Efeito de diferentes meios de imersão na emissão fluorescente de resinas compostas

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Maturação in vitro de oócitos bovinos em meios suplementados com quercetina e seu efeito sobre o desenvolvimento embrionário

A quercetina é um flavonoide, amplamente encontrada em frutas, vegetais, grãos, flores, com elevada concentração no vinho tinto, e tem sido caracterizada funcionalmente pela atividade antioxidante. Para avaliação da maturação nuclear e do desenvolvimento embrionário bovino, os oócitos foram maturados por 22h na presença de quercetina (0,4, 2, 10 e 50µM), cisteamina (100µM) e na ausência dos antioxidantes. Os oócitos maturados foram corados com Hoechst para avaliação da maturação in vitro. Para avaliação do desenvolvimento embrionário, os oócitos foram fertilizados e cultivados in vitro, as taxas de desenvolvimento embrionário foram determinadas no sétimo dia de cultivo e o percentual de eclosão e o número de células dos embriões no oitavo dia. Os níveis de glutationa (GSH) dos oócitos foram mensurados por emissão de fluorescência com CMF₂HC. A porcentagem de maturação nuclear (±89%) não diferiu entre os grupos. O desenvolvimento embrionário variou entre os tratamentos, o percentual de blastocisto foi superior (P<0,05) nos grupos tratados com 0,4, 2, 10 e 50∝M de quercetina (56,9, 59,5, 53,6 e 49,6%, respectivamente) e com 100∝M de cisteamina (50,4%) em relação ao grupo controle (42,3%). Na comparação entre os dois antioxidantes, a quercetina (0,4 e 2µM) foi superior na produção de embriões (56,9 e 59,5%, respectivamente) em comparação com cisteamina (50,4%). As taxas de embriões eclodidos foram similares (P>0,05) entre os grupos (±63,0%). O número médio de células dos embriões também foi similar entre os grupos (±233). Os níveis intracelulares de GSH foram superiores nos oócitos maturados com cisteamina, mas similares entre os oócitos tratados com quercetina e o controle. A suplementação da maturação in vitro com antioxidantes melhora as taxas de blastocistos. A quercetina foi superior à cisteamina, que, por sua vez, foi superior ao controle. Mas os níveis de GSH foram superiores somente nos oócitos tratados com cisteamina.

Preparação, caracterização e aplicação de carbono polimérico vítreo em sensores eletroquímicos

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Color Stability of Resin Used for Caries Infiltration After Exposure to Different Staining Solutions

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Mineral loss and color change of enamel after bleaching and staining solutions combination

Pigments of food and beverages could affect dental bleaching efficacy. The aim of this investigation was to evaluate color change and mineral loss of tooth enamel as well as the influence of staining solutions normally used by adolescent patients undergoing home bleaching. Initial hardness and baseline color were measured on enamel blocks. Specimens were divided into five groups (n = 5): G1 (control) specimens were kept in artificial saliva throughout the experiment (3 weeks); G2 enamel was exposed to 10% carbamide peroxide for 6 h daily, and after this period, the teeth were cleaned and stored in artificial saliva until the next bleaching session; and G3, G4, and G5 received the same treatments as G2, but after bleaching, they were stored for 1 h in cola soft drink, melted chocolate, or red wine, respectively. Mineral loss was obtained by the percentage of hardness reduction, and color change was determined by the difference between the data obtained before and after treatments. Data were subjected to analysis of variance and Fisher's test (a = 0.05). G3 and G5 showed higher mineral loss (92.96 +/- 5.50 and 94.46 +/- 1.00, respectively) compared to the other groups (p = 0.05). G5 showed high-color change (9.34 +/- 2.90), whereas G1 presented lower color change (2.22 +/- 0.44) (p = 0.05). Acidic drinks cause mineral loss of the enamel, which could modify the surface and reduce staining resistance after bleaching. (C) 2013 Society of Photo-Optical Instrumentation Engineers (SPIE)

Effect of Beverages and Mouthwashes on the Hardness of Polymers Used in Intraoral Prostheses

