This case report describes the management of an oblique crown-root fracture of maxillary left central 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...

Patients with tooth grinding habits may tend to wear through the occlusal surfaces of stainless steel crowns. A technique is described which prevents this problem by increasing metal occlusal surface thickness of the crown.

Extending to transition metals, the class of compounds known as inverse crown ethers, two mixed alkali metal-manganese(II) amide ring compounds with oxo cores have been synthesised and crystallographically characterised, together with an oxo-free alkyl-amido precursor.

Understanding the interaction of ions with organic receptors in confined space is fundamental importance and could advance nanoelectronics sensor design. In this work, metal ion complexation conformationally varied thiacalix[4]monocrowns bearing lower-rim hydroxy (type I), dodecyloxy II), or methoxy III) fragments was evaluated. At liquid–liquid interface, alkylated thiacalixcrowns-5(6) selecti...

The extraction-separation of alkali, alkaline earth, and rare earth metal ions could be improved by using macrocyclic ligands as ion size selective masking reagents. By adding a macrocyclic ligand to the aqueous phase of a conventional chelate extraction system, the extraction of metal ions with larger ionic radii was shifted to a higher pH region. Consequently, the separation among the metal i...

The ability of macroheterocyclic compounds to complex with ionic species has led to the synthesis and investigation of many multidentate macroheterocyclic species . The most stable complexes are formed between macrocyclic polyetheral ligands (crown ethers) with alkali or alkaline earth metal iona. There is an excellent correlation of the stability of these complexes with the size of the cation ...

The feasibility of fabricating copper-sensitive chemically modified electrodes (CMEs) for trace analysis in aqueous and in 40% (v/v) ethanol-water media was investigated. Carbon paste electrodes modified with crown ethers were constructed by mixing the crown ethers into a graphite powder-paraffin oil matrix. The electrodes so formed were able to bind Cu(II) ions chemically and gave better volta...

Novel 4-acyl-5-pyrazolones having aza-15-crown-5 (HPMP-A15C5) and aza-18-crown-6 (HPMP-A18C6) moieties as an intramolecular synergist have been synthesized by simple coupling reactions between 1-phenyl-3-methyl-4-chloroacetyl-5-pyrazolone and the corresponding azacrown ethers. The solvent extraction of the divalent metal ions (Mn(2+), Co(2+), Ni(2+), Cu(2+), Zn(2+), Cd(2+) and Pb(2+)) were exam...

PURPOSE One of the most important factors in evaluating the quality of fixed dental prostheses (FDPs) is their gap. The purpose of this study was to compare the marginal and internal gap of two different metal-ceramic crowns, casting and selective laser sintering (SLS), before and after porcelain firing. Furthermore, this study evaluated whether metal-ceramic crowns made using the SLS have the ...

We describe the synthesis of a cyapho(dicyano)methanide salt, [K(18-crown-6)][C(CN)2(CP)], from reaction [Na(18-crown-6)][PH2] (18-crown-6=1,4,7,10,13,16-hexaoxacyclooctadecane) with 1,1-diethoxy-2,2-dicyanoethylene (EtO)2C=C(CN)2. The proceeds through Michael addition-elimination pathway to afford [Na(18-crown-6)][HP{C(OEt)=C(CN)2}]. Addition strong, non-nucleophilic base (KHMDS) this intermed...