Pre-sintered Y-TZP sandblasting: effect on surface roughness, phase transformation, and Y-TZP/veneer bond strength

Abstract Sandblasting is a common method to try to improve the Y-TZP/veneer bond strength of dental prostheses, however, it may put stress on zirconia surfaces and could accelerate the t→m phase transformation. Y-TZP sandblasting before sintering could be an alternative to improve surface roughness and bonding strength of veneering ceramic. Objectives. The aim of this study was to analyze the effect of Y-TZP pre-sintering sandblasting on surface roughness, phase transformation, and the Y-TZP/veneer shear bond strength. Material and Methods. The Y-TZP specimen surface underwent sandblasting with aluminum oxide (50 μm) pre-sintering (Z-PRE) and post-sintering (Z-POS). Z-CTR was not subjected to surface treatment. After ceramic veneer application, the specimens were subjected to shear bond testing. Surface roughness was analyzed by confocal microscopy. Y-TZP monoclinic and tetragonal phases were evaluated by micro-Raman spectroscopy. Shear bond strength and surface roughness data were analyzed by One-way ANOVA and Tukey tests (α=0.05). Differences in the wave numbers and the broadening bands of the Raman spectra were compared among groups. Results. Z-POS (9.73±5.36 MPa) and Z-PRE (7.94±2.52 MPa) showed the highest bond strength, significantly higher than that of Z-CTR (5.54±2.14 MPa). The Ra of Z-PRE (1.59±0.23 µm) was much greater and significantly different from that of Z-CTR (0.29±0.05 µm) and Z-POS (0.77±0.13 µm). All groups showed bands typical of the tetragonal (T) and monoclinic (M) phases. Y-TZP sandblasting before sintering resulted in rougher surfaces but did not increase the shear bond strength compared to post-sintering and increased surface defects. Conclusions. Surface treatment with Al3O2, regardless of the moment and application, improves the results of Y-TZP/veneer bonding and is not a specific cause of t→m transformation.

Influence of the tilt angle of Percutaneous Aortic Prosthesis on Velocity and Shear Stress Fields / Influência do Ângulo de Inclinação da Prótese Percutânea Aórtica no Campo de Velocidade e Estresse de Cisalhamento

Abstract Background: Due to the nature of the percutaneous prosthesis deployment process, a variation in its final position is expected. Prosthetic valve placement will define the spatial location of its effective orifice in relation to the aortic annulus. The blood flow pattern in the ascending aorta is related to the aortic remodeling process, and depends on the spatial location of the effective orifice. The hemodynamic effect of small variations in the angle of inclination of the effective orifice has not been studied in detail. Objective: To implement an in vitro simulation to characterize the hydrodynamic blood flow pattern associated with small variations in the effective orifice inclination. Methods: A three-dimensional aortic phantom was constructed, reproducing the anatomy of one patient submitted to percutaneous aortic valve implantation. Flow analysis was performed by use of the Particle Image Velocimetry technique. The flow pattern in the ascending aorta was characterized for six flow rate levels. In addition, six angles of inclination of the effective orifice were assessed. Results: The effective orifice at the -4° and -2° angles directed the main flow towards the anterior wall of the aortic model, inducing asymmetric and high shear stress in that region. However, the effective orifice at the +3° and +5° angles mimics the physiological pattern, centralizing the main flow and promoting a symmetric distribution of shear stress. Conclusion: The measurements performed suggest that small changes in the angle of inclination of the percutaneous prosthesis aid in the generation of a physiological hemodynamic pattern, and can contribute to reduce aortic remodeling.

