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1.
J Esthet Restor Dent ; 32(5): 530-535, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32180345

RESUMO

OBJECTIVE: The aim of this study was to investigate the color change, translucency, and whiteness index of three different resin matrix ceramics and a resin composite subjected to different bleaching agents. MATERIALS AND METHODS: Twenty disc-shaped specimens (A2 shaded) for three different resin matrix ceramic brands (Groups Ena, Ulti, and Cera) (totally 60) were prepared using the CAD/CAM technique and 20 nanofiller composite specimens (Group Comp) (A2 shaded) with the same dimensions were prepared as the control group. The color change (∆E00 ), relative translucency parameter (RTP), and whiteness index (WID ) of the specimens initial and after different bleaching procedures (home-bleaching and office-bleaching) were calculated using ∆E00 , TP00 , and WID formulas. Two-way analysis of variance (ANOVA) and multiple comparison test with Bonferroni correction (α = .05) at the significance level of P < .05 were performed for the comparisons of ∆E00 values. The RTP and WID values were evaluated by using repeated measures ANOVA and multiple-comparison test with Bonferroni corrections (α = .05) at the significance level of P < .05. RESULTS: Bleaching procedure and material type were found to be significant regardless of bleaching type for RTP and WID values. Material type has a significant effect on the ∆E00 values. The highest color change values were determined in Group Comp (P < .05). CONCLUSIONS: Bleaching procedures significantly affected the RTP values of Groups Ulti and Cera (P < .05). ∆E00 values for the resin matrix ceramics after the bleaching procedures were below the clinically acceptable values, regardless of the bleaching agent. CLINICAL SIGNIFICANCE: Optically, materials such as resin matrix ceramics have properties different from not only enamel and dentin but also among themselves. The possible effect of bleaching agents on these materials should be considered carefully while choosing the restorative material.


Assuntos
Clareadores , Cerâmica , Cor , Resinas Compostas , Porcelana Dentária , Teste de Materiais , Propriedades de Superfície
2.
Biochim Biophys Acta Proteins Proteom ; 1868(2): 140312, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-31740412

RESUMO

Global economic growth often leads to depletion of raw materials and generation of greenhouse gases, as industry manufactures goods at ever increasing levels to keep up with the demand. The currently implemented production processes mostly rely on non-renewable resources, they suffer from high energy consumption, and generate waste that often has a negative environmental impact. Eco-friendly production methods are therefore intensely searched for. Among them, enzyme-based processes are appealing, because of their high substrate and reaction specificity and the relatively mild operation conditions required by these catalysts. In addition, renewable raw materials that allow sustainable production processes are also widely explored. Marine xylanases, which catalyze the hydrolysis of xylan, the major component of lignocellulose, are promising biocatalysts. Since they are produced by microorganisms that thrive in a wide variety of environmental conditions, the enzymes may be active at widely different ranges of pH, temperature, and salt concentrations. These properties are important for their successful application in various industrial processes, such as production of bioethanol, bleaching of paper and pulp, and in the food and feed sector. The present work gives a brief overview of marine sources of xylanases, their classification and features, and of the potential applications of these marine enzymes, especially in sustainable processes in the scope of circular economy.


Assuntos
Endo-1,4-beta-Xilanases/metabolismo , Clareadores/química , Clareadores/metabolismo , Endo-1,4-beta-Xilanases/classificação , Concentração de Íons de Hidrogênio , Cinética , Lignina/metabolismo , Probióticos , Energia Renovável , Alga Marinha/enzimologia
3.
J Appl Microbiol ; 128(1): 161-170, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31609034

