Knoop Hardness Of Composites Cured With Halogen And Led Lightcuring Units In Class I Restorations

Aim: To evaluate the effect of light-curing units (LCUs) on the microhardness of class I composite restorations at different depths. Methods: Two light emitting diodes (LED) (Freelight 2, Radii) and one halogen (Optilux 501) LCUs were evaluated. Thirty class I cavities prepared in human third molars were restored with a microhybrid (Charisma) and a microfilled (Renamel) resin composite. After seven days of water storage, the teeth were decoronated and the crowns were bisected mesiodistally and tested for microhardness under a 25 g load for 20 seconds. Fifteen indentations were performed at three depths for each half-crown. Results: Charisma presented significantly higher Knoop hardness number (KHN) values than Renamel. At the superficial depth, there were no statistically significant differences (p > 0.05) when Charisma was cured with both LED curing units. However, statistically significant difference (p < 0.05) was found when Charisma was light-cured with the halogen LCU. The lowest KHN value was obtained by Renamel light-cured with both LED LCUs, regardless of the composite. Nevertheless, when the microfilled composite was light-cured with the halogen LCU, hardness was significantly higher compared to those cured with LED units at all evaluated depths. Conclusions: The effectiveness of polymerization is related not only to the light-curing source, but also to the type of composite and the curing depth.8130-3

Knoop hardness of composites cured with halogen and led light-curing units in class I restorations

Aim: To evaluate the effect of light-curing units (LCUs) on the microhardness of class I composite restorations at different depths. Methods: Two light emitting diodes (LED) (Freelight 2, Radii) and one halogen (Optilux 501) LCUs were evaluated. Thirty class I cavities prepared in human third molars were restored with a microhybrid (Charisma) and a microfilled (Renamel) resin composite. After seven days of water storage, the teeth were decoronated and the crowns were bisected mesiodistally and tested for microhardness under a 25 g load for 20 seconds. Fifteen indentations were performed at three depths for each half-crown. Results: Charisma presented significantly higher Knoop hardness number (KHN) values than Renamel. At the superficial depth, there were no statistically significant differences (p > 0.05) when Charisma was cured with both LED curing units. However, statistically significant difference (p < 0.05) was found when Charisma was light-cured with the halogen LCU. The lowest KHN value was obtained by Renamel light-cured with both LED LCUs, regardless of the composite. Nevertheless, when the microfilled composite was light-cured with the halogen LCU, hardness was significantly higher compared to those cured with LED units at all evaluated depths. Conclusions: The effectiveness of polymerization is related not only to the light-curing source, but also to the type of composite and the curing depth

Knoop hardness of composites cured with halogen and led light-curing units in class I restorations

evaluate the effect of light-curing units (LCUs) on the microhardness of class I composite restorations at different depths. Methods: Two light emitting diodes (LED) (Freelight 2, Radii) and one halogen (Optilux 501) LCUs were evaluated. Thirty class I cavities prepared in human third molars were restored with a microhybrid (Charisma) and a microfilled (Renamel) resin composite. After seven days of water storage, the teeth were decoronated and the crowns were bisected mesiodistally and tested for microhardness under a 25 g load for 20 seconds. Fifteen in¬dentations were performed at three depths for each half-crown. Results: Charisma presented significantly higher Knoop hardness number (KHN) values than Renamel. At the superficial depth, there were no statistically signifi¬cant differences (p > 0.05) when Charisma was cured with both LED curing units. However, statistically significant difference (p < 0.05) was found when Charisma was light-cured with the halogen LCU. The lowest KHN value was obtained by Renamel light-cured with both LED LCUs, regardless of the composite. Nevertheless, when the microfilled composite was light-cured with the halogen LCU, hardness was significantly higher compared to those cured with LED units at all evaluated depths. Conclusions: The effectiveness of polymerization is related not only to the light-curing source, but also to the type of composite and the curing depth

Influence Of Light-activation Protocol On Methacrylate Resin-composite Evaluated By Dynamic Mechanical Analysis And Degree Of Conversion.

The aim of this study was to evaluate the degree of conversion (DC) and to identify the viscoelastic properties: storage modulus (E'), loss modulus (E), tangent delta (tan δ), and glass transition temperature (T g ) of a microhybrid resin-composite light-activated by three different protocols. A Filtek Z250 (3 M ESPE) shade A3 was inserted in a Teflon mold (21 mm × 5 mm × 1 mm for viscoelastic properties; and 5 mm × 1 mm for DC) and light-activated according to the following light-activation protocols: (S) 1,000 mW/cm(2) × 19 s, (HP) 1,400 mW/cm(2) × 14 s, and (PE) 3,200 mW/cm(2) × 6 s, all set up to deliver 19 J/cm(2). Viscoelastic properties was assessed by dynamic mechanical analysis (DMA) (n = 3), performed in single cantilever clamped mode. DC (n = 5) was measured by FTIR on top (T) and bottom (B) surfaces, and the data was submitted to a split-plot one-way ANOVA. For DC, there was a significant effect for surface factor and light-activation protocols factor. Top surface showed higher DC than B in all experimental conditions. Light-activation protocols S and HP resulted in higher DC than PE and were similar between them. Viscoelastic properties (E', E, tan δ, T g ) were not affected by light-activation protocols. It could be concluded that light-activation protocols influenced DC but not influenced the viscoelastic properties

Ser e parecer: indumentária e hierarquia social na sátira de frei Lucas de Santa Catarina, Portugal, século XVIII

A partir da perspectiva analítica da cultura material investigaremos a valorização das aparências na sociedade portuguesa da primeira metade do século XVIII, examinando representações do vestir e do aparentar na literatura de cordel produzida por frei Lucas de Santa Catarina. Trata-se de observar alguns aspectos das relações entre aparências e comportamentos na construção de uma sátira que visava criticar a falta de correspondência entre ser e parecer, num contexto em que a mobilidade social despontava em diversos setores. Tais textos fornecem ao historiador um amplo quadro no qual indumentária e comportamentos são descritos de maneira imbricada nas rotinas cotidianas. A partir dessas descrições, observaremos os conjuntos de artefatos necessários ao cuidado da imagem a ser apresentada no meio social, analisando seus usos e a percepção deles transcritos nas fontes selecionadas. Assim, refletiremos sobre alguns dos embates acerca das vestimentas e das modas, que se fundamentavam na contestação da ascensão social e no esforço de conter um amplo processo de mudança que marcava a sociedade portuguesa do período.From the analytical perspective of material culture, this article will investigate the valuation of appearances in Portuguese society in the first half of the 18th century, through the examination of representations of clothing and appearance in the cordel literature produced by Frei Lucas de Santa Catarina. The objective is to observe some aspects of the relationships between appearances and behaviors in the construction of a satire that aimed to criticize the non-correspondence between being and appearing, in a context of emerging social mobility for several sectors. Such texts provide historians with a broad framework where clothing and behavior are described amid everyday routines. From these descriptions, we will observe the sets of artifacts necessary to care for the image to be presented in social environments, analyzing its uses and the perception of these transcripts in the selected sources. Thus, we will reflect on some of the clashes over clothing and fashion trends that were based on the challenge of social ascension and the effort to contain a broad process of change that marked the Portuguese society of the period