Effect of thermal cycling and disinfection on colour stability of denture base acrylic resin

Objectives: The purpose of this study was to investigate the effect of thermal cycling and disinfection on the colour change of denture base acrylic resin. Materials and Methods: Four different brands of acrylic resins were evaluated (Onda Cryl, QC 20, Classico and Lucitone). All brands were divided into four groups (n=7) determined according to the disinfection procedure (microwave, Efferdent, 4% chlorhexidine or 1% hypochlorite). The treatments were conducted three times a week for 60days. All specimens were thermal cycled between 5 and 55°C with 30-s dwell times for 1000 cycles before and after disinfection. The specimens' colour was measured with a spectrophotometer using the CIE L*a*b* system. The evaluations were conducted at baseline (B), after first thermal cycling (T 1), after disinfection (D) and after second thermal cycling (T 2). Colour differences (ΔE) were calculated between T 1 and B (T 1B), D and B (DB), and T 2 and B (T 2B) time-points. Results: The samples submitted to disinfection by microwave and Efferdent exhibited the highest values of colour change. There were significant differences on colour change between the time-points, except for the Lucitone acrylic resin. Conclusions: The thermal cycling and disinfection procedures significantly affected the colour stability of the samples. However, all values obtained for the acrylic resins are within acceptable clinical parameters. © 2012 The Gerodontology Society and John Wiley & Sons A/S.

Effect of thermal cycling and disinfection on microhardness of acrylic resin denture base

The purpose of this study was to investigate the effect of thermal cycling and disinfection on the microhardness of acrylic resins denture base. Four different brands of acrylic resins were evaluated: Onda Cryl, QC 20, Classico and Lucitone. Each brand of acrylic resin was divided into four groups (n = 7) according to the disinfection method (microwave, Efferdent, 4% chlorhexidine and 1% hypochlorite). Samples were disinfected during 60 days. Before and after disinfection, samples were thermal cycled between 5-55 °C with 30-s dwell times for 1000 cycles. The microhardness was measured using a microhardener, at baseline (B), after first thermal cycling (T1), after disinfection (D) and after second thermal cycling (T2). The microhardness values of all groups reduced over time. QC-20 acrylic resin exhibited the lowest microhardness values. At B and T1 periods, the acrylic resins exhibited statistically greater microhardness values when compared to D and T2 periods. It can be concluded that the microhardness values of the acrylic resins denture base were affected by the thermal cycling and disinfection procedures. However, all microhardness values obtained herein are within acceptable clinical limits for the acrylic resins. © 2013 Informa UK Ltd.

Influence of visual feedback sampling on obstacle crossing behavior in people with Parkinson's disease

The purpose of the current study was to investigate the role of visual information on gait control in people with Parkinson's disease as they crossed over obstacles. Twelve healthy individuals, and 12 patients with mild to moderate Parkinson's disease, walked at their preferred speeds along a walkway and stepped over obstacles of varying heights (ankle height or half-knee height), under three visual sampling conditions: dynamic (normal lighting), static (static visual samples, similar to stroboscopic lighting), and voluntary visual sampling. Subjects wore liquid crystal glasses for visual manipulation. In the static visual sampling condition only, the patients with Parkinson's disease made contact with the obstacle more often than did the control subjects. In the successful trials, the patients increased their crossing step width in the static visual sampling condition as compared to the dynamic and voluntary visual sampling conditions; the control group maintained the same step width for all visual sampling conditions. The patients showed lower horizontal mean velocity values during obstacle crossing than did the controls. The patients with Parkinson's disease were more dependent on optic flow information for successful task and postural stability than were the control subjects. Bradykinesia influenced obstacle crossing in the patients with Parkinson's disease. © 2013 Elsevier B.V.

Plasma-polymerized acetylene nanofilms modified by nitrogen ion implantation

Thin films were prepared by plasma enhanced chemical vapour deposition (PECVD) from a mixture of acetylene and argon, and post deposition-treated by plasma immersion ion implantation (PIII). The effect of PIII on the nanofilms properties was evaluated as a function of treatment time. The average thickness and roughness were diminished upon PIII. On the other hand, hardness (0.7-3.9 GPa) and elastic modulus (29-54 GPa) increased upon 60 min of ion bombardment. Such results are ascribed mainly to the densification of the film structure caused by the increment in the crosslinking degree with increasing the energy deposited in the films. Wettability of the samples, investigated by contact angle measurements, was reduced (from 64 to 21°) right after PIII. This result, attributed to the introduction of polar groups in the film structure, was not preserved as the sample was aged in atmosphere. After aging, contact angles were larger than 70° but still smaller than 90°. Although the wettability has decreased with aging, the hydrophilic character of the samples was preserved. For certain treatment times, nitrogen PIII turned the plasma-polymerized acetylene films smoother, denser, mechanically and tribologicaly more resistant than the as-deposited material. © 2013 Elsevier B.V.

Sistema de gerenciamento automático de reatores eletrônicos com ajuste do nível de luminosidade para múltiplas lâmpadas fluorescentes

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Estudo experimental do escoamento em cavidades retangulares: padrões de escoamento e instabilidades hidrodinâmicas na camada cisalhante

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Os Olhos no outro: estudo da sensibilidade na imagem fotográfica de pessoas de diferentes culturas

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Estudo de caso do setor de tecelagem de uma indústria de fiação de seda, abordando pontos da ergonometria

Pós-graduação em Design - FAAC

Comparação entre a percepção e a normatização sobre a iluminação em ambientes ocupacionais: estudo de caso em uma empresa florestal

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Estudo das variáveis do conforto térmico e luminoso em ambientes escolares

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Análise ergonômica em laboratórios de informática nas instituições públicas educacionais de ensino fundamental de Bauru

Pós-graduação em Design - FAAC

Avaliação do programa “luz para todos”, implantado na cooperativa de eletrificação rural de Itaí, Paranapanema e Avaré - Ceripa

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Avaliação, modificação e validação de metodologia para estudo de estabilidade de hidroquinona em creme

Pós-graduação em Ciências Farmacêuticas - FCFAR

Dinâmica da paisagem na microbacia hidrográfica do rio Mojuí, oeste do estado do Pará

Pós-graduação em Agronomia (Irrigação e Drenagem) - FCA

Caracterização metalográfica de um aço de fases complexas (CP)

Pós-graduação em Engenharia Mecânica - FEG