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Objective: The objective of this study was to evaluate the impact of daily mouthwash rinsing protocols recommended against SARS-CoV-2 on metal ions discharged from fixed orthodontic appliances, specifically Nickel (Ni) and Chromium (Cr). Material and Methods: Total of 400 hemi-arch fixed appliances were segregated into two groups, namely Nickel Titanium (NiTi) and Stainless Steel (SS), based on the type of archwire employed. Each set was submerged in 2% povidone-iodine, 1% hydrogen peroxide, 0.2% chlorhexidine and cetylpyridinium chloride mouthwashes. Distilled water was used for comparative measurements of the ions released as a control group (n=10/group). They were incubated for four periods at 37°C (one hour, twenty-four hours, one, and 3 weeks). Nil and Cr ions released from the fixed appliance were evaluated by atomic absorption spectroscopy. The data were analyzed by the Kruskal-Wallis test and paired comparison analysis. Results: The worst levels of Ni and Cr liberated from the SS group observed in povidone-iodine mouthwash at 1.173 and 1.701 ppm, respectively, while the chlorhexidine mouthwash released accepted level of Ni and Cr at 0.033 and 0.056 ppm, respectively. The NiTi group displayed the appalling ions released of Ni and Cr in povidone-iodine mouthwash at 1.87 and 2.4 ppm, respectively. Whereas the released levels of Ni and Cr ions from the chlorhexidine group and cetylpyridinium chloride were 0.048 and 0.127 ppm, respectively, with significant differences between the tested groups and intervals. Conclusion: Chlorhexidine and Cetylpyridinium chloride mouthwashes were the appropriate options for orthodontic patients to minimized ions released according to this study protocol.(AU)

Objetivo: O objetivo deste estudo é avaliar o impacto dos protocolos diários de enxaguatório bucal recomendados contra SARS-CoV-2 em íons metálicos liberados de aparelhos ortodônticos fixos, especificamente Níquel (Ni) e Cromo (Cr). Material e Métodos: Um total de 400 aparelhos fixos de hemiarcada foram segregados em dois grupos, Níquel Titânio (NiTi) e Aço Inoxidável (SS), com base no tipo de fio utilizado. Cada conjunto foi submerso em enxaguantes bucais com iodopovidona a 2%, peróxido de hidrogênio a 1%, clorexidina a 0,2% e cloreto de cetilpiridínio. Água destilada foi utilizada para medições comparativas dos íons liberados como grupo controle (n=10/grupo). Eles foram incubados por cinco períodos a 37°C (uma hora, vinte e quatro horas, uma e 3 semanas). Os íons Nil e Cr liberados do aparelho fixo foram avaliados por espectroscopia de absorção atômica. Os dados foram analisados pelo teste de Kruskal-Wallis e análise de comparação pareada. Resultados:Os piores níveis de Ni e Cr liberados no grupo SS foram observados no enxaguatório bucal com iodopovidona em 1,173 e 1,701 ppm, respectivamente, enquanto o enxaguatório bucal com clorexidina liberou níveis aceitos de Ni e Cr em 0,033 e 0,056 ppm, respectivamente. O grupo NiTi exibiu os terríveis íons liberados de Ni e Cr no enxaguatório bucal com iodopovidona a 1,87 e 2,4 ppm, respectivamente. Já os níveis liberados de íons Ni e Cr do grupo clorexidina e cloreto de cetilpiridínio foram 0,048 e 0,127 ppm, respectivamente, com diferenças significativas entre os grupos e intervalos testados. Conclusão: Enxaguatórios bucais com clorexidina e cloreto de cetilpiridínio foram as opções adequadas para pacientes ortodônticos para minimizar a liberação de íons de acordo com o protocolo deste estudo(AU)

