At-home bleaching with carbamide peroxide with concentrations below 10%: bleaching efficacy and permeability in the pulp chamber.

OBJECTIVES: To evaluate the bleaching efficacy and permeability of hydrogen peroxide (HP) in the pulp chamber of human teeth bleached with lower concentrations of carbamide peroxide gel (4%, 5% and 7% CP). MATERIALS AND METHODS: Bleaching gels with lower concentrations were formulated and a commercial standard gel, 10% CP, was used as a reference. Fifty-six human premolars were randomly divided into four groups. Applications of the bleaching gel were made for 3 h for 21 days. The bleaching efficacy was evaluated by digital spectrophotometry on 1, 7, 14 and 21 days, with analysis in the ∆Eab, ∆E00 and WID color spaces. The concentration of HP in the pulp chamber was measured in the same periods by UV-Vis spectrophotometry (µg/mL). Two-way repeated analysis of variance (ANOVA) examined bleaching efficacy and HP permeability, followed by Tukey's post-hoc test (α = 0.05). RESULTS: All groups showed significant color changes, with no statistical differences after the second and third week of bleaching (p > 0.05). The 'time' factor was statistically different (p < 0.05), increasing the bleaching efficacy throughout the treatment. The 4% CP group had lower HP levels in the pulp chamber (p < 0.05). CONCLUSIONS: The results seem promising, revealing that low concentration gels are as effective as 10% CP with the benefit of reducing the amount of HP in the pulp chamber. CLINICAL RELEVANCE: Low concentration 4% PC and 5% PC maintains bleaching efficacy, reduces the penetration of HP peroxide into the pulp chamber, and may reduce tooth sensitivity.

Low and high hydrogen peroxide concentrations of in-office dental bleaching associated with violet light: an in vitro study.

OBJECTIVES: This study aims to assess hydrogen peroxide (HP) penetration within the pulp chamber, color change (CC), physical-chemical properties, and temperature using in-office different concentration bleaching gels with or without violet light. MATERIALS AND METHODS: Fifty teeth were divided into five groups (n = 10) based on the HP concentration bleaching gels used (6% and 35%) and the used violet light (with or without). HP penetration within the pulp chamber was measured using UV-Vis. The CC was evaluated with a digital spectrophotometer. Initial and final concentration, and pH were measured through titration, and a Digital pHmeter, respectively. Temperature analyses were measured through a thermocouple. Statistical analysis included two-way ANOVA, Tukey's, and Dunnett's test (α = 0.05). RESULTS: The presence of violet light did not affect the amount of HP within the pulp chamber, or the CC (p > 0.05). Greater penetration of HP was observed within the pulp chamber, as well as CC when using 35% HP (p < 0.05). The final concentration of both gels was lower than the initial concentration, regardless of the use of violet light (p < 0.05). The initial and final pH levels remained neutral and stable (p > 0.05). The pulp temperature increased when the gels were used in conjunction with violet light (p < 0.05). CONCLUSIONS: Using violet light in conjunction with 6% or 35% HP does not alter the physical properties of the bleaching agents, the penetration of HP or enhance color change. However, an increase in temperature was observed when violet light was applied associated with bleaching gels. CLINICAL RELEVANCE: While the simultaneous use of violet light with hydrogen peroxide 6% or 35% does not alter the material's properties, it also does not bring benefits in reducing hydrogen peroxide penetration and improving color change. Furthermore, the use of violet light increases pulp temperature.

Can all highly concentrated in-office bleaching gels be used as a single-application?

OBJECTIVE: This in vitro study aims to evaluate of hydrogen peroxide (HP) diffusion into the pulp chamber, bleaching efficacy (BE), and pH stability (pH) of single-application high concentrated in-office bleaching gels. MATERIALS AND METHODS: Eighty-eight healthy premolars were randomly into eleven groups (n = 8) according to the in-office dental bleaching: DSP White Clinic 35% calcium (DW), Nano White 35% (NW), Opalescence XTra Boost 40% (OB), Pola Office + 37.5% (PO), Potenza Bianco Pro SS 38% (PB), Total Blanc 35% (TB), Total Blanc One-Step 35% (TO), Whiteness Automixx 35% (WA), Whiteness Automixx Plus 35% (WP), and Whiteness HP Blue 35% (WB). A group not exposed to bleaching agents was the control group (CG). All bleaching agents were applied in one session with a single application. After the bleaching procedure, the concentration of HP diffusion (µg/mL) into the pulp chamber was assessed using UV-Vis spectrophotometry. The BE (ΔEab and ΔE00) was evaluated before and 1 week after the bleaching procedure using a digital spectrophotometer. The pH of each bleaching gel was evaluated by digital pHmeter. The one-way ANOVA and Tukey's was used for a statistical analysis (α = 0.05). RESULTS: The concentration of HP diffusion into the pulp chamber was higher in all in-office bleaching gels when compared to CG (p < 0.0000001). However, there are a significant difference between them (p = 0.0001). A significant BE was observed in all in-office bleaching gels (p < 0.0001 for ΔEab and ΔE00), with a significant difference between them (p < 0.0001). PO, OB, TB, WP, and WB showed a higher BE when compared to DW, PB, and WA (p < 0.0001). Most bleaching gels were slightly acidic or alkaline during the total application time, while DW, PB, TB, and WA showed a high acidic behavior after 30 min of application. CONCLUSIONS: A single application was able to produce a bleaching efficacy. However, usually, gels with slightly acidic or alkaline pH during the application time reduces the HP diffusion into the pulp chamber. CLINICAL RELEVANCE: The single-application of bleaching gels with slightly acidic or alkaline and stable pH decreased the penetration of hydrogen peroxide into the pulp chamber in in-office bleaching and maintained the bleaching efficacy.

