This study evaluated the masking ability of two opaques applied in different thicknesses. Eighty NiCr metal discs 16 mm in diameter and 1.0 mm thick were prepared. The disks were divided into 8 groups (n = 10). Ceramic opaque in paste (groups 1 to 4) or powder (groups 5 to 8) presentations were applied. They were machined with aluminum oxide burs to the following thicknesses: G1 and G5 = 0.10 m...

OBJECTIVE Evaluate the immediate and cumulative optical whitening efficacy of a blue covarine toothpaste. MATERIALS AND METHODS 180 bovine tooth specimens with similar shade (ΔE < 3.5) were staining of different beverage: black tea(BT), green tea (GT), red wine (RW), orange soda (OS), and brazilian açai juice (AJ), and then submitted to tooth brushing with a blue covarine toothpaste (Op) or a...

The slip behavior of simple fluids over atomically smooth surfaces was investigated in a wide range of wall-fluid interaction (WFI) energies at low shear rates using non-equilibrium molecular dynamics simulations. The relationship between slip and WFI shows two regimes (the strong-WFI and weak-WFI regimes): as WFI decreases, the slip length increases in the strong-WFI regime and decreases in th...

OBJECTIVES The aim of this study was to evaluate tooth discoloration induced by contact with various calcium silicate-based pulp capping materials in the presence or absence of blood in vitro. MATERIALS AND METHODS Eighty bovine samples were divided into six experimental groups and two control groups according to the type of material used (ProRoot [PR], Endocem [EC], or EndocemZr [ECZ]) and t...

OBJECTIVE To study the effect of three energy drinks on the color stability of nanofilled composite resins after different periods of aging time. MATERIALS AND METHODS Composite resin disks, 6 mm diameter, 3 mm thickness were prepared from Filtec Z350 XT, Tetric EvoCeram, and Filtec Z250 XT. Specimens from each material were tested after aging with Red Bull, Bison and Power Horse energy drink...

OBJECTIVES Polyamide-12 (PA) is a flexible material suited for denture bases and clasping. This study investigated its potential aging effects with a focus on surface roughness, color stability, and elasticity. METHODS PA specimens (Valplast) of 40×10×2 mm and equally measuring PMMA specimens (Palapress) as control were fabricated. Color changes after storage in air, water, coffee, and red wi...

background. the color masking ability of a restoration plays a significant role in coveringa discolored substructure; how-ever, this optical property of zirconia ceramics has not been clearly determined yet. the aim of this in vitro study was to evaluate the color masking ability of a zirconia ceramic on substrates with different values. methods. ten zirconia disk specimens,0.5 mm in thickness ...

Eigenvalues and eigenfunctions of the QCD Dirac operator are studied for gauge field configurations given by a liquid of instantons. We find that for energy differences δE below an energy scale Ec the eigenvalue correlations are given by Random Matrix Theories with the chiral symmetries of the QCD partition function. For eigenvalues near zero this energy scale shows a very weak volume dependenc...

OBJECTIVE The aim of this study was to evaluate the effects of staining solutions on the color stability and roughness of different provisional resin material. MATERIAL AND METHODS Three different materials were tested (two polymethylmethacrylate and one bis-acryl composite resins) in cola and coffee and for 1 and 4 weeks. 240 specimens were used - half of them polished and other half not. Co...

This perspective describes research, carried out in the authors' labs over the past forty years, aimed at understanding, predicting, and measuring the singlet-triplet energy differences (ΔE(ST)) in diradicals. A theory for qualitatively predicting the ground states of diradicals and the use of Negative Ion Photoelectron Spectroscopy (NIPES) for measuring ΔE(ST) are described. The application of...