Effects of aging procedures on the topographic surface, structural stability, and mechanical strength of a ZrO2-based dental ceramic

Objective. To determine the effects of different aging methods on the degradation and flexural strength of yttria-stabilized tetragonal zirconia (Y-TZP)Methods. Sixty disc-shaped specimens (0, 12 mm; thickness, 1.6 mm) of zirconia (Vita InCeram 2000 YZ Cubes, VITA Zahnfabrik) were prepared (ISO 6872) and randomly divided into five groups, according to the aging procedures (n=10): (C) control; (M) mechanical cycling (15,000,000 cycles/3.8 Hz/200N); (T) thermal cycling (6,000 cycles/5-55 degrees C/30 s); (TM) thermomechanical cycling (1,200,000 cycles/3.8 Hz/200N with temperature range from 5 C to 55 C for 60s each); (AUT) 12h in autoclave at 134 degrees C/2 bars; and (STO) storage in distilled water (37 degrees C/400 days). After the aging procedures, the monoclinic phase percentages were evaluated by X-ray diffraction (XRD), and topographic surface analysis was performed by 3D profilometry. The specimens were then subjected to biaxial flexure testing (1 mm/min, load 100 kgf, in water). The biaxial flexural strength data (MPa) were analyzed by 1-way ANOVA and Tukey's test (alpha = 0.05). The data for monoclinic phase percentage and profilometry (Ra) were analyzed by Kruskal-Wallis and Dunn's tests.Results. ANOVA revealed that flexural strength was affected by the aging procedures (p = 0.002). The M (781.6 MPa) and TM (771.3 MPa) groups presented lower values of flexural strength than did C (955 MPa), AUT (955.8 MPa), T (960.8 MPa) and STO (910.4 MPa). The monoclinic phase percentage was significantly higher only for STO (12.22%) and AUT (29.97%) when compared with that of the control group (Kruskal-Wallis test, p = 0.004). In addition, the surface roughnesses were similar among the groups (p = 0.165).Signcance. Water storage for 400 days and autoclave aging procedures induced higher phase transformation from tetragonal to monoclinic; however, they did not affect the flexural strength of Y-TZP ceramic, which decreased only after mechanical and thermomechanical cycling. (C) 2014 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Cardiac Energy Metabolism and Oxidative Stress Biomarkers in Diabetic Rat Treated with Resveratrol

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

Influence of nanoparticles on color stability, microhardness, and flexural strength of acrylic resins specific for ocular prosthesis

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

Energy restriction and impact on indirect calorimetry and oxidative stress in cardiac tissue in rat

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Analysis of Lattice Size, Energy Density and Denaturation for a One-Dimensional DNA Model

There are several mechanical models to describe the DNA phenomenology. In this work the DNA denaturation is stu- died under thermodynamical and dynamical point of view using the well known Peyrard-Bishop model. The thermody-namics analysis using the transfer integral operator method is briefly reviewed. In particular, the lattice size is discussed and a conjecture about the minimum energy to denaturation is proposed. In terms of the dynamical aspects of the model, the equations of motion for the system are integrated and the results determine the energy density where the denatura- tion occurs. The behavior of the lattice near the phase transition is analyzed. The relation between the thermodynamical and dynamical results is discussed.

Impact of chemical agents for surface treatments on microhardness and flexural strength of root dentin

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Apparent protein and energy digestibility and amino acid availability of corn and co-products in extruded diets for nile tilapia, oreochromis niloticus

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Influence of thicknesses of smear layer on the transdentinal cytotoxicity and bond strength of a resin-modified glass-ionomer cement

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Short-term low-intensity blood flow restricted interval training improves both aerobic fitness and muscle strength

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Estimate of concrete block texture using image analysis

The texture of concrete blocks is very important and is often the decisive factor when choosing a product, particularly if the building specifications call for high-strength blocks allied to low-cost finish, in which case exposed blocks with a closer texture are often preferred. Furthermore, a closer texture, especially for exteriors, may be a vital factor in ensuring the building's durability. At present, however, there is no standard to quantify the texture of a structural block. Further, when studying masonry blocks compressive strength should never be overlooked. This article discusses a procedure to produce concrete block textures with and without the addition of lime, but still to achieve the required compressive strength. The method used in this study, to evaluate texture, proved to be simpler and cheaper than methods reported by other authors in the literature. The addition of small quantities of lime proved beneficial for both texture and compressive strength. Increasing the amount of lime further, however, only improved texture.

Application of UTHSCSA-Image ToolTM to estimate concrete texture

The texture of concrete blocks is very important and is often the decisive factor when choosing a product, particularly if the building specifications does not dispense with the high resistance of the blocks, but has the purpose of reducing costs with finishing, therefore preferring exposed blocks with a closer texture. Furthermore, a closer texture, especially for exteriors,may be the vital factor of the building's pathology.However, there is so far no standard to quantify the texture of a structural block. This article proposes to apply the freely available UTHSCSA-Image ToolTM program developed by the University of Texas Health Science Center at San Antonio to evaluate the texture of masonry blocks. One aspect that should never be overlooked when studying masonry blocks is compressive strength. Therefore, this work also gets the compressive strength of the blocks with and without the addition of lime. The addition of small quantities of lime proved beneficial for both texture and compressive strength. However, increasing the amount of lime proved to be feasible only to improve texture. © 2012 Taylor & Francis Group.

Avaliação de solubilidade e desintegração, alteração dimensional e resistência à compressão de cimentos endodônticos

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Análise das influências do branqueamento na retenção de caulim e nas propriedades do papel

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Investigação do potencial dos ensaios APULOT e pull-out para estimativa da resistência a compressão do concreto

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Propriedades físicas e mecânicas de um cimento de ionômero de vidro após a incorporação de nanopartículas de dióxido de titânio

Pós-graduação em Ciências Odontológicas - FOAR