RESUMO

AIMS: The utilization of micro-organisms in pulp and paper industries has proved biobleaching technology as an environmentally friendly alternative to the conventional approach. In this paper, the effect of actinobacterial fermentation broth on pulp biobleaching has been investigated. METHODS AND RESULTS: Actinobacterial colonies were isolated from lignocellulose-rich soil samples and screened for xylanase production and bleaching activity. The most efficient isolate in bleaching activity showed 100% similarity to Streptomyces rutgersensis. Pulp treatment with 5-day fermentation broth of this strain showed up to 7% increase in brightness (30°C for 6 h, pH (5-7)) compared to untreated (control) pulp. Also, after 60 min biotreatment, significant reduction (12·5%) in consumption of bleaching chemicals was achieved to obtain final brightness of 55%. CONCLUSION: Actinobacterial fermentation broth can be considered as a rich source of effective biobleaching agents which may be considered as environmental friendly and cost-effective technique in comparison with traditional method. SIGNIFICANCE AND IMPACT OF THE STUDY: Our findings showed ability of S. rutgersensis UTMC 2445 in bleaching chemomechanical paper pulp. Also, two strains of Saccharothrix, a rare actinobacterium, with biobleaching activity were introduced. In the proposed method, there is no need to use purified enzymes, and biobleaching process can be done using the fermentation broth.


Assuntos
Clareadores/metabolismo , Lignina/análise , Papel , Solo/química , Streptomyces/metabolismo , Actinomycetales/metabolismo , Endo-1,4-beta-Xilanases/metabolismo , Fermentação , Concentração de Íons de Hidrogênio , Lignina/metabolismo , Microbiologia do Solo , Streptomyces/enzimologia , Temperatura
4.
Braz. dent. sci ; 23(2): 1-8, 2020. tab, ilus
Artigo em Inglês | LILACS, BBO - Odontologia | ID: biblio-1096444

RESUMO

Objective: This study's aim was to quantify the hydrogen peroxide (HP) penetration into the pulp chamber of teeth submitted to different protocols of bleaching. Material and Methods: Ninety premolars were randomly divided into nine groups according to the bleaching agent protocol (n = 10): control (no bleaching), carbamide peroxide 10% [10% CP], carbamide peroxide 16% [16% CP], carbamide peroxide 22% [22% CP], hydrogen peroxide 4% [4% HP], hydrogen peroxide 6% [6% HP], hydrogen peroxide 7.5% [7.5% HP], hydrogen peroxide 10% [10% HP] and hydrogen peroxide 35% [35% HP]. The penetration of HP was measured via spectrophotometric analysis of the acetate buffer solution from the pulp chamber. The absorbance of the resulting solution was determined in a spectrophotometer and converted into equivalent concentration of HP (µg/ mL). To analyze the concentration of HP, the titration of bleaching agents with potassium permanganate was used. Data were subjected to ANOVA and Tukey's test for pairwise comparison (α = 0.05). Results: Higher concentration of HP in the pulp chamber was found in the HP 35% group (p < 0.0001). No significant difference between at-home protocols were observed (p = 0.64). Titration values showed that the concentration of the products was similar to that claimed by the manufacturer. Conclusion: It follows that the amount of HP that reaches the pulp chamber is not proportional to the concentration of whitening gels, but depends on the application time recommended by the manufacturers (AU)


Objetivo: o objetivo deste estudo foi quantificar a penetração do peróxido de hidrogênio (PH) na câmara pulpar dos dentes submetidos a diferentes protocolos de clareamento. Material e Métodos: Noventa pré-molares foram divididos aleatoriamente em nove grupos, de acordo com o protocolo do agente clareador (n = 10): controle (sem clareamento), peróxido de carbamida 10% [PC 10%], peróxido de carbamida 16% [PC 16%], peróxido de carbamida 22% [PC 22%], peróxido de hidrogênio 4% [PH 4%], peróxido de hidrogênio 6% [PH 6%], peróxido de hidrogênio 7,5% [PH 7,5%], peróxido de hidrogênio 10% [PH 10%] e peróxido de hidrogênio 35% [PH 35%]. A penetração de PH foi medida por análise espectrofotométrica da solução de tampão de acetato da câmara pulpar. A absorvância da solução resultante foi determinada em um espectrofotômetro e convertida em concentração equivalente de PH (µg / mL). Para analisar a concentração de PH, foi utilizada a titulação de agentes clareadores com permanganato de potássio. Os dados foram submetidos à ANOVA e teste de Tukey para comparação pareada (α = 0,05). Resultados: Foi encontrada maior concentração de PH na câmara pulpar no grupo PH 35% (p < 0,0001). Não foi observada diferença significativa entre os protocolos domiciliares (p = 0,64). Os valores de titulação mostraram que a concentração dos produtos era semelhante à reivindicada pelo fabricante. Conclusão: Conclui-se que a quantidade de PH que atinge a câmara pulpar não é proporcional à concentração de géis clareadores, porém depende do tempo de aplicação recomendado pelos fabricantes.(AU)


