UNLABELLED Screw-retained implant crowns may be clinically demanding, especially managing the esthetic and occlusal challenges of screw access channel closure. Many clinicians have moved away from using screw retention as a means of fixing a crown to an implant in favor of cementation to an underlying abutment. A link has been established between peri-implant disease and excess cement extrusion...

The general dental practitioner must consider orthodontic extrusion of a tooth when a subgingival defect, such as, crown fracture occurs before prosthetic rehabilitation, especially in the aesthetic zone. Extrusion enables the root portion to be elevated which exposes sound tooth structure for placement of restorative margins. This case report describes the multidisciplinary management of a fra...

The 1-piece, implant-supported abutment and crown, colloquially described as the UCLA abutment, commonly is used to fabricate single, screw-retained crowns. This abutment was designed to allow attachment of the crown directly to the implant and requires a waxing and casting procedure by a laboratory technician. A new prefabricated abutment has been developed that uses a similar approach but doe...

Crown ether complexation solubilizes organic and inorganic salts in nonpolar media. Induction of crystallization from such solutions can result in crystallization of the free salt rather than the complex. This affords the opportunity to examine solvent effects on the crystallization of salts and other polar materials, leading to the modification of crystal shape and lattice. This approach, whic...

Introduction: Different treatment approaches are indicated for crown-root fractured teeth. Surgical extrusion is a onestep procedure that implies immediate repositioning of the tooth into its normal position. The aim of this case report was to report the multidisciplinary treatment of a crownroot fractured maxillary premolar. Methods: In this case, a crown-root fractured maxillary premolar was ...

In the title compound, [Zn(C44H28N4)]·C12H24O6, the Zn(II) ion lies on an inversion center and the asymmetric unit contains one half of a Zn(TPP) complex (TPP = 5,10,15,20-tetra-phenyl-porphyrin dianion) and one half of a centrosymmetric 18-crown-6 mol-ecule. The Zn(TPP) complex exhibits a nearly planar conformation of the porphyrin core [maximum deviation = 0.106 (2) Å] with an average Zn-N di...

STATEMENT OF PROBLEM Static and dynamic occlusal interference frequently needs to be corrected by selective grinding of the occlusal surface of conventional cast and ceramic-fused-to-metal restorations. CAD/CAM techniques allow control of the dimensional contours of these restorations. However, parameters responsible for the occlusal form need to be determined. In most articulators, these param...

A conductance study of the interaction between Cs+, Rb+, NH4+, K+, T1+ and Ag+ ions and18-crown-6 (18C6), benzo-18-crown-6 (B18C6), dicyclohexyl-18-crown-6 (DC18C6),dicyclohexyl-24-crown-8 (DC24C8), dibenzo-24-crown-8 (DB24C8) in different binarymixtures of acetonitrile (AN) with dimethylsulfoxide (DMSO) and dimethylformamide (DMF)at 25 °C has been carried out. Formation constants of the result...

The formation of alkali-metal ion complexes with the crown ethers, 18-crown-6(18c6), benzo-18c6 and dibenzo-18c6 has been investigated. Theoretical studies of structural changes on complexation, binding energies and changes in electron distribution have been carried out using ab initio quantum theoretical methods. A complementary study of the NMR chemical shifts and coupling constants has also ...