Objectives Impression accuracy is the main determinant of the fit, form and function of prosthetic restorations. Polyvinyl siloxane (PVS) is the material of choice in most clinical situations. The purpose of this paper is to provide an up-to-date review of scientific articles which discuss the dimensional accuracy of PVS impression material using various impression techniques, tray types and sp...

Octamethylcyclotetrasiloxane (OMCTS), a common constituent of household products, triggers the transformation of bismuth to the volatile toxic derivative trimethylbismuth by Methanosarcina barkeri, which is a representative member of the sewage sludge microflora. Comparative studies with the ionophores monensin and lasalocid, which induce effects similar to those observed for OMCTS, indicated t...

The diverse e4orts to rationally construct microporous solids using porphyrins and metalloporphyrins as molecular building blocks are reviewed. Porphyrin-based molecular crystals, hydrogen-bonded networks, and metal ion coordination polymer networks are examined in detail. Recurring geometrical motifs observed in the structural frameworks of di4erent porphyrinic solids are emphasized, and the i...

This article describes a simple procedure of recording contours of an existing cast post and core that needs to be reconstructed, using a polyvinyl siloxane material as a matrix for fabrication of a new cast post and core in a relatively short time with reduced cost. The procedure involves the use of an acrylic resin material under pressure, which minimizes void formation in the post-and-core p...

Sol-gel derived poly(oxyethylene)/siloxane hybrids doped with lithium hexafluoroantimonate, LiSbF6, have been prepared. Compositions of these novel xerogel electrolytes were identified using the conventional d-U(2000)nLiSbF6 notation, (where n is the molar ratio of oxyethylene moieties per Li + ion) and samples with n between ∞ and 2.5 were characterized by conductivity measurements, cyclic vol...