PurposeThe mechanical properties of acrylic resins used in intraoral prostheses may be altered by frequent exposure to liquids such as beverages and mouthwashes. This study aimed to evaluate the effect of thermocycling and liquid immersion on the hardness of four brands of acrylic resins commonly used in removable prostheses (Onda Cryl, QC-20, Classico, Lucitone).Materials and MethodsFor each brand of resin, seven specimens were immersed in each of six solutions (coffee, cola, red wine, Plax-Colgate, Listerine [LI], Oral B), and seven more were placed in artificial saliva (control). The hardness was tested using a microhardness tester before and after 5000 thermocycles and after 1, 3, 24, 48, and 96 hours of immersion. The results were analyzed using three-way repeated-measures ANOVA and Tukey's test (p < 0.05).ResultsThe hardness of the resins decreased following thermocycling and immersion in the solutions. Specimens immersed in cola and wine exhibited significant decreases in hardness after immersion for 96 hours, although the greatest significant decrease in hardness occurred in specimens immersed in LI. However, according to American Dental Association specification 12, the Knoop hardness of acrylic resins for intraoral prostheses should not be below 15. Thus, the median values of superficial hardness observed in most of the acrylic resins in this study are considered clinically acceptable.ConclusionsThe microhardness of polymers used for intraoral prostheses decreases following thermocycling. Among specimens immersed in beverages, those immersed in cola or wine experienced the greatest decrease in microhardness. Immersion of acrylic resins in LI significantly decreased the microhardness in relation to the initial value. Among the resins assessed, QC-20 exhibited the lowest initial hardness.

Efeito da escovação dentária no manchamento de braquetes estéticos cerâmicos

Objective: this study aimed to analyze the in vitro effect of brushing on the color stability of ceramic brackets immersed in dye solutions. Materials and Methods: seven ceramic brackets of four commercial brands were tested: two monocrystalline and two polycrystalline. The parameters of color were obtained by spectrophotometer before and after 21 days of immersion of the brackets in coffee, red wine, Coca-Cola, black tea and artificial saliva. Another group of brackets of each brand were also immersed in the same solutions and for an equal time to the previous group, but with intervals of daily brushing performed by a toothbrushing machine (Mavtec). The data were evaluated by analysis of variance, multiple comparison tests for means and Student's t-test. Results: the mean color change of the brackets without brushing ranged from 0.46 to 7.61, while in the group with brushing these means ranged from 0.36 to 2.50. The staining still remained noticeable (change of color greater than 3.7) for all brackets when immersed in black tea. Conclusion: daily brushing helped significantly in the color stability of ceramic brackets, maintaining the color change to levels considered not visible to the human eye, except for the solution of black tea in which the staining remained relevant.

Effect of staining agents on color change of composites

Composite resins are materials that can present color changing when exposed to pigments. Objective: The aim of this study was to evaluate, in vitro, the color changing of composites after immersion in different substances for different periods. Material and methods: Two microhybrid composite resins: Charisma (Heraeus – Kulzer) and Opallis (FGM) were used. Red wine and acai pulp were also used as immersion medium. For this study, 32 specimens with 10 mm of diameter and 2 mm of thickness were used, divided into 4 groups: Group 1 – Opallis composite immersed in red wine solution; Group 2 – Opallis composite immersed in acai berry pulp solution; Group 3 – Charisma composite immersed in red wine solution; Group 4 – Charisma composite immersed in acai berry pulp solution. The specimens were evaluated in the following time periods: T0 – baseline, T1 – 24 hours, T2 – 48 hours, T3 – 72 hours and T4 – 96 hours. For the assessment of staining, a spectrophotometer for colorimetry was used (Color Guide 45 / 0, PCB 6807 BYK-Gardner Gerestsried GmBH, Germany), and the values obtained were transferred to a computer and recorded according to CIELAB system. Results: The data were evaluated using Kruskal- Wallis non-parametric tests with the following mean values for the immersion periods of 24, 48, 72 and 96 hours, respectively: G1 – 7.35, 7.84, 9.04,10.48; G2 – 2.92, 4.15, 4.30, 4.64; G3 – 3.14, 7.35, 8.13, 8.43, G4 – 4.49, 5.99, 6.92, 6.76. Conclusion: Red wine showed a higher tendency toward altering the composite color than acai berry pulp. In addition, no significant difference was found concerning to the behavior of the two composite resins. Concerning to the immersion time periods, significant differences were only observed among the groups in the 24 hour time period.

