PURPOSE Our purpose was to define the role of dental bur fragments in producing metal artifacts on MR images. METHODS Dental prosthetic reconstructions were made for two dogs. The two lower second premolars were prepared for full-cast crowns by using a diamond bur. The crown margin was placed subgingivally on the right side (1 mm below the free gingival margin) and at the same level as the fr...

AIM A common problem related to cemented single crowns is the internal misfit, which may cause inadequate retention, especially when seated on the implant abutment. The aim of this study was to compare the internal fit of Co-Cr crowns using a traditional lost-wax casting technique from laser-sintered Co-Cr alloy crowns. MATERIALS AND METHODS Twelve metallic crowns per each technique were fabr...

The reaction of bis-(anthracene)cobaltate(-I) with excess cyclo-hepta-triene, C7H8, resulted in a new 18-electron cobaltate containing two different seven-membered ring ligands, based on single-crystal X-ray diffraction. The asymmetric unit of this structure contains two independent cation-anion pairs of the title complex, [K(18-crown-6)][Co(η(3)-C7H7)(η(5)-C7H9)], where 18-crown-6 stands for 1...

We review crown ether-facilitated nucleophilic reactions using metal salts, presenting the studies kinetic measurements and quantum chemical methods. focus on mechanistic features, specifically contact ion-pair (CIP) mechanism of salts for processes promoted by ethers derivatives. Experimental verification CIP form salt CsF complexed with [18-Crown-6] H-NMR spectroscopy is described. The use ch...

Metal ceramic partial fixed dental prostheses have been commonly used for the replacement of missing teeth for many years. Because of an increase in the price of gold, base metal alloys have been the choice of alloy for the fabrication of metal ceramic restorations in many dental clinics. Some major disadvantages of base metals are their corrosion and the dark coloration they may cause at the c...

crestal bone loss is a biological complication in implant dentistry. the aim of this study was to compare the effect of progressive and conventional loading on crestal bone height and bone density around single osseointegrated implants in the posterior maxilla by a longitudinal radiographic assessment technique.twenty micro thread implants were placed in 10 patients (two implants per patient). ...

A new heteroditopic chemosensor based on the 1,3-alternate conformation of thiacalix[4]crown shows a ratiometric fluorescence response towards Hg(2+) ions. Further, a negative allosteric behaviour between Hg(2+)/Li(+) ions is observed. Thus, metal ion exchange triggers a Hg(2+)/Li(+) switchable fluorescent chemosensor.

A crown-shaped organic-inorganic hybrid polyoxomolybdate, Na5[H7{N(CH2PO3)3}Mo6O16(OH) (H2O)4]4·18H2O (1) has been presented and characterized. Such an intriguing structure consists of a 24-molybdenum-membered polyanion constructed by organotriphosphonate ligands, which represents the highest nuclearity of metal atoms in the area of organophosphonate-based polyoxometalates.