Background. The color masking ability of a restoration plays a significant role in coveringa discolored substructure; however, 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 a...

BACKGROUND To evaluate the influence of thermal and mechanical fatigue on the shear bond strength of different all-ceramic cores and veneering porcelain interfaces. MATERIAL AND METHODS All-ceramic systems tested were lithium disilicate and zirconia veneered by layering technique. Sixty specimens (n=20) were subjected to shear bond strength. Ten of them were thermal and mechanical cycled. Fra...

Background: There is increased use of all-ceramic crowns in place of ceramo-metal crowns in restorative practices. The difference in properties of different ceramics will affect the final esthetics of the restoration, and we need to consider this, especially when restoring anterior teeth. This article compares and analyzes translucency levels of different zirconia-based ceramic CAD/CAM systems....

The thermochemlcal stablllty of fast oxygen ion conductlng yttria stabillzed blsmuthoxlde (YSB) r solld solutlons containing 22.0 32.5 mol% of yttrla was investigated. It was shown that In the temperature range between 650 740 C the stabilized cublc ~ -phase contalnlng less than 31.8 mol% of yttrla ls not stable durlng long term annealing treatments (>~500 hours). During annealing at 650 C a sl...

Crystal structure and compressibility of potassium azide was investigated by in-situ synchrotron powder X-ray diffraction in a diamond anvil cell at room temperature up to 37.7 GPa. In the bodycentered tetragonal (bct) phase, an anisotropic compressibility was observed with greater compressibility in the direction perpendicular to the plane containing N3 ions than directions within that plane. ...

OBJECTIVES Fracture strength is an important factor influencing the clinical long-term success of implant-supported prostheses especially in high stress situations like excessive crown height space (CHS). The purpose of this study was to compare the fracture strength of implant-supported fixed partial dentures (FPDs) with excessive crown height, fabricated from three different materials. MATE...

The aims of this study were to determine the fracture origins and crack paths in the porcelain of clinically failed bilayer ceramic restorations and to reveal the correlation between the porcelain failures and material properties. Three clinically failed crowns of each material (bilayer zirconia crowns, galvano-ceramic crowns, and porcelain-fused-to-metal crowns) were collected and underwent fa...

Zirconia ceramics have several advantages over other ceramic materials, due to the transformation toughening mechanisms operating in their microstructure that can give to components made out of them, very interesting mechanical properties. The research on the use of zirconia ceramics as biomaterials started about twenty years ago, and now zirconia (Y-YZP) is in clinical use in THR, but developm...

This paper presents a possibility to use Resonant Ultrasound Spectroscopy as nondestructive evaluation method for ceramic elements of prosthesis such as ceramic femoral heads. With this method can be emphasized the incorrect sintering of these elements as well as eventually cracks. If the number of resonance peaks is big enough, the elements of elasticity matrix can be determined, demonstrated ...

OBJECTIVE The aim of this study was to assess the surface of yttrium-stabilized tetragonal zirconia (Y-TZP) after surface treatment with lasers and airborne-particle abrasion. MATERIALS AND METHODS First, 77 samples of presintered zirconia blocks measuring 10 × 10 × 2 mm were made, sintered and polished. Then, they were randomly divided into 11 groups (n=7) and received surface treatments nam...