Assuntos
Clareamento Dental , Permeabilidade do Esmalte Dentário , Clareadores , Peróxido de Carbamida , Peróxido de Hidrogênio
5.
Carbohydr Polym ; 225: 115211, 2019 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-31521267

RESUMO

Fucoidan from Laminaria japonica is a kind of sulfate polysaccharide with high molecular weight (MW) and broad bioactivities. This study was performed to investigate the relationship between MW and whitening activity of fucoidan and to exploit a novel functional ingredient for whitening cosmetics. High sulfate content fucoidan was enzymic degraded by Flavobacterium RC2-3 produced fucoidanase. Two hours were enough for the enzyme degradation to achieve degraded fucoidan with favorable tyrosinase inhibitory ability. The whitening activity of different MW fucoidan fractions were evaluated by their tyrosinase inhibitory ability, antioxidant activity and cellular melanogenesis inhibitory ability. Results showed that in the MW range above 5 kDa, the smaller MW of fucoidan were related to the better whitening activity. The fucoidan fraction with the MW between 5-10 kDa, presented the best tyrosinase inhibitory activity (62.0%), antioxidant activity (48.3%) and excellent anti-melanogenesis ability in B16 cells, which could be applied as the whitening factor in cosmetics development.


Assuntos
Clareadores , Laminaria/metabolismo , Polissacarídeos , Preparações Clareadoras de Pele , Animais , Antioxidantes , Clareadores/química , Clareadores/farmacologia , Linhagem Celular Tumoral , Peso Molecular , Monofenol Mono-Oxigenase/antagonistas & inibidores , Polissacarídeos/química , Polissacarídeos/farmacologia , Preparações Clareadoras de Pele/química , Preparações Clareadoras de Pele/farmacologia , Sulfatos/metabolismo
6.
PLoS Biol ; 17(8): e3000395, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-31465435

RESUMO

The gastric pathogen Helicobacter pylori requires a noncanonical cytosolic chemoreceptor transducer-like protein D (TlpD) for efficient colonization of the mammalian stomach. Here, we reconstituted a complete chemotransduction signaling complex in vitro with TlpD and the chemotaxis (Che) proteins CheW and CheA, enabling quantitative assays for potential chemotaxis ligands. We found that TlpD is selectively sensitive at micromolar concentrations to bleach (hypochlorous acid, HOCl), a potent antimicrobial produced by neutrophil myeloperoxidase during inflammation. HOCl acts as a chemoattractant by reversibly oxidizing a conserved cysteine within a 3His/1Cys Zn-binding motif in TlpD that inactivates the chemotransduction signaling complex. We found that H. pylori is resistant to killing by millimolar concentrations of HOCl and responds to HOCl in the micromolar range by increasing its smooth-swimming behavior, leading to chemoattraction to HOCl sources. We show related protein domains from Salmonella enterica and Escherichia coli possess similar reactivity toward HOCl. We propose that this family of proteins enables host-associated bacteria to sense sites of tissue inflammation, a strategy that H. pylori uses to aid in colonizing and persisting in inflamed gastric tissue.