Effects of microabrasion association to at-home bleaching on hydrogen peroxide penetration and color change.

PURPOSE: This study aimed to quantify the penetration of hydrogen peroxide (HP) inside the pulp cavity and color change with two different concentrations of HP to at-home bleaching associated or not with enamel microabrasion (MA). METHODS: Forty healthy premolars were randomly divided in four groups (n = 10): only HP4%, MA + HP4%, only HP10%, MA + HP10%. The concentration (µg/ml) of HP was assessed using UV-Vis spectrophotometry. The color change (ΔEab , ΔE00 and WID ) was evaluated before and one-week after bleaching. Data were evaluated for a two-way ANOVA and the Tukey's test (α = 0.05). RESULTS: The application of MA increased the amounts of HP inside the pulp chamber when compared to without MA, as well as PH10% when compared to PH4% (p < 0.0001). PH10% showed higher WID when compared to PH4%. No significant difference was observed when ΔEab , and ΔE00 were used. CONCLUSIONS: The enamel MA before at-home bleaching promotes greater penetration of HP, although this procedure did not significantly affect the color change. CLINICAL SIGNIFICANCE: Since greater penetration of HP into the pulp chamber was detected when home bleaching was applied immediately after MA, the clinician should not apply home bleaching gels in the same session when MA was performed.

Synthesis of zeolites from residual diatomite using a microwave-assisted hydrothermal method.

Population growth directly affects the industrial production sector, as well as the quantities of waste generated in this sector. Diatomite is a typical example of such industrial waste and is used for the filtration of various products. With the aim of increasing its value, the present study employs this residue, following its usage in beer filtration, as a silicon source for the synthesis of zeolites. Two synthetic routes are used, namely, hydrothermal treatment with and without a pre-treatment step in a conventional microwave for 3-24 h. The results of the compositional and morphological characterization show that the use of a few minutes of microwave radiation reduces the process of zeolite synthesis to 15 h compared to the synthesis without pre-treatment, as well as reducing the production costs. The efficiency of microwave radiation is assessed with regards to solubilizing the residue, the possibility of employing a device of conventional use and the possibility of putting to use the diatomite residue, turning it into a versatile material that can be applied in several areas and process, such as industrial catalysts, the adsorption of environmental pollutants (ions and molecules) and water treatment via ion-exchange resins.

Visible light activated magnetic photocatalysts for water treatment.

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.

Effect of Prior Application of Desensitizing Agent on the Teeth Submitted to In-Office Bleaching.

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.

Effect of prior application of desensitizing agent on the teeth submitted to in-office bleaching

Abstract 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.

Resumo Este estudo teve como objetivo quantificar a permeabilidade do peróxido de hidrogênio (PH), avaliação da mudança de cor, morfologia da superfície e composição de elementos após a aplicação de agentes dessensibilizantes antes do clareamento em consultório. Cinquenta pré-molares foram seccionados, um tampão de acetato foi colocado na câmara pulpar e divididos em cinco grupos (n=10). No grupo controle positivo, apenas o gel clareador em consultório foi utilizado e no grupo controle negativo nenhum tratamento foi realizado. Foram aplicados três agentes dessensibilizantes diferentes: grupo KF2%®; grupo Mi Paste® e Desensibilize Nano-P®. O procedimento de clareamento foi realizado com PH a 35%. A absorbância da solução resultante foi determinada em um espectrofotômetro. A mudança de cor foi avaliada utilizando um espectrofotômetro digital. Quatro pré-molares adicionais foram atribuídos aos mesmos grupos acima para análise em microscópio eletrônico de varredura, bem como para avaliar a composição elementar com espectrometria de energia dispersiva por raios-X. Os dados foram submetidos ao teste ANOVA e Tukey (a=0,05). Todos os produtos reduziram a penetração de PH na câmara pulpar. Mi Paste e Nano P foram os produtos que apresentaram a menor penetração de PH, semelhante ao grupo controle negativo (p<0,001). Nenhuma diferença significativa foi detectada na mudança de cor (p<0,001). Em relação à morfologia do esmalte, os grupos analisados após o clareamento apresentou maior deposição de agentes dessensibilizantes na superfície. O uso de agentes dessensibilizantes antes do clareamento dental parece ser uma alternativa para reduzir os efeitos adversos no dente.

Initial and pulp chamber concentration of hydrogen peroxide using different bleaching products / Concentração de peróxido de hidrogênio na câmara pulpar utilizando diferentes produtos clareadores

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)

Influence of professional prophylaxis on reducing discoloration of different aesthetic restorative materials.

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.

Color stability of resins and nylon as denture base material in beverages.

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.

Efeito de diferentes dentifrícios contendo evidenciador de placa e clorexidina na estabilidade de cor e rugosidade superficial de uma resina composta / Effect of different dentifrices containing plaque disclosing and chlorhexidine in color stability and surface roughness of a composite resin

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.