Resumo Fundamento: Devido à natureza do processo de liberação da prótese percutânea, é esperada uma variabilidade do posicionamento final da válvula. A localização da prótese irá definir a posição espacial do seu orifício efetivo em relação ao ânulo aórtico. O padrão do fluxo sanguíneo em aorta ascendente está relacionado ao processo de remodelamento aórtico, além de ser dependente da disposição espacial do orifício efetivo. O efeito hemodinâmico de pequenas variações na angulação do orifício efetivo ainda não foi estudado em detalhes. Objetivo: O objetivo do presente trabalho foi implementar uma simulação in vitro do fluxo sanguíneo para caracterização do padrão hidrodinâmico, associado a pequenas variações na inclinação do orifício efetivo. Métodos: Para esse fim, foi construído um fantoma aórtico tridimensional, que reproduziu a anatomia de um paciente submetido ao implante valvar percutâneo. A análise de fluxo foi realizada através da técnica de Velocimetria por Imagens de Partícula. O padrão de escoamento em aorta ascendente foi caracterizado para seis níveis de vazão de fluxo. Além disso, foram estudados seis inclinações do orifício efetivo. Resultados: O estudo demonstrou que o orifício efetivo nos ângulos -4° e -2° direcionaram o fluxo principal para a parede anterior do modelo aórtico, induzindo um cisalhamento assimétrico e elevado nessa região. Por outro lado, os ângulos +3° e +5° mimetizam o padrão fisiológico, centralizando o fluxo principal e promovendo uma distribuição simétrica do cisalhamento. Conclusão: As medições realizadas sugerem que pequenas alterações angulares na prótese percutânea auxiliam na geração de um padrão hemodinâmico fisiológico, podendo contribuir para menor remodelamento aórtico.

Effects of disturbed blood flow during exercise on endothelial function: a time course analysis

This study aimed to examine the time course of endothelial function after a single handgrip exercise session combined with blood flow restriction in healthy young men. Nine participants (28±5.8 years) completed a single session of bilateral dynamic handgrip exercise (20 min with 60% of the maximum voluntary contraction). To induce blood flow restriction, a cuff was placed 2 cm below the antecubital fossa in the experimental arm. This cuff was inflated to 80 mmHg before initiation of exercise and maintained through the duration of the protocol. The experimental arm and control arm were randomly selected for all subjects. Brachial artery flow-mediated dilation (FMD) and blood flow velocity profiles were assessed using Doppler ultrasonography before initiation of the exercise, and at 15 and 60 min after its cessation. Blood flow velocity profiles were also assessed during exercise. There was a significant increase in FMD 15 min after exercise in the control arm compared with before exercise (64.09%±16.59%, P=0.001), but there was no change in the experimental arm (-12.48%±12.64%, P=0.252). FMD values at 15 min post-exercise were significantly higher for the control arm in comparison to the experimental arm (P=0.004). FMD returned to near baseline values at 60 min after exercise, with no significant difference between arms (P=0.424). A single handgrip exercise bout provoked an acute increase in FMD 15 min after exercise, returning to near baseline values at 60 min. This response was blunted by the addition of an inflated pneumatic cuff to the exercising arm.

In vitro evaluation of shear bond strength of materials used in bonding 3x3 lingual retainer / Evaluación in vitro de la resistencia al cizallamiento de los materiales utilizados en la adhesión del retenedor lingual 3x3

The aim of the present study was to evaluate which material and technique were the best for bonding 3x3 lingual retainer. One hundred and five bovine mandibular incisors were used, to which contention bars with a standardized size of 7 mm were bonded to the lingual surface. Initially all teeth received prophylaxis with pumice stone and water. After this they were randomly divided into seven groups, denominated and characterized as follows: Group (1) bars bonded with Transbond XT in accordance with the manufacturer's instructions; (2) Tooth surface etching with self-etching agent Transbond (SEPT) followed by bonding with Transbond XT; (3) Bonding with Transbond Plus Color Change (TPCC) without adhesive; (4) Bonding with TPCC + SEPT; (5) Bonding with restorative composite Z100 + adhesive Prime Bond, (6) Z100 without adhesive and (7) Z100 + SEPT. Before bonding in Groups 1, 3, 5 and 6 the lingual surface was etched with 37 percent phosphoric acid for 20 seconds, followed by washing and drying. After bonding the mechanical tests were performed in a Universal mechanical test machine. The values obtained were submitted to the analysis of variance (ANOVA) and afterwards to the Tukey test (p<0.05). We observed absence of statistical differences among Groups 1, 2, 5 and 7 and among Groups 3, 4, 5 and 6 (p<0.05). Group 1 presented the highest bond strength value and Group 6 the lowest. It could be concluded that where bonding of lingual retainer is concerned; the best material to use is Transbond XT irrespective of the etching method, followed by composite Z100 etched with SEPT.

