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J Environ Manage ; 273: 111143, 2020 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-32734894


Environmental concerns have been raised regarding the intense contamination of water resources. Currently, numerous contaminants that reach water bodies are not efficiently removed by conventional water treatment methods. Therefore, there arises the need for development and optimization of efficient treatment methods for the removal of such recalcitrant contaminants. Given the circumstances, the present study aims to use of advanced oxidative processes for dye degradation. For this purpose, copper and zinc doped cobalt ferrites were synthesized by coprecipitation, targeting the degradation of methylene blue dye. The photocatalysts were characterized by XRD, WD-XRF, FE-SEM, N2 physisorption isotherms, UV-Vis diffuse reflectance spectroscopy, molecular fluorescence spectroscopy and zeta potential. According to the investigation of the degradation mechanism, the holes and hydroxyl radicals were mainly responsible for the dye's degradation. The obtained photocatalysts displayed promising results with up to 99% of dye degradation, employing conventional visible LED lamps, making the practical use of the catalyst highly viable, as well as the economic matters. Additionally, the synthesized materials' magnetic properties allowed total and efficient separation of the catalyst for its reutilization up to 4 cycles, with no decrease in photocatalytic activity and with low leaching of iron ions to solution.

Braz Dent J ; 31(3): 236-243, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32667516


This study aimed to quantify the penetration of hydrogen peroxide, color change evaluation, surface morphology, and composition after application of desensitizing agents before in-office bleaching. Fifty premolars were sectioned, an acetate buffer was placed in the pulp chamber and divided into five groups (n=10). In the positive control group, only the in-office bleaching gel was used, and in the negative control group, no treatment was used. Three different desensitizing agents were applied: Desensibilize KF2%® group; Mi Paste® group, and Desensibilize Nano-P® group. The bleaching procedure was carried out with 35% HP. The absorbance of the resulting solution was determined in a spectrophotometer. Color change was assessed by using a digital spectrophotometer. Four additional premolars were assigned to the same groups above for analysis under scanning electron microscope, as well as to evaluate the elemental composition with X-ray dispersive energy spectrometry. Data were subjected to ANOVA and Tukey's test (α=0.05). All products reduced the penetration of HP in the pulp chamber. Mi Paste and Nano P were the products that yielded the lowest HP penetration, which was similar to the negative control group (p<0.001). No significant difference was detected in color change (p<0.001). Concerning enamel morphology, the groups that were analyzed after bleaching were observed a greater deposition of desensitizing agents on the surface. The use of desensitizing agents before tooth bleaching seems to be an alternative to reduce adverse effects of the tooth.

Clareadores Dentários , Clareamento Dental , Esmalte Dentário , Cavidade Pulpar , Peróxido de Hidrogênio
Braz. dent. sci ; 23(2): 1-8, 2020. tab, ilus
Artigo em Inglês | LILACS, BBO - Odontologia | ID: biblio-1096444


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)

Clareamento Dental , Permeabilidade do Esmalte Dentário , Clareadores , Peróxido de Carbamida , Peróxido de Hidrogênio
J Dent ; 40 Suppl 2: e71-6, 2012 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-22713738


OBJECTIVES: Color match is one of the most important characteristics of aesthetic restorative materials. Integrity of the restoration and color stability throughout its functional duration are of paramount importance to ensure treatment longevity. These features, however, are not consistent among the different dental restorative materials. The purpose of this study was to evaluate the influence of professional prophylaxis on reducing wear discoloration of four aesthetic restorative materials after their immersion in coffee solution for 15 days. METHODS: Seventy-one disc-shaped specimens (17 mm in diameter and 1mm thick) were fabricated and divided into five groups according to each restorative material: direct composite resin (G1: Tetric Ceram(®)), three indirect composite resins (G2: Targis; G3: Resilab Master; G4: belleGlassTM HP) and one ceramic system (G5: control: IPS Empress(®) 2). The specimens were immersed in coffee staining solution for 15 days at 37° ± 1°C in a dark environment. Afterwards, they were subjected to professional prophylaxis using sodium bicarbonate jet. Evaluations were made by means of a reflectance spectrophotometer, at three time-intervals: baseline, immediately after staining (15 days), and after prophylaxis. Data were subjected to two-way ANOVA and post hoc Tukey's test (α=0.05). RESULTS: Significant difference was observed between G1/G3 and the other groups, between G2/G4 and the other groups, and between G5 and all the other groups. CONCLUSIONS: It was concluded that G1 and G3 showed the greatest color changes, followed by G2 and G4, while G5 showed the smallest changes. Professional prophylaxis seemed to minimize the wear discoloration, which might result in increasing aesthetic restoration longevity.