Assuntos
Quimiotaxia/fisiologia , Helicobacter pylori/metabolismo , Receptores de Formil Peptídeo/metabolismo , Proteínas de Bactérias/metabolismo , Clareadores , Células Quimiorreceptoras/metabolismo , Fatores Quimiotáticos/metabolismo , Citosol/metabolismo , Citosol/fisiologia , Helicobacter pylori/fisiologia , Ácido Hipocloroso , Oxirredução , Receptores de Formil Peptídeo/fisiologia , Transdução de Sinais
7.
Braz Dent J ; 30(4): 385-396, 2019 Jul 22.
Artigo em Inglês | MEDLINE | ID: mdl-31340230

RESUMO

This study evaluated the decomposition rate (DR), pH, enamel color alteration (DE) and whiteness index (DWI) promoted by at-home and in-office bleaching. Enamel surface was submitted to (n=10): at-home (10%, 15%, 20% carbamide peroxide - CP, 6% hydrogen peroxide -HP) and three 35% HP agents with light irradiation (LED, laser, and halogen) or no treatment (control). The DR and pH of agents were measured after 0, 2, 4, 6 and 8 h (at-home) or after 5, 15, 20, 30 and 40 min (in-office). Color parameters (L*, a*, b*, DE, DWI) were determined at baseline and after bleaching. DR, pH, L*, a*, b* data were analyzed by one-way (at-home) or two-way (in-office) repeated measures ANOVA and Tukey test. DE and DWI, by one-way (at-home) or two-way (in-office) ANOVA and Tukey test. DR of at-home agents was similar after 6 and 8 h (p>0.05), with pH close to neutral (6.5 to 6.9, CP) or acid 5.9 (6% HP). From 4 to 8 h, DE was higher for 15% and 20% CP compared with 10% CP (p<0.05). After 40 min, DR of 35% HP agents was similar and all exhibited significant DE in one application (p<0.05), regardless light irradiation. DWI indicated whitening effect with no differences among groups (p>0.05). One 35% HP showed alkaline pH, and the others, pH < 5.5. At-home agents could be applied for 2 h (15%, 20% CP, 6% HP) and 4 h (10% CP) and the in-office agents, up to 40 min in one application, without light.


Assuntos
Clareadores , Clareadores Dentários , Clareamento Dental , Cor , Esmalte Dentário , Peróxido de Hidrogênio , Concentração de Íons de Hidrogênio , Peróxidos , Ureia
8.
Microsc Res Tech ; 82(10): 1720-1727, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31290589

RESUMO

This study evaluated the effects of an antioxidant application on the compromised bond strength of an adhesive to dentin bleached with 35% hydrogen peroxide. The dentin surfaces of the pulp chambers of 70 human third molars were ground, and the specimens were assigned randomly into seven groups, as follows: (a) control (unbleached); (b) bleached for 45 min, bonded immediately; (c) bleached for 45 min, treated with sodium ascorbate (SA) for 2 min, and bonded; (d) bleached for 45 min, bonded after 2 weeks; (e) bleached for 12 days, bonded immediately; (f) bleached for 12 days, treated with SA for 10 min, and bonded; and (g) bleached for 12 days, bonded after 2 weeks. In each group, the multimode adhesive was applied in etch-and-rinse and self-etch modes. The dentin surfaces were covered with a resin-based composite, and the bonded specimens were sectioned to produce composite-dentin sticks. The sticks were attached to a testing machine and subjected to a tensile force, and the representative specimens were examined via scanning electron microscopy. The bond strength was not affected by the application period of the bleaching agent. Both bleaching treatments significantly reduced the bond strength to the dentin in the self-etch or etch-and-rinse mode when compared with the control group. The bond strengths returned to normal levels with the SA applications or by waiting 2 weeks, regardless of the application period of the bleaching gel. The adhesive revealed a higher bond strength in the etch-and-rinse mode than in the self-etch mode.


