AIM The aim of this in vitro study was to evaluate the surface roughness and hardness of both unbleached and bleached (opalescence; 10% carbamide peroxide) human enamel brushed with water (without dentifrice), fluoride abrasive dentifrice (Colgate Total) and whitening dentifrice (Natural White). MATERIALS AND METHODS Human enamel samples were obtained from third molars and randomly divided in...

In the conclusion of his monumental paper on optimal inapproximability results, H̊astad [13]suggested that Fourier analysis of Dictator (Long Code) Tests does not seem universally appli-cable in the study of CSPs. His main open question was to determine if the technique couldresolve the approximability of satisfiable 3-bit constraint satisfaction problems. In particular,he as...

Type II conventional glass-ionomer cements (GIC) are restorative materials consisting of powder and liquid mixed to produce a plastic mass that subsequently sets to a rigid solid. The early GIC was marketed without the expired date, although this material has been currently marketed with the expired date, how stable the materials are not yet clear. The purpose of this study was to evaluate the ...

Nanoindentation testing is a technique that determines the mechanical properties of a material in the sub-micron scale. The test involves penetrating a sample material using an indenter, while the penetration depth and load are recorded so that the stiffness and hardness of the indented location can be subsequently calculated. The continuous stiffness measurement technique offers a tool to prob...

The aim of the work was to evaluate the influence of the temperature of investment healting on the tensile strength and Vickers hardness of CP Ti and Ti-6Al-4V alloy casting. Were obtained for the tensile strength test dumbbell rods that were invested in the Rematitan Plus investment and casting in the Discovery machine cast. Thirty specimens were obtained, fifteen to the CP Titanium and fiftee...

The study aimed at evaluating the depth of cure and knoop hardness of a microfine-hybrid composite resin that was photo-activated using different methods. A bipartite brass mold was filled with composite resin and photo-activation was performed using four methods: (1) Intermittent method using quartz tungsten halogen (QTH) light curing unit (LCU) (2) Continuous method (QTH) (3) Exponential meth...

Purpose: The mechanical strength of polymethyl methacrylate (PMMA) remains far from ideal for maintaining the longevity of denture. The purpose of this study was to evaluate the effect of Zirconium oxide (ZrO2) nanofillers powder with different concentration (1.5%, 3%, 5% and 7%) on the flexural strength, fracture toughness, and hardness of heat-polymerized acrylic resin. Materials and methods:...

Stainless steels stabilized with Ti or Nb are largely used in offshore and shipbuilding industries due to its excellent corrosion resistance. In this study, carbide stabilizers, Ti and Nb, were added to stainless steel 304 specimens with different concentrations(Ti: 0.26%, 0.71%, Nb: 0.29%, 0.46%, 0.71%), and their mechanical and electrochemical characteristics were evaluated. Micro-Vickers har...

The objective of this study was to investigate the effect of laser beam parameters on the mechanical and physical properties of cast commercially pure titanium. Dumbbell-shaped test specimens (ISO6871) were cast with ASTM grades 2 and 3 Ti. The cast surfaces were laser-treated with various laser emission parameters (current: 200, 220, and 240 A; spot diameter: 1.0, 1.6 mm; pulse duration: 10, 1...

This study determined the hardness and curing depth of a light-activated indirect composite polymerized with three laboratory light-polymerizing units for the purpose of comparing the curing performance of the three units. A light-activated composite material for indirect application (Vita Zeta) was polymerized with three light-polymerizing units equipped with the following light sources: 1) on...