Resinas Compostas/química , Materiais Dentários/química , Porcelana Dentária/química , Profilaxia Dentária/métodos , Estética Dentária , Café/química , Cor , Detergentes/química , Cimentos de Ionômeros de Vidro/química , Humanos , Compostos de Lítio/química , Teste de Materiais , Metacrilatos/química , Cimento de Silicato/química , Bicarbonato de Sódio/química , Espectrofotometria/métodos , Propriedades de Superfície , Temperatura , Fatores de Tempo
J Prosthodont ; 20(8): 632-8, 2011 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-22040527


PURPOSE: Staining of prosthodontic materials may result in patient dissatisfaction and additional expense for replacement. This study aimed to determine the color stability of two heat-cured denture base acrylic (Lucitone 550, Vipi Cril) and one nylon denture base resin (Transflex) after immersion in beverages. MATERIALS AND METHODS: Forty disks of each resin (20.0-mm diameter, 3.0-mm thick) were prepared and stored in distilled water for 24 hours at 37°C. During that time (T(0) ), the color of all specimens was spectrophotometrically measured. Each specimen was immersed in coffee, cola, red wine, and distilled water as a means of control. After 15-day (T(1) ) and 30-day (T(2) ) periods of immersion, the color of the specimens was measured again. The CIE (Commission Internationale de L' Eclairage) L*a*b* system was used to determine mean ΔE (color changes) values for each material and compared statistically with two-way ANOVA and Bonferroni intervals at 0.95. RESULTS: In ΔET(0) T(1) and ΔET(0) T(2) the most severe staining was apparent with red wine (p < 0.001), followed by coffee (p < 0.01), when compared to the specimens stored in distilled water. Transflex also showed significant color change after immersion in cola (p < 0.01). In ΔET(1) T(2) only red wine promoted significant staining of all resins (p < 0.0001). CONCLUSION: Chromatic changes were exhibited by specimens immersed in red wine, followed by coffee. For Transflex, cola also promoted color changes. The values of color changes converted to National Bureau of Standard units showed them to be perceivable to the human eye.

Resinas Acrílicas , Bebidas , Cor , Bases de Dentadura , Nylons , Resinas Acrílicas/química , Colorimetria , Teste de Materiais , Nylons/química
Rev. odontol. UNESP (Online) ; 40(3)maio-jun. 2011. tab, ilus
Artigo em Português | LILACS-Express | LILACS | ID: lil-614432


O presente estudo analisou a alteração de cor e rugosidade superficial de um compósito utilizando quatro dentifrícios, desenvolvidos para estimular pacientes em sua higiene bucal. Utilizou-se um compósito microhíbrido,cor B1, e foram confeccionados 40 corpos de prova (cp). A seguir, os cp foram submetidos à avaliação inicial de cor em espectrofotômetro e de rugosidade inicial em rugosímetro digital. Os cp foram divididos em oito grupos (n = 5) para se realizar a escovação: G1e G5, dentifrício com flúor; G2 e G6, dentifrício com flúor + clorexidina; G3 e G7, dentifrício com flúor + evidenciador de placa + clorexidina; G4 e G8, dentifrício com flúor + evidenciador de placa. Esse teste foi realizado na máquina de escovação. Posteriormente, G1a G4 foram novamente submetidos à avaliação de cor e G5 a G8, de rugosidade final. ANOVA e pós-teste de Tukey (a = 0,05) demonstraram que as maiores médias (± desvio padrão) de variação de cor foram para G3 = 10,1(±6,4) e G4 = 8,6(±4,4), e as menores, para G1 = 0,8(±1,4) e G2 = 0,8(±0,8), com diferença significativa entre G1-G2 e G3-G4 (p < 0,0035). Para a rugosidade,ANOVA 2 fatores e pós-teste de Bonferroni (a = 0,05) mostraram diferença significativa (p < 0,0001) entre os valores de rugosidade (média ± desvio padrão) em mm antes (G5 = 0,7 ± 0,2; G6 = 0,8 ± 0,5; G7 = 0,6 ± 0,1; G8 = 0,5 ± 0,2) e após escovação (G5:1,4 ± 0,3; G6 = 1,4 ± 0,4; G7 = 1,5 ± 0,3; G8 = 1,2 ± 0,2) em todos os grupos. Concluiu-se que o evidenciador de placa demonstrou a maior alteração de cor no compósito e houve aumento significativo da rugosidade superficial após a escovação em todos os grupos.

This study evaluated the color stability and the surface roughness of a composite resin using four toothpastes developed to stimulate oral hygiene in persons. Methods: A hybrid composite resin, color B1, was used, and forty specimens were made. Subsequently, the specimens? colors were at first evaluated in a spectrophotomer and the initial roughness in a roughness meter. The specimens were then divided into 8 groups (n = 5): G1 and G5 toothpaste with fluoride; G2 and G6 toothpaste with chlorhexidine; G3 and G7 toothpaste with fluoride + plaquedisclosing (erythrosine) + chlorhexidine; G4 and G8 toothpaste with fluoride + plaque disclosing (erythrosine). This test was conducted in a mechanical toothbrushing machine. The specimens (G1 to G4) were again subjected to color evaluation and final roughness (G5 to G8). ANOVA and Tukey?s test (a = 0.05) showed that the highest values mean (±standard-deviation) went to G3 = 10.1 (±6.4) and G4 = 8.6 (±4.4) and the lowest to G1 = 0.8(±1.4) and G2 = 0.8(±0.8), with a significant difference between groups G1-G2 and G3-G4 (p < 0.0035). For surface roughness, 2-way ANOVA and Bonferroni?s test (a = 0.05) showed significant differences (p < 0.0001) between roughness values (mean ± standard- deviation) in mm before (G5 = 0.7 ± 0.2; G6 = 0.8 ± 0.5; G7 = 0.6 ± 0.1; G8 = 0.5 ± 0.2) and after (G5:1.4 ± 0.3; G6 = 1.4 ± 0.4; G7 = 1.5 ± 0.3; G8 = 1.2 ± 0.2) brushing for all groups. Conclusion: plaque disclosing showed the highest change of color in the composite resin and significant increase of superficial roughness happens after brushing in all the experimental groups.