Search results for "visual_art"
showing 10 items of 2987 documents
Microstructural, mechanical and tribological properties of suspension plasma sprayed YSZ/h-BN composite coating
2018
Abstract Brittleness, relative high friction coefficient and wear rate limit the applications of ceramic coatings as wear-resistant layers. However, because embedding additives with ceramic matrix has demonstrated to be an effective way to improve coating performances, different contents and size of h-BN were added into an YSZ suspension. Afterwards, the YSZ/h-BN composite coatings were manufactured by suspension plasma spray and their tribological analysis indicated that: i) the reduction of the friction coefficient and wear rate can be achieved by incorporating h-BN into YSZ coating. ii) finer h-BN particle is more helpful to enhance the tribological properties of the coating. iii) the op…
Effect of cavity preparation instruments (oscillating or rotating) on the composite-dentin interface in primary teeth.
2003
Abstract Objectives: To evaluate the effect of preparation of instruments on the interfacial integrity between cavity wall and composite restoration. Methods: Two class II slot preparations were done in 10 primary teeth either with SonicSys® or with a conventional bur. The cavities were filled using an adhesive system. One layer of a flowable composite and one layer of a condensable composite were applied. The specimens were analyzed by confocal laser scanning microscopy. Results: In the SonicSys® group the mean thickness of the hybrid layer was 6.12 (0.60) μm; in the control group it was 6.04 (0.63) μm. The difference was not statistically significant. Two fractures were observed in one to…
Impact behaviour of flax/epoxy composite plates
2015
This paper presents an experimental investigation of the impact behaviour of flax/epoxy composite plates submitted to low-velocity transverse impact. Low energy drop-weight impact tests have been performed on two types of quasi-isotropic flax/epoxy composites, rectangularly shaped with edges lengths of 142 mm × 94 mm and 2.85 mm thick. Residual properties have been assessed by compression after impact tests. A detailed description of damage development, especially the increase of the rear face crack with respect to the impact energy is given by the microscopic observation. The influence of impact damage on the residual strength is described. A loss of 15%–30% in compression resistance was n…
Dentin bonding agent with improved bond strength to dentin through incorporation of sepiolite nanoparticles.
2017
Background The study aims to investigate the effect of incorporation of sepiolite nanoparticles on the microtensile bond strength of an experimental dentin bonding to the human dentin. Material and methods The sepiolite nanoparticles were incorporated into an experimental methacrylate-based dentin bonding system in concentrations of 0.0, 0.2, 1.0, 2.0, and 5.0 weight percents. The specimens were then ultrasonicated to finely disperse the nanoparticles in the adhesive matrix. The coronal enamel of 30 intact human premolars was cut to expose dentin. Having etched, rinsed, and blot dried the experimental bonding agents were applied to dentin surface. Adper Single Bond was used as control group…
Effect of aluminum chloride hemostatic agent on microleakage of class V composite resin restorations bonded with all-in-one adhesive
2012
Objectives: Since hemostatic agents can induce changes on enamel and dentin surfaces and influence composite resin adhesion, the aim of the present study was to evaluate the effect of the aluminum chloride hemostatic agent on the gingival margin microleakage of class V (Cl V) composite resin restorations bonded with all-in-one adhesive. Study design: Cl V cavities were prepared on the buccal surfaces of 60 sound bovine permanent incisors. Gingival margins of the cavities were placed 1.5 mm apical to the cemento-enamel junction (CEJ). The teeth were randomly divided into two groups of 30. In group 1, the cavities were restored without the application of a hemostatic agent; in group 2, the ca…
Evaluating the shear bond strength of enamel and dentin with or without etching: a comparative study between dimethacrylate-based and silorane-based …
2015
Background: Silorane-based composites and their specific self-etch adhesive were introduced to conquest the polymerization shrinkage of methacrylate-based composites. It has been shown that additional etching of enamel and dentin can improve the bond strength of self-etch methacrylate-based adhesives but this claim is not apparent about silorane-based adhesives. Our objective was to compare the shear bond strength (SBS) of enamel and dentin between silorane-based adhesive resin and a methacrylate-based resin with or without additional etching. Material and Methods: 40 sound human premolars were prepared and divided into two groups: 1- Filtek P60 composite and Clearfil SE Bond adhesive; 2- F…
Bulk filling of Class II cavities with a dual-cure composite: Effect of curing mode and enamel etching on marginal adaptation.
2014
Objectives: This study attempted to find a simple adhesive restorative technique for class I and II cavities on posterior teeth. Study Design: The tested materials were a self-etching adhesive (Parabond, Coltene/Whaledent) and a dual-cure composite (Paracore, Coltene/Whaledent) used in bulk to restore the cavities. Class II MO cavities were performed and assigned to 4 groups depending on the orthophosphoric acid (H3PO4) conditioning of enamel and polymerization method used (chemical or dual). Specimens were subjected to quantitative marginal analysis before and after thermo-mechanical loading. Results: Higher percentages of marginal adaptation at the total margin length, both before and aft…
Shear bond strength of orthodontic metal brackets to aged composite using three primers
2017
Background This study aimed to assess the effect of surface preparation with sandblasting and diamond bur along with the use of three primers on shear bond strength (SBS) of metal brackets to aged composite. Material and methods In this in vitro, experimental study, 60 Filtek Z250 composite discs were fabricated (10×2mm), immersed in distilled water for 24 hours and subjected to 5000 thermal cycles. They were randomly divided into two groups (n=30) of sandblasting with aluminum oxide particles for 10 seconds and surface roughening with bur. Each group was randomly divided into three subgroups (n=10) for use of Transbond XT, Assure Plus and Composite Primer. Metal brackets were bonded and th…
Applicability Range of the One-Parameter Ply Plasticity Model for Prediction of the Nonlinear Response of Laminates
2005
A one-parameter lamina plasticity model is applied to predict the nonlinear deformation of an E-glass / epoxy cross-ply composite laminate under quasi-static uniaxial tensile loading at different angles to the material orthotropy axes. It is shown that the laminate theory yields accurate results within the plastic strain range covered in unidirectional continuous-fibre reinforced composite tests that are used to determine the plasticity model parameters.
Influence of cavity preparation technique (rotary vs. ultrasonic) on microleakage and marginal fit of six end-root filling materials
2010
Objectives: To evaluate in vitro the effect of cavity preparation with microburs and diamond-coated ultrasonic tips on the microleakage and marginal fit of six end-root filling materials. Study Design. The following materials were assessed: amalgam (Amalcap), zinc oxide eugenol (IRM), glass ionomer (Vitrebond), compomer (Cavalite), mineral particle aggregate (MTA) and composite (Clearfil). Cavity preparation was performed with microburs or diamond ultrasonic tips in single-root teeth. The seal was evaluated in two experiments: a microleakage assay on the passage of dye to the interface; and a scanning electron microscopy study and analysis of epoxy resin replicas, measuring the size of gaps…