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At least 973 records · Page 54Linked to original sources
PubMed1995

[A new direction in the development of Russian silver amalgams. I. The physical research].

A new in principle, ecologically safe and low-waste technology for preparation of an alloy and a formula of several silver alloys containing different levels of silver (OCTA-43, 70 and 80) have been developed. The absence of a alpha-2 phase in amalgams prepared from these alloys is their principally new feature. Physical properties of the new alloys were studied and compared with the known Russian and foreign analogs. Amalgam prepared from CCTA-43 alloy is characterized by optimal characteristics. By their physical characteristics the new compositions are superior to traditional and silver alloys manufactured in Russia at present, and amalgam prepared from OCTA-43 alloy is not inferior to the best foreign analogs.

Color↗
PubMed1995

Titrimetric determination of captopril in dosage forms.

Two titrimetric methods are proposed for the determination of captopril in pure form or in tablets. In the first method iodide selective electrode is used for indirect titrimetric assay of captopril. This compound forms silver salt in presence of excess silver ions, the excess silver ions are determined potentiometrically with standardized iodide solution and an iodide selective electrode. The second method involves the titrimetric determination of captopril using a new oxidimetric titrant 2.3-dichloro-5.6-dicyano-1.4-benzoquinone (DDQ) in anhydrous acetic acid. The equivalent point is detected potentiometrically using calomel and platinum electrodes. The two methods allow semimicro-determination of captopril, the results by the proposed procedures are in good agreement with those obtained by the official method.

Benzoquinones↗
PubMed1994

[Influence of ceruloplasmin on the embryotoxic effect of silver ions].

The effect of alimentary administration of silver salts upon embryogenesis in rats has been studied. Feeding of AgCl to pregnant female rats throughout gestation did not result in any alterations in their physiological functions, although the active copper-containing ceruloplasmin (Cp) was eliminated from the blood stream. However, anomalous development of embryos, their prenatal death or total mortality of newborn rats within the first 24 hours after birth were evidenced. The copper content in the placenta and embryonic tissues decreased appreciably. The Cu,Zn-superoxide dismutase (SOD) activity was diminished in the cytoplasm of embryonic cells alongside with its drop, though less pronounced, in the tissues of the pregnant females. The embryotoxicity of AgCl was considerably reduced by repetitive injections of native Cp to pregnant rats. Such treatment caused an increase in the SOD activity in the placenta and embryonic tissues. Mortality of the newborns also went down. It is suggested that the embryotoxic effect of AgCl is due to its ability to interfere with copper metabolism, by altering the copper-transporting function of Cp.

Animals↗
PubMed1993

The dark choroid in systemic argyrosis.

Argyrosis is a cutaneous discoloration caused by silver. Ocular involvement, including conjunctival and corneal discoloration, has been previously reported. To our knowledge, a retinal involvement was never reported and no data is available about fluorescein angiography patterns of patients with argyrosis. Fluorescein angiography was performed in six consecutive patients with iatrogenic systemic argyrosis. A dark choroid was observed in each case. Red light monochromatic pictures disclosed a leopard spot pattern on the fundus, which was more clearly revealed in one patient by infrared light pictures. These findings suggest that the silver deposit in Bruch's membrane may be responsible for the obscuration of choroidal fluorescence during dye transit and for the visualization of choriocapillary units in pictures using long-wavelength light. The dark choroid is not only present in central retinal dystrophies, but may be observed in other conditions, such as systemic argyrosis.

Adult↗
PubMedDate not supplied

The electrified drain. A new device for sterilizing the field of drainage.

A randomized control study was performed on 24 patients to evaluate the effect of a new drainage system. Two types of drains were used: electrified and the conventional corrugated rubber drains. All of the 24 patients had an incisional hernia repair operation. In 12 patients, the wound was drained with an electrified drain (ED) and in the other 12 by the conventional drain (CD). The ED consisted of a corrugated rubber drain to which 2 silver-silver chloride electrodes were fixed. The wounds were drained for the first 3 post-operative days during which antibiotics were given. A peroperative and daily swab from the wound was taken during the time of drainage and for 4 days thereafter, and cultured. For evaluation, a pathogen count of less than 10(5) colony-forming units per ml of discharge from wound cultures was considered as successful drainage, while counts above this level were defined as failures. Drainage failure occurred in 4/12 patients (33%) of the CD group. Pathogens encountered were Streptococcus pyogenes, Staphylococcus aureus and albus and P. aeruginosa. Manifestations of wound inflammation occurred in 2 of the 4 patients. The appropriate antibiotic was given to the 4 patients after culture and sensitivity tests were performed. Drainage failure did not occur in any of the ED group. Post-operative laboratory assessment of blood count, liver and kidney functions and serum electrolytes recorded insignificant changes against preoperative values in both groups. The results demonstrate the superiority of the ED over the CD. The electric field produced by the ED seems to be lethal to organisms. The ED is simple, safe and cost-effective.

Catheterization↗
PubMedDate not supplied

A clinical comparison of glass ionomer (polyalkenoate) and silver amalgam restorations in the treatment of Class 5 caries in xerostomic head and neck cancer patients.

Fifty-four pairs of restorations (one glass ionomer and the other amalgam) were placed in the mouths of 36 xerostomic head and neck cancer patients. Patients were either fluoride users or fluoride nonusers. In patients who used a daily application of a mildly acidic (pH 5.8) sodium fluoride gel, glass-ionomer cements failed and amalgam restorations did not (P < 0.0001). In patients who neglected to use their topical fluoride as directed, glass-ionomer cement restorations did not fail, but amalgam restorations did (P < 0.001). The mean time to restoration loss for both restorative materials was 8.5 months. In severely xerostomic patients these findings were exaggerated.

