This paper investigates axial compression process of multi-layered tubes with circular cross-section under the axial loading in the quasi-static condition using experimental method. Some specimens are prepared in seven different groups, namely; empty carbon/epoxy composite tubes, solid carbon/epoxy composite rods, empty copper tubes, composite tubes with silicon sealant filler, concentrically s...

In this study, aluminum (Al) matrix reinforced with micro-particles (30 µm) and nano-particles (50 nm) boron carbide (B4C) were used to prepare Al-2.5%wt., B4C nano-composite and micro-composite, respectively, using mechanical alloying method. The mixed powders were mechanically milled at 5, 10, 15 and 20 hrs. The XRD results indicated that the crystallite sizes of both the micro-composite and ...

conclusions the most common cause of restoration replacement in patients referred to the babol university of dentistry during years 2013 and 2014 was secondary caries that were found in class ii restorations. patients and methods age, sex, type of occlusion, dmf, existing parafunction, type of tooth, class and reason of composite restoration replacement was recorded for patients who had referre...

polymerization contraction may produce defects in the composite - tooth bond. this may lead to bond failure and microleakage. the aim of this study was to reduce microleakage of posterior composites using different methods. 45 molar and premolars extracted teeth were choosen. the cavities were randomly assigned into 5 groups of 9. box-shaped cavities were prepared on each side of proximal surfa...

statement of the problem: the bond strength of composites with different adhesive systems with dentin is an important factor in long term durability of composite restorations. the effect of titanium tetrafluoride (tif4) as anti caries agent and sodium hypochlorite (naocl) as disinfectant on the shear bond of nanofilled and silorane based composite resins have not been investigated in previous s...

abstract: introduction: ditching and marginal defects of amalgam restorations can cause microleakage, recurrent carries, pulp hypersensitivity and finally loss of the tooth. the complete replacement of large restoration is time consuming, difficult and may potentially damage the pulp. therefore in cases were there is no sings of recurrent caries, composite repair can be chosen as an alternative...

because of inhomogeneity and anisotropy of composite materials, defining a unique fatigue criterion to be suitable for different loading conditions is much more difficult in comparison with traditional materials. for this reason many tests on evaluating the damages such as crack density, stiffness reduction and residual strength are used by various researchers to monitor the fatigue process. in...

background and aims. effect of surface treatments on repair bond strength of aged composite resins might be different due to their dissimilar fillers. the aim was to evaluate the effect of different surface treatments on repair micro-shear bond strength (µsbs) of silica- (spectrum tph) and zirconia-filled (filtek z250) composite resins. materials and methods. twenty-seven composite resin blocks...

objective: selection of an appropriate shade of composite is critical in achieving an esthetic restoration. different systems are used to assess and describe color parameters. this study aimed to assess the effect of color and thickness of filtek supreme (fs) and premise (p) composite resins on correction of tooth discoloration.   methods: in this in vitro experimental study, 10 anterior teeth ...