The aim of this study is to evaluate the flexural resistance of three types of restorative materials: compomer (Freedom), resin-modified glass-ionomer (Vitremer) and composite resin (Esthet-X), observing whether the application of bleaching agent can cause alterations of their flexural properties. Sixty samples were made using a 10 x 1 x 1 mm brass mold, and divided into three groups: G1- Freed...

This study evaluated the effect of water-bath and microwave post-polymerization treatments on the flexural strength and Vickers hardness of four autopolymerizing reline resins (Duraliner II-D, Kooliner-K, Tokuso Rebase Fast-TR and Ufi Gel Hard C-UGH) and one heat-polymerized acrylic resin (Lucitone 550-L), processed using two polymerization cycles (short cycle - 90 minutes at 73 degrees C and 1...

Introduction Fatigue is the structural damage that leads the components of a wind turbine to sudden brittle failure when it suffers cyclic loading [15]. As the size of wind turbines is growing, fatigue loads become more and more significant for the design of major structural components. Concerning fatigue in a wind turbine tower, the fore-aft tower foot bending moment is considered as the most ...

To evaluate a Ni-43.5wt%Ti alloy as a new alloy for cast clasp, the fatigue properties of its castings were examined and compared with those of Co-Cr and Type IV Au alloys castings. The Ni-Ti alloy was cast into a phosphate-bonded investment mold using an argon-arc melting and pressure casting machine. The Ni-Ti alloy castings showed superelasticity in bending tests. Fatigue tests were carried ...

The purpose of this study was to analyze the type and frequency of defects in nickel-titanium rotary endodontic files after routine clinical use, and to draw conclusions regarding the reasons for failure. All of the files (total: 378, Quantec Series 2000) discarded after normal use from a specialist endodontic practice over 6 months were analyzed. Almost 50% of the files showed some visible def...

In a Z-core sandwich panel, the shear stiffness of the sandwich panel in the weak direction which is perpendicular to the placement of the Z-cores is much smaller than the bending stiffness because the hollow section between the two facing plates cannot sustain shear action. Because of this fact, the shear deformation of a Z-core sandwich panel under bending in the weak direction cannot be igno...

CaO-P(2)O(5) glasses with additions of MgO and CaF(2) were used as a sintering aid of hydroxyapatite, and glass-reinforced hydroxyapatite composites obtained. Glasses promoted significant changes in the microstructure of the composites, namely with the formation of tricalcium phosphate secondary phases, beta and alpha-TCP. Quantitative phase analysis was performed by the Rietveld method using G...

AIM The purpose of this study was to evaluate and compare the flexural strength of commercially available acrylic (trevalone) and modified polymethylmethacrylate (PMMA). MATERIALS AND METHODS Four groups were tested; Group 1- control group regular MMA, group 2-2% methacrylic acid, 88% MMA, group 3-16% methacrylic acid, 84% MMA group 4- 20% methacrylic acid, 80% MMA 15 resin specimens of each ...

Our primary objective was to validate the Bone Strength Index for compression (BSIC) by determining the amount of variance in failure load and stiffness that was explained by BSIC and bone properties at two distal sites in human cadaveric tibiae when tested in axial compression. Our secondary objective was to assess the variance in failure moment and flexural rigidity that was explained by bone...

Motivated by recent free-standing graphene experiments, we show how thermal fluctuations affect the mechanical properties of microscopically thin solid ribbons, which can be many thousand times wider than their atomic thickness. A renormalization group analysis of flexural phonons reveals that elongated ribbons behave like highly anisotropic polymers, where the two dimensional nature of ribbons...