2D axisymmetric finite element model to predict Tresca stresses under physiological conditions of the human hip joint during normal walking. The simulation results show that Ti6Al4V-on-Ti6Al4V has the best performance to reduce Tresca stress by 45.76% and 39.15%, respectively, compared to CoCrMo-on-CoCrMo and SS 316L-on-SS 316L.


2021 ◽  
Vol 2 (2) ◽  
pp. 49
Author(s):  
Rezza Ruzuqi ◽  
Drs. Djony Izak Rudyardjo, M.Si. ◽  
Andi Hamim Zaidan, S.Si., M.Si., Ph.D.

The research has been conducted to manufacture nickel-based Superalloy materials. The purpose of this research was to find out the effects of variation of nickel composition on physical and mechanical properties of the Superalloy materials and find out the appropriate composition of Superalloy materials as materials for turbine blades. This research used nickel, cobalt, chromium, molybdenum, aluminium, and titanium commercial. The results showed that with more addition of nickel composition, the density and hardness values increased. This research showed that nickel-based Superalloy material 59 wt% was better applied as materials for turbine blades. It is also supported by the results of the test microstructure, where the structure of the sample morphology is more delicate and denser and contains smaller pores. Based on the XRD test results are also shown in the sample has been formed Superalloys phase.


Alloy Digest ◽  
2021 ◽  
Vol 70 (12) ◽  

Abstract Ugitech UGI HT605 (UNS R30605) is a solid solution strengthened, wrought cobalt-chromium-tungsten-nickel alloy with excellent high-temperature strength and excellent oxidation resistance up to 1095 °C (2000 °F). This datasheet provides information on composition, physical properties, and tensile properties. It also includes information on corrosion resistance as well as casting, heat treating, machining, and joining. Filing Code: Co-143. Producer or source: Ugitech SA (member of Swiss Steel Group).


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