Assuntos
Antioxidantes/metabolismo , Clareadores/metabolismo , Colagem Dentária , Cimentos Dentários/química , Dentina/efeitos dos fármacos , Humanos , Dente Molar/efeitos dos fármacos , Fatores de Tempo
9.
Scanning ; 2019: 2307305, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31281561

RESUMO

Objective: The aim of this study is to evaluate the microhardness and surface roughness of two different bulk-fill composites polymerized with light-curing unit (LCU) with different polymerization times before and after the application of a home bleaching agent. Materials-Methods: For both microhardness and surface roughness tests, 6 groups were prepared with bulk-fill materials (SonicFill, Filtek Bulk Fill) according to different polymerization times (10, 20, and 30 s). 102 specimens were prepared using Teflon molds (4 mm depth and 5 mm diameter) and polymerized with LCU. 30 specimens (n = 5) were assessed for microhardness. Before home bleaching agent application, the bottom/top (B/T) microhardness ratio was evaluated. After bleaching agent application, the microhardness measurements were performed on top surfaces. Roughness measurements were performed in 72 specimens (n = 12) before and after bleaching application. Additionally, for SEM analyses, two specimens from all tested groups were prepared before and after bleaching agent application. The data B/T microhardness ratio before bleaching was analyzed by two-way ANOVA and Tukey's HSD test. The data from the top surface of specimens' microhardness before and after bleaching were analyzed using Wilcoxon signed-rank test, Kruskal-Wallis, Mann-Whitney U tests. The data from surface roughness tests were statistically analyzed by multivariate analysis of variance and Bonferroni test (p < 0.05). Results: The B/T microhardness ratio results revealed no significant differences between groups (p > 0.05). Comparing the microhardness values of the composites' top surfaces before and after bleaching, a significant decrease was observed exclusively in FB30s (p < 0.05). No significant differences in surface roughness values were observed when the groups were compared based on bulk-fill materials (p > 0.05) while the polymerization time affected the surface roughness of the SF20s and SF30s groups (p < 0.05). After bleaching, surface roughness values were significantly increased in the SF20s and SF30s groups (p < 0.05). Conclusion: The clinicians should adhere to the polymerization time recommended by the manufacturer to ensure the durability of the composite material in the oral environment.


Assuntos
Clareadores/química , Resinas Compostas/efeitos da radiação , Resinas Compostas/química , Dureza , Humanos , Luz , Teste de Materiais , Microscopia Eletrônica de Varredura , Análise Multivariada , Polimerização/efeitos da radiação , Propriedades de Superfície , Fatores de Tempo
11.
Int J Pharm ; 565: 351-357, 2019 Jun 30.
Artigo em Inglês | MEDLINE | ID: mdl-31085254

RESUMO

In two recent Phase III clinical trials, use of a 25 mg dapivirine vaginal ring significantly reduced HIV acquisition rates. Post hoc analysis from one of the trials indicated higher rates of protection among women over the age of 21 years when compared to younger women, most likely due to reduced adherence in the latter group. There is currently no information available on how release of dapivirine from the ring is affected by either its intermittent removal from the vagina or women's cleaning of the ring before re-insertion. Here, in vitro drug stability and product performance characteristics of the dapivirine ring were assessed under simulated conditions of real-world use. The impact of systematic deviations from the 28-day continuous use protocol upon in vitro release performance, was investigated. Also, the effect of ring exposure to a range of common household chemicals - including bath salts, bleach, detergent and personal lubricants - was examined through measurement of dapivirine content and stability. Dapivirine in vitro release under intermittent schedules was similar to that obtained under the normal continuous schedule ignoring the periods of interruption. Ring exposure to various household chemicals had no discernible impact on dapivirine assay value, degradation or stability.