El objetivo fue evaluar cuáles materiales y técnicas eran mejores para la adhesión del retenedor lingual 3x3. Se utilizaron 105 incisivos mandibulares bovinos, a los que se adhirieron barras de contención con un tamaño estándar de 7 mm en la superficie lingual . Inicialmente todos los dientes recibieron profilaxis con piedra pómez y agua. Luego, se dividieron aleatoriamente en siete grupos, denominados y caracterizados como: Grupo (1) con barras unidas con Transbond XT de acuerdo con las instrucciones del fabricante , (2) Con la superficie del diente grabada con el agente de auto- grabado Transbond (SEPT), seguido por la adhesión con Transbond XT, (3) Adhesión con Transbond Plus Color Change (TPCC ) sin adhesivo, (4) Adhesión con TPCC + SEPT, (5) Adhesión con la resina restauradora Z100 + adhesivo Prime Bond, (6) Adhesión con Z100 sin adhesivo y (7) Z100 + SEPT. Previo a la adhesión en los Grupos 1, 3, 5 y 6 la superficie lingual fue grabada con ácido fosfórico al 37 por ciento durante 20 segundos, lavado y secado. Se realizaron los ensayos con una máquina de ensayo mecánico universal. Los valores obtenidos fueron sometidos al análisis de varianza (ANOVA ) y a la prueba de Tukey ( p < 0,05). No hubo diferencias estadísticas entre los grupos 1, 2, 5 y 7 y entre los Grupos 3, 4, 5 y 6 (p < 0,05 ). El grupo 1 presentó el mayor valor de resistencia de adhesión y el Grupo 6 el menor. Se podría concluir que cuando se trata de la adhesión de un retenedor lingual, el mejor material para usar es Transbond XT independiente del método de grabado, seguido de la resina Z100 grabada con SEPT.

Lesão de Morel-Lavallée no joelho: relato de caso / Morel-Lavallée lesion in the knee: a case report

A lesão de Morel-Lavallée é uma lesão em cisalhamento que ocorre entre o tecido celular subcutâneo e a fáscia profunda. Caracteriza-se pela formação de uma coleção que, originalmente descrita na coxa, vem sendo observada em outros locais. Os autores relatam o caso de paciente com Morel-Lavallée no joelho e descrevem as principais características desta lesão.

Morel-Lavallée lesion is a degloving injury of the interface between the subcutaneous fat and the underlying fascia. This lesion is characterized by the development of a fluid collection that, although originally described in the thigh, it has also been described in other anatomical sites. The authors report the case of a patient with Morel-Lavallée lesion in the knee after trauma and describe the main characteristics of the lesion.

Effect of temperature on shear bond strength of different dentin bonding system

Manufacturers currently recommend storage of adhesive materials at room temperatures, the historical practice of using refrigerated storage to extend shelf life is still used by many dentists. To determine The effect of temperature on the shear bond strength of bonding systems to dentin. Resin -based composite cylinders were bonded to dentin on the ground occlusal surfaces of 90 extracted human molars using three deferent dentin bonding systems at [4, 22,29] °C. The results were interpreted multiple range [Dunkin] test. Single bond demonstrated significantly higher shear bond strengths at 23°C than all other groups, at both. 4.0°C. and 29°C Scotch bond and and Prompt L-pop had lower shear bond strengths, but the differences were insignificant in magnitude. The Storage time was not affecting the shear bond strength