β -Acetamido ketones are valuable building blocks for the preparation of β -amino ketones or β -amino alcohols such as the antibiotic nikkomycins [1] and neopolyoxines [2]. α-Acetamido ketones are obtained in the Dakin-West reaction [3] and β -acetamido ketones by the Iqbal route. In the latter, an aromatic aldehyde, an enolizable ketone and acetonitrile are condensed in the presence of acetyl ...

In this study, two types of porous zirconia and dense zirconia were used. The flexural strength of non-layered zirconia specimens and those of the layered zirconia specimens with veneering porcelain were examined. Furthermore, the shear bond strength of veneering porcelain to zirconia was examined. The flexural strength of the non-layered specimens was 1,220 MPa for dense zirconia and 220 to 30...

Nanosized sulfated zirconia with Brønsted acidic sites has been prepared by a simple calcination in the absence of any solvent. XRD patterns reveal that the sulfated zirconia mainly consists of tetragonal crystalline zirconia with average size of about 7 nm, which is further confirmed by TEM images. N2 adsorption data show that the nanosized sulfated zirconia has high surface area (165-193 m2/g...

The purpose of this study is to evaluate the fitting accuracy and fracture resistance of crowns using a hybrid zirconia frame made of both porous and dense zirconia. Commercial semi-sintered zirconia, sintered dense zirconia and sintered hybrid zirconia were used. Sintered zirconia was milled using the CAD/CAM system, and semi-sintered zirconia was milled and sintered to fabricate molar crown f...

During the past decade, zirconia-based ceramics have been successfully introduced into the clinic to fabricate fixed dental prostheses (FDPs), along with a dental computer-aided/computer-aided manufacturing (CAD/CAM) system. In this article (1) development of dental ceramics, (2) the current status of dental CAD/CAM systems, (3) CAD/CAM and zirconia restoration, (4) bond between zirconia and ve...

Veneer cracking or chipping is the major complication of the zirconia based restorations. Monolithic zirconia has been introduced to overcome this problem, as well as to use in patients with limited interocclusal space. Many research articles on monolithic zirconia crowns have been published in the last years. The aim of this review article was to present data about the wear, surface roughness,...

The aim of the study was to evaluate the core veneer bond strength of graded zirconia combinations and compared those to conventional zirconia combinations after thermal and mechanical tests. Conventional zirconia-veneer combinations and graded zirconia-veneer combinations were made into cylinders. Prior to shear bond testing, half of each group was subjected to thermal and mechanical cycling t...

This article presents a literature review on the resin bond to zirconia ceramic. Modern esthetic dentistry has highly recognized zirconia, among other ceramic materials. Biocompatibility of zirconia, chemical and dimensional stability, excellent mechanical properties, all together could guarantee optimal therapeutical results in complex prosthodontic reconstruction. On the other hand, low therm...

AIM The purpose of this in vitro study was to assess and compare the retention of zirconia copings luted with different luting agents onto zirconia and titanium abutments. MATERIALS AND METHODS Titanium and zirconia abutments were torqued at 35 N/cm onto implant analogs. The samples were divided into two groups: Group A consisted of four titanium abutments and 32 zirconia copings and Group B ...

OBJECTIVE The aims of this study were to compare the shear bond strength between orthodontic metal brackets and glazed zirconia using different types of primer before applying resin cement and to determine which primer was more effective. METHODS Zirconia blocks were milled and embedded in acrylic resin and randomly assigned to one of four groups: nonglazed zirconia with sandblasting and zirc...