Assuntos
Fármacos Anti-HIV/química , Dispositivos Anticoncepcionais Femininos , Pirimidinas/química , Clareadores , Liberação Controlada de Fármacos , Estabilidade de Medicamentos , Produtos Domésticos , Lubrificantes
12.
Br J Biomed Sci ; 76(4): 172-177, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31144600

RESUMO

Background: The diagnosis of heavily pigmented melanocytic lesions is problematic. This is often compounded by lack of visibility of nuclear detail of tumour cells due to physical masking by melanin pigment. Similarly, there can be colour merging of chromogenic final reaction products with melanin, making an evidence of antigenic localisation problematic. There are a number of melanin bleaching techniques available for immunohistochemical assessments.Material and methods: All methods to date have involved the bleaching of melanin as a manually performed primary step before loading subsequently bleached slides onto automated immunohistochemical platforms. Here we define a semi-automated bleaching procedure that allows full integration on one of the most widely employed automated IHC staining platforms (Roche Ventana BenchMark Ultra). The bleaching protocol was defined on the BenchMark Ultra and involved the assessment of 24 histological cases of heavily pigmented malignant melanoma lesions (13 cutaneous and 11 metastatic) routinely fixed processed and paraffin wax embedded.Results: Completion of the bleaching was assessed on H&E preparations performed following the semi-automated bleaching step and employing the Roche Ventana BenchMark Ultra machine for 60 min at 42°C. Complete immunohistochemical staining was achieved on the automated platform within 5-6 h including the bleaching step. Results were consistent across all tissue evaluated.Discussion: This data provides evidence that the hydrogen peroxide bleaching procedure can be adapted for integration on one of the most widely employed automated IHC staining platforms and as a result, improve the efficiency and reproducibility of the technique.


Assuntos
Automação Laboratorial/normas , Clareadores/química , Peróxido de Hidrogênio/química , Imuno-Histoquímica/normas , Melaninas/química , Melanoma/diagnóstico , Neoplasias Cutâneas/diagnóstico , Anticorpos/química , Amarelo de Eosina-(YS) , Hematoxilina , Humanos , Melaninas/biossíntese , Melanócitos/química , Melanócitos/patologia , Melanoma/patologia , Neoplasias Cutâneas/patologia
14.
Redox Biol ; 24: 101207, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-31102971

RESUMO

Carbonate radicals (CO3-) are generated by the bicarbonate-dependent peroxidase activity of cytosolic superoxide dismutase (Cu,Zn-SOD, SOD-1). The present work explored the use of bleaching of pyrogallol red (PGR) dye to quantify the rate of CO3- formation from bovine and human SOD-1 (bSOD-1 and hSOD-1, respectively). This approach was compared to previously reported methods using electron paramagnetic resonance spin trapping with DMPO, and the oxidation of ABTS (2,2-azino-bis(3-ethylbenzothiazoline)-6-sulfonic acid). The kinetics of PGR consumption elicited by CO3- was followed by visible spectrophotometry. Solutions containing PGR (5-200 µM), SOD-1 (0.3-3 µM), H2O2 (2 mM) in bicarbonate buffer (200 mM, pH 7.4) showed a rapid loss of the PGR absorption band centered at 540 nm. The initial consumption rate (Ri) gave values independent of the initial PGR concentration allowing an estimate to be made of the rate of CO3- release of 24.6 ±â€¯4.3 µM min-1 for 3 µM bSOD-1. Both bSOD-1 and hSOD-1 showed a similar peroxidase activity, with enzymatic inactivation occurring over a period of 20 min. The single Trp residue (Trp32) present in hSOD-1 was rapidly consumed (initial consumption rate 1.2 ±â€¯0.1 µM min-1) with this occurring more rapidly than hSOD-1 inactivation, suggesting that these processes are not directly related. Added free Trp was rapidly oxidized in competition with PGR. These data indicate that PGR reacts rapidly and efficiently with CO3- resulting from the peroxidase activity of SOD-1, and that PGR-bleaching is a simple, fast and cheap method to quantify CO3- release from bSOD-1 and hSOD-1 peroxidase activity.


