BACKGROUND Studies regarding the effect of various methods to increase the surface hardness of Type IV dental stone are not conclusive. Therefore, this study was carried out to evaluate the effect of air drying, micro oven drying and die hardener on surface hardness of Type IV dental stone. MATERIALS AND METHODS A standard metal die was fabricated; polyvinyl siloxane impression material was u...

STATEMENT OF PROBLEM Fracture strength of interim fixed partial prosthesis is of great concern, especially in long-span restorations or areas of heavy occlusal stress. PURPOSE Effects of a plasma-treated woven polyethylene fiber (Ribbond) on the fracture strength of polymethyl methacrylate (Coldpac) and a resin-based two-phase curing provisional restorative material (Provipont DC) were evalua...

Cyclopentadienyl (Cp)-coordinated cationic Si(II) (1) and Ge(II) compounds (2) are a new class of catalysts for various transformations in organosilicon chemistry. This review demonstrates that these effectively catalyze technically important reactions, such as the hydrosilylation carbon-carbon multiple bonds types siloxane-coupling e.g., Piers-Rubinsztajn reaction oxidative siloxane coupling r...

In this paper, we studied a new preparation method of microcapsules for entrapment of genetically engineered cells. Polyvinyl alcohol microcapsules having well defined shape, high mechanical strength, good biochemical and permeability properties were prepared by using low temperature physical cross-linking method. Comparing with currently used alginate-polylysine-alginate microcapsules, polyvin...

STATEMENT OF PROBLEM In complete mouth reconstructive dentistry, the occlusal vertical dimension may be increased to provide adequate restorative space or to improve esthetics. The effect of increasing the occlusal vertical dimension on the smile is not well understood. PURPOSE The purpose of this study was to evaluate the effect of increasing the occlusal vertical dimension on the dimensions...

Figure 1.Maxillary PVS impression demonstrating defect in palatal region. A maxillary complete denture (CD) impression often demonstrates a defect in the palatal region of the edentulous arch. This problem commonly relates to air trapped in the impression material or mishandling of the tray seating; the bubble formed in the impression can compromise the fit of the CD or impair tissue health. On...

The ability of β-cyclodextrin, hydroxypropyl-β-cyclodextrin, polyvinyl pyrrolidone and urea to influence the percutaneous absorption of meloxicam through isolated rat skin was evaluated. Carrier complex were prepared by kneading method in 1:1 and 1:2 in molar ratios for β-cyclodextrin and hydroxypropyl-β-cyclodextrin and in 1:1, 1:3 and 1:5 in weight ratios for polyvinyl pyrrolidone and urea. T...

Several polysiloxanes (polydimethyl, polymethyloctadecyl or polymethyltetradecyl-siloxane) were studied by FTIR spectroscopy, densimetry and gel permeation chromatography. Different types of ageings such as thermal ageing (60°C and 100°C), photo-ageing (SEPAP) and acid vapour ageing were performed and compared. Oxidation, chain scission and cross-linking were estimated after ageings. The presen...

Pure gas permeability coefficients of a series of copolymers based on polar, hydrophilic poly(ethylene glycol) dimethacrylate, n 1⁄4 14 (PEGDMA) and siloxane-based co-monomer, [methyl bis(trimethylsiloxy) silyl] propyl glycerol methacrylate (SiGMA) are reported. SiGMA is miscible with PEGDMA and able to form homogeneous films. SiGMA contains a bulky siloxane-based end group, which acts to incre...