Colour stability of acrylic resin denture teeth after immersion in different beverages

The colour stability of acrylic resin denture teeth in beverages was investigated. A spectrophotometer measured the colour (CIE-L*a*b* system) of all specimens after storage in distilled water for 24 h at 37°C (T0). Specimens were then immersed in various beverages. After 15 days (T1) and 30 days (T2), for each material, the mean ∆E values were calculated and compared by two-way ANOVA and Tukey intervals (α=0.05). In the ∆T0T1 period, specimens stored in red wine were significantly discoloured, compared to distilled water (P=0.003). There was no difference between immersion solutions in ∆ET0T2 (P=0.772) and in ∆ET1T2 (P=0.058), and no difference between materials in all immersion periods.

In vitro study of color stability of polycrystalline and monocrystalline ceramic brackets

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Desenvolvimento de modelos para flavonoides e cumarinas utilizando o campo de força CGenFF

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Fluorescence Intensity of Composite Layering Combined with Surface Sealant Submitted to Staining Solutions

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Alteração cromática de resinas compostas laboratoriais submetidas à imersão em diferentes soluções

The pigmentation of indirect composite resins has been one of the most common reasons that lead the restorative treatment to failure. The purpose of this study was to investigate the effect of different solutions on color stability of indirect composite resins. Five brands of indirect composite resins were tested: Adoro, Resilab, Cristobal, Sinfony and Epricord. The samples were immerged in eleven solutions (n=10): common liquid foods (coke soft drink, red wine, coffee and orange juice), mounthrinses (Listerine, Oral-B, Colgate Plax and Periogard) and bleaching agents (carbamide peroxide 16%, 7.5% and hydrogen peroxide 38%) and artificial saliva (control group). The color was measured by a spectrophotometer before and after 7, 14 and 21 days of immersion in common liquid foods, after 12, 24, 36 and 60 hours of immersion in mounthrinses and after 7 and 14 days of immersion in bleaching agents. The Cristobal and Adoro resins showed highest values of ΔE statistically significant compared to the others resin brands. Adoro’s ΔE values changed significantly after the immersion process in red wine and coffee and also between periods measured. The resins Cristobal and Sinfony showed the highest values of ΔE after the immersion process in Listerine with difference statistically significant in comparison to control group. Besides, there was difference statistically significant of the ΔE values  for  Cristobal  after  immersion  in hydrogen peroxide 7,5% in comparison to control group. It can be conclude that all the solutions promoted color change on the indirect composite resins. However, ΔE values  are  whitin  the  values clinically acceptable.

Effect of different solutions on knoop hardness of indirect composite

Introduction: Indirect dental composites may have adequate clinical performance. However, the literature is scarce regarding indirect composite resins and these solutions should be considered to maintain their properties. The aim of the study was to evaluate the influence of beverages, mouthwashes and bleaching agents on the hardness of indirect composite resins. Methods: Five different brands of indirect composite resins were evaluated: Adoro, Resilab, Cristobal, Sinfony and Epricord. Ten specimens of each brand were immersed in eleven different solutions: four mouthwashes (Listerine, Oral-B, Plax, Periogard), four beverages (coke soft drink, red wine, coffee, orange juice), three dental bleaching agents (16% peroxide of carbamide, 7.5% and 38% peroxide of hydrogen) and artificial saliva (control group). The Knoop hardness was measured before (baseline) and after 12, 24, 36 and 60 hours of immersion in mouthwashes; after 7, 14 and 21 days of immersion in beverages and after 7 and 14 days of immersion in dental bleaching agents. The results were analyzed using 3-way repeated measures ANOVA and Tukey’s test (p<0.05). Results: All resins presented significant decrease on hardness values after immersion process whereas this reduction was higher for Resilab and Sinfony. The latter exhibited the lowest initial values of hardness while Cristobol resin presented the highest hardness values. The mouthwashes promoted a significant decrease in the hardness of specimens.

Vinificação em tinto de uvas americanas: efeito das técnicas de pré-secagem das uvas e de chapéu submerso nos perfis químico e sensorial

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)