Assuntos
Bicarbonatos/química , Clareadores/química , Carbonatos/química , Radicais Livres/química , Pirogalol/análogos & derivados , Superóxido Dismutase-1/química , Bicarbonatos/metabolismo , Carbonatos/metabolismo , Radicais Livres/metabolismo , Oxirredução , Pirogalol/química , Análise Espectral , Superóxido Dismutase-1/metabolismo
16.
J Esthet Restor Dent ; 31(5): 451-456, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-30907068

RESUMO

OBJECTIVE: This study evaluated the influence of carbamide peroxide, 10% and 16%, on the surface roughness and gloss of a pressable ceramic. MATERIALS AND METHODS: Carbamide peroxide (10% or 16%) was applied for 4 hours or 3 hours per day for 14 days, respectively, in pressable ceramic discs (14 mm × 2 mm). Specimens were stored in distilled water at 37°C. Surface roughness and gloss were determined before carbamide peroxide application (T0 ), 7 days (T7 ) and 14 days (T14 ) after the initial treatment. ANOVA was used with repeated measures and multiple comparisons with a Bonferroni adjustment (P < 0.005). RESULTS: Significant increase in surface roughness was observed over time (P < 0.001), with T0 < T7 < T14 . When the gloss was analyzed, significant differences were found (P < 0.001), control group showed a higher gloss than those of the 10% and 16% groups. Significant decrease in gloss was observed over time (P < 0.001), with T0 > T7 > T14 . CONCLUSIONS: The surface roughness of pressable ceramics increased, while their gloss significantly decreased when 10% or 16% carbamide peroxide was applied. The specimens treated with 16% carbamide peroxide exhibited higher surface roughness and less gloss than the specimens treated with 10% carbamide peroxide. CLINICAL SIGNIFICANCE: This study found that carbamide peroxide gels commonly used in at-home procedures influenced the surface roughness and gloss of a pressable ceramic that is often used for rehabilitation esthetics.


Assuntos
Clareadores , Clareamento Dental , Peróxido de Carbamida , Cerâmica , Combinação de Medicamentos , Teste de Materiais , Peróxidos , Propriedades de Superfície , Ureia
17.
Odontology ; 107(4): 465-472, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-30895486

RESUMO

Bleaching agents may affect surface properties of mineral trioxide aggregate (MTA) as a coronal barrier. The purpose of this study was to investigate surface properties of MTA after exposure to intracoronal bleaching agents. MTA was set in acrylic molds with a 4 mm high central hole and a 6 mm diameter. Specimens were divided into four groups (n = 10); three groups were exposed to bleaching agents three times on every fourth day (carbamide peroxide-CP, hydrogen peroxide-HP, sodium perborate-SP) and a control group-C. The surface roughness and Vickers surface microhardness were measured. Differences between groups were analyzed using a Kruskal-Wallis test and intergroup comparisons were assessed with a Mann-Whitney U test with a Bonferroni correction (p < 0.0001). The microstructure and elemental composition were observed using a scanning electron microscope (SEM) and an energy-dispersive X-ray microanalysis (EDX) system. In terms of microhardness, the decrease in the HP group was significantly greater than that of the CP and SP groups; CP group significantly greater than that of the SP group, however, there was no significant difference between the SP and C groups. Surface roughness values were compared between groups, and no significant differences were observed between the CP and HP groups, and they exhibited significantly higher roughness values than the SP and C groups. SEM/EDX showed that the bleaching agents affected the elemental distribution. Bleaching agents adversely affected the surface roughness, surface microhardness and elemental distribution of MTA, with exposure to SP causing fewer changes on the surface properties than CP or HP.