Cermet Cements↗
PubMed1995

Safety of silver oxide-impregnated silastic tympanostomy tubes.

Otorrhea occurs after the insertion of tympanostomy tubes in as many as 50% of ears. Although topical antibiotic solutions minimize otorrhea in the immediate postoperative period, recurrent otorrhea is sometimes a clinical problem. The antimicrobial effects of silver oxide when impregnated into a tympanostomy tube may decrease the incidence of recurrent otorrhea. This study demonstrates that silver oxide-impregnated silicone elastomer is well tolerated within the middle ear of gerbils when implanted for 1 year, and the tissue reaction is no more than silicon elastomer without silver oxide. When applied directly to the round window of guinea pigs, there was no evidence of ototoxicity of silver oxide as measured by electrocochleography (N-1 thresholds) and cytocochleography (hair cell counts). These animal studies indicate that silver oxide-impregnated silicone elastomeric tympanostomy tubes may be used safely in clinical trials to determine efficacy.

Animals↗
PubMed1995

The resistance to deformation forces of endodontic posts manufactured from six different materials.

Twenty posts of 1.25 mm diameter and 10 of 1.0 mm diameter were cast in 4 different metals, namely, Argenco 4, Argenco 9, Wiron 99 and Rexillium V (5 each). These posts as well as pre-formed wrought stainless steel and titanium posts (5 each of the same diameter) were tested in an Instron machine to a deformation point of one millimetre. Of the cast posts, those of Rexillium proved to be the most rigid but could only withstand 68 per cent of the force that the wrought posts could resist. No statistically significant differences were found between the wrought posts of stainless steel and titanium and between gold and Argenco 9 in the 1.25 mm category and between stainless steel and titanium and Wiron 99, Argenco 9 and gold in the 1.0 mm category.

Chromium Alloys↗
PubMed1995

Artificially formed caries-like lesions around Class II glass ionomer restorations in primary molars.

The aim of this study was to investigate the microleakage around Class II glass ionomer restorations in primary molars. Two different glass ionomer cements and one amalgam control were assessed in vitro by acidified gel technique. Assessment of caries-like lesions was performed using polarized light microscopy. The traditional glass ionomer (Chemfil II) with dentin conditioner provided the highest protection against caries attack and the amalgam restorations provided the least.

Cariostatic Agents↗
PubMed1996

Absorbed dose in AgBr in direct film for photon energies ( < 150 keV): relation to optical density. Theoretical calculation and experimental evaluation.

In the radiological process it is necessary to develop tools so as to explore how X-rays can be used in the most effective way. Evaluation of models to derive measures of image quality and risk-related parameters is one possibility of getting such a tool. Modelling the image receptor, an important part of the imaging chain, is then required. The aim of this work was to find convenient and accurate ways of describing the blackening of direct dental films by X-rays. Since the beginning of the 20th century, the relation between optical density and photon interactions in the silver bromide in X-ray films has been investigated by many authors. The first attempts used simple quantum theories with no consideration of underlying physical interaction processes. The theories were gradually made more realistic by the introduction of dosimetric concepts and cavity theory. A review of cavity theories for calculating the mean absorbed dose in the AgBr grains of the film emulsion is given in this work. The cavity theories of GREENING (15) and SPIERS-CHARLTON (37) were selected for calculating the mean absorbed dose in the AgBr grains relative to the air collision kerma (Kc,air) of the incident photons of Ultra-speed and Ektaspeed (intraoral) films using up-to-date values of interaction coefficients. GREENING'S theory is a multi-grain theory and the results depend on the relative amounts of silver bromide and gelatine in the emulsion layer. In the single grain theory of SPIERS-CHARLTON, the shape and size of the silver bromide grain are important. Calculations of absorbed dose in the silver bromide were compared with measurements of optical densities in Ultra-speed and Ektaspeed films for a broad range (25-145 kV) of X-ray energy. The calculated absorbed dose values were appropriately averaged over the complete photon energy spectrum, which was determined experimentally using a Compton spectrometer. For the whole range of tube potentials used, the measured optical densities of the films were found to be proportional to the mean absorbed dose in the AgBr grains calculated according to GREENING'S theory. They were also found to be proportional to the collision kerma in silver bromide (Kc,AgBr) indicating proportionality between Kc,AgBr and the mean absorbed dose in silver bromide. While GREENING'S theory shows that the quotient of the mean absorbed dose in silver bromide and Kc,AgBr varies with photon energy, this is not apparent when averaged over the broad (diagnostic) X-ray energy spectra used here. Alternatively, proportionality between Kc,AgBr and the mean absorbed dose in silver bromide can be interpreted as resulting from a combination of the SPIERS-CHARLTON theory, valid at low photon energies ( < 30 keV) and GREENING'S theory, which is strictly valid at energies above 50 keV. This study shows that the blackening of non-screen films can be related directly to the energy absorbed in the AgBr grains of the emulsion layer and that, for the purpose of modelling the imaging chain in intraoral radiography, film response can be represented by Kc,AgBr (at the position of the film) independent of photon energy. The importance of taking the complete X-ray energy spectrum into full account in deriving Kc,AgBr is clearly demonstrated, showing that the concept of effective energy must be used with care.

Bromides↗