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Introduction: The release of metallic ions from orthodontic brackets and wires typically depends on their quality (chemical composition) and the medium to which they are exposed, e.g., acidic, alkaline, substances with a high fluoride concentration, etc. This review examines corrosion and wear of orthodontic brackets, wires, and arches exposed to different media, including: beverages (juices), mouthwashes and artificial saliva among others, and the possible health effects resulting from the release of metallic ions under various conditions. Objective: This review aims to determine the exposure conditions that cause the most wear on orthodontic devices, as well as the possible health effects that can be caused by the release of metallic ions under various conditions. Sources: A search was carried out in the Scopus database, for articles related to oral media that can corrode brackets and wires. The initial research resulted in 8,127 documents, after applying inclusion and exclusion criteria, 76 articles remained. Conclusion: Stainless steel, which is commonly used in orthodontic devices, is the material that suffers the most wear. It was also found that acidic pH, alcohols, fluorides, and chlorides worsen orthodontic material corrosion. Further, nickel released from brackets and wires can cause allergic reactions and gingival overgrowth into patients.

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Mangrove forests have been reported as sinks for metals because of the immobilization of these elements in their soils. However, climate change may alter the functioning of these ecosystems. We aimed to assess the geochemical dynamics of Mn, Cu, and Zn in the soils of a mangrove forest dead by an extreme weather event in southeastern Brazil. Soil samples were collected from dead and live mangroves adjacent to each other. The physicochemical parameters (total organic carbon, redox potential, and pH), total metal content, particle size, and metal partitioning were determined. Distinct changes in the soil geochemical environment (establishment of suboxic conditions) and a considerable loss of fine particles was caused by the death of the mangroves. Our results also showed a loss of up to 93 % of metals from soil. This study highlights the paradoxical role of mangroves as potential metal sources in the face of climate change.

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The sulphide-rich mine wastes accumulated in tailing dumps of La Concordia Mine (Puna of Argentina) have been exposed to the weathering action for more than 30 years. Since then, a series of redox reactions have triggered the generation of a highly acidic drainage -rich in dissolved metals-that drains into the La Concordia creek. The extent of metal and acid release in the site was analysed through field surveys and laboratory experiments. Static tests were conducted in order to predict the potential of the sulphidic wastes to produce acid, while Cu-, Zn-, Fe- and Pb-bearing phases present in the wastes were identified by XRD, SEM/EDS analysis and sequential extraction procedures. Finally, the release of these metals during sediment-water interaction was assessed in batch experiments carried out in a period of nearly two years. Field surveys indicate that the prolonged alteration of the mine wastes led to elevated electrical conductivity, pH values lower than 4 and metal concentrations that exceed the guide values for drinking water in the La Concordia stream regardless of the dominating hydrological conditions. The highly soluble Fe and Mg (hydrous)sulphates that form salt crusts on the tailings surfaces and the riverbed sediments play an important role in the control of metal mobility, as they rapidly dissolve in contact with water releasing Fe, but also Cu and Zn which are scavenged by such minerals. Another important proportion of the analysed metals is adsorbed onto Fe (hydr)oxides or form less soluble hydroxysulfates. Metals present in these phases are released to water more slowly, thus representing a potential long term source of heavy metal pollution. The obtained results are a contribution to the understanding of long term metal transformations and mobility in mine waste-impacted sites.

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This manuscript evaluates the potential application of active nanocomposite films based on soy protein isolate (SPI)-montmorillonite (MMT)-clove essential oil (CEO) to the preservation of muscle fillets of bluefin tuna (Thunnus thynnus) during refrigerated storage, and furthermore analyzes whether the clay diffuses from the package to food. SPI films with: CEO (SPI-CEO), MMT (SPI-MMT), or both CEO and MMT (SPI-MMT-CEO), were prepared and used to cover tuna fillets during 17days of storage at 2°C. Polyethylene films were also used as control. Protein films nanoreinforced with 10g MMT/100g SPI and activated with CEO were able to decrease microbial growth (evaluated by TVBN and microorganism counts) and lipid autooxidation (evaluated according to the TBA index, FTIR and color parameters) of tuna fillets during the storage period studied. The presence of clay seemed to favor the release of the active principles of clove oil by prolonging its antimicrobial (especially effective to inhibit Pseudomonas spp.) and antioxidant activity over time without observing the diffusion of the clay's own metals (Si and Al) from the nanocomposite materials to the muscle of fish. These results are encouraging for the use of nanocomposite films in food packaging.

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