Assuntos
Clareadores , Clareadores Dentários , Clareamento Dental , Compostos de Alumínio , Compostos de Cálcio , Combinação de Medicamentos , Peróxido de Hidrogênio , Óxidos , Peróxidos , Silicatos , Propriedades de Superfície , Ureia
18.
Molecules ; 24(4)2019 Feb 21.
Artigo em Inglês | MEDLINE | ID: mdl-30795539

RESUMO

Although melanin production is a key self-defense mechanism against ultraviolet radiation (UVR)-induced skin damage, uneven or excessive deposition of melanin causes hyperpigmentary disorders. Currently available whitening agents are unsatisfactory because of issues with efficacy and safety. To develop more effective depigmenting agents, we performed high-throughput melanin content assay screening using the B16F10 melanoma cell line and identified L-765,314 as a drug that suppressed melanin production in cultured melanocytes in a dose-dependent manner as well as cAMP- or 12-O-tetradecanoylphorbol 13-acetate (TPA)-stimulated melanin production without cytotoxicity. Interestingly, melanogenic gene expression was not altered by L-765,314. Rather, diminished melanin production by L-765,314 appeared to be caused by downregulation of tyrosinase activity via inhibition of protein kinase C (PKC). Because L-765,314 did not show any adverse effect in melanocytes, altogether our data suggest that L-765,314 could be a potential therapeutic candidate for skin hyperpigmentary disorders and further discovery of selective inhibitors targeting PKC might be a promising strategy for the development of depigmenting agents to treat hyperpigmentary disorders.


Assuntos
Clareadores/farmacologia , Inibidores Enzimáticos/farmacologia , Melaninas/antagonistas & inibidores , Monofenol Mono-Oxigenase/antagonistas & inibidores , Prazosina/análogos & derivados , Proteína Quinase C/antagonistas & inibidores , Bibliotecas de Moléculas Pequenas/farmacologia , Animais , Clareadores/química , AMP Cíclico/farmacologia , Relação Dose-Resposta a Droga , Inibidores Enzimáticos/química , Regulação da Expressão Gênica , Ensaios de Triagem em Larga Escala , Melaninas/biossíntese , Melanoma Experimental/genética , Melanoma Experimental/metabolismo , Melanoma Experimental/patologia , Camundongos , Monofenol Mono-Oxigenase/genética , Monofenol Mono-Oxigenase/metabolismo , Prazosina/química , Prazosina/farmacologia , Proteína Quinase C/genética , Proteína Quinase C/metabolismo , Transdução de Sinais , Bibliotecas de Moléculas Pequenas/química , Acetato de Tetradecanoilforbol/farmacologia , Células Tumorais Cultivadas
20.
J Oral Sci ; 61(1): 103-110, 2019 Mar 28.
Artigo em Inglês | MEDLINE | ID: mdl-30713266

RESUMO

The bleaching efficacy of common bleaching agents and deionized water treated with non-thermal atmospheric pressure plasma in the pulp chamber for nonvital tooth bleaching was evaluated. A total of 120 extracted human maxillary first incisors were stained using human blood. Teeth were randomly divided into eight groups (n = 15). In the first four groups, teeth were bleached using 35% hydrogen peroxide gel, 37% carbamide peroxide gel, 2:1 (w/v) sodium perborate paste, and deionized water for 30 min. In the remaining groups, bleaching agents were treated with non-thermal atmospheric plasma for 5 min inside the pulp chamber. Overall color changes (∆E) were determined using Commission Internationale de L'Eclairage Lab Colour System. The plasma-assisted tooth bleaching has not increased tooth temperature beyond 37°C. Bleaching efficacies of bleaching agents were significantly improved when treated with non-thermal atmospheric plasma compared to their application (P < 0.05). A remarkable bleaching effect was obtained when bleaching agents were substituted with water and when treated with non-thermal atmospheric plasma. Non-thermal atmospheric plasma treatment could be a novel tool for activation of bleaching agents in the pulp chamber for nonvital tooth bleaching procedure. Moreover, water could be used as a novel bleaching agent when treated with the non-thermal atmospheric plasma to eliminate possible risks which might arise from peroxide-containing agents.


Assuntos
Clareadores/química , Clareamento Dental/métodos , Dente não Vital , Peróxido de Carbamida/química , Humanos , Peróxido de Hidrogênio/química
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