The synthesis of some thio-oxocrown ether ligands, B1 (1,4-dithio-12-crown-4), B2 (1,7-dithio-12-crown-4), B3 (1,7-dithio-15-Crown-5), B4 (1,7-dithio-18-crown-6), B5 (1,10-dithio-18-crown-6), B6 (1,10-dithio-21-crown-7), under mild conditions, were reported. The ligands were characterized by FT-IR, H NMR and GC-MS spectroscopy. The formation of 1:1 ligand complexes with a variety of metal salts...

Supercritical fluid CO 2 is an alternative solvent for extraction of metals. The solubility parameter of supercritical CO 2 varies with density resembling that of liquid hexane at moderate pressures in the supercritical region to those of chlorinated solvents at very high pressures. By changing density of supercritical CO 2 , the solvation environment of a metal chelate system can vary continuo...

The purpose of this study was to compare full metal crowns with two different types of veneering material - ceramics and polymer after a two-year period in a function. The aim was to evaluate the changes of occlusal relief, marginal adaptation, break of material, changes of shape and color and gingival status. One hundred and two crowns were examined in 34 patients immediately after cementation...

Olefin metathesis reactions of carbene-stabilized ruthenium nanoparticles were exploited for the incorporation of multiple functional moieties onto the nanoparticle surface. When the nanoparticles were cofunctionalized with 4-vinylbenzo-18-crown-6 and 1-vinylpyrene, the resulting particles exhibited fluorescence characteristics that were consistent with dimeric pyrene with a conjugated chemical...

Metal ceramic restorations have been implicated for the discoloration in area of labiogingivalmargin. Attempts to rectify this, by altering the design of metal frameworkswill lead to decrease in fracture strength atmargin. This in vitro study compared the fracture strength at margins of metal ceramic crowns cemented to metal tooth analogs. Crowns evaluated with different marginal configurations...

Novel di-ionizable p-tert-butylcalix[4]arene-1,2-crown-3 ligands in cone and 1,2-alternate conformations were prepared as potential metal ion extractants. Selective bridging of proximal hydroxyl groups of the calix[4]arene platform by a crown-3 polyether unit was achieved under Mitsunobu reaction conditions. In addition to the carboxylic acid group, the acidity tunable N-(X)sulfonyl oxyacetamid...

The gap between a metal crown and an abutment tooth often leads to troubles such as secondary caries, pulpitis, periodontitis and so on. We expected that newly developed adhesive resins which adhere both dental alloy and tooth structure can minimize such troubles if they were used as setting materials of prosthetics. In this study, the degree of marginal leakage of adhesive resins was compared ...

The preformed metal crown was first introduced in 1950, made of stainless steel it was referred to by an acronym of SSC. However soon the metal used was changed to nickel-chromium and these days it is best referred to as a preformed metal crown (PMC). I first encountered them in 1965 as a travelling extern in paedodontics in the backwoods of British Columbia (Canada). Not having been taught the...

This case report describes the management of an oblique crown-root fracture of maxillary left lateral incisor. After removal of the fractured fragment, endodontic treatment, the remaining tooth was provisionally restored. The tooth was then orthodontically extruded by 3 mm to raise the defect supraginigivally. Periondonal fibres were cut with a surgical blade. A metallic screw type post was ins...