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Sealing furcation perforations with silver glass ionomer cement: an in vitro evaluation.

Furcation perforations sealed with silver glass ionomer cement (Chelon Silver) were evaluated in vitro compared with amalgam. Access cavities were prepared in 25 extracted human molar teeth. The coronal orifices of the root canals were sealed with amalgam and varnish. Naturally occurring coronal leakage through the intact pulp chamber floor was determined quantitatively for each tooth, using a modified fluid transport model, under pressure of 1.2 Atm. Each tooth was then disconnected from the system, perforated at the furcation, and the perforation sealed with either Chelon Silver (10 teeth) or amalgam (10 teeth); five remaining teeth served as a negative control. After incubation for 24 h at 37 degrees C in 100% humidity, teeth were reconnected to the modified fluid transport system, and coronal leakage under pressure was evaluated at 1, 2, 6, 15, and 24 h. Leakage through each tooth was compared with that of its own intact pulp chamber floor before perforation and the groups compared with each other. No significant difference was found between the mean leakage of the intact pulp chamber floors of the two groups. Chelon Silver had a significantly better sealing ability than amalgam (p < 0.01): leakage rate of 0.007 and 0.017 microliter/min, respectively. It is concluded that Chelon Silver could be an adequate sealer for furcation perforations.

Cermet Cements↗

Increased bacterial burden and infection: the story of NERDS and STONES.

PURPOSE: The purpose of this article is to provide practitioners with an overview of wound infection/inflammation and bacterial balance and to offer a guide to assessment and treatment of chronic wounds. TARGET AUDIENCE: This continuing education activity is intended for physicians and nurses who assess and treat wound infections. OBJECTIVES: After reading this article and taking this test, the participant should be able to: 1. Discuss factors associated with infection of the chronic wound, including the concept of bacterial balance and burden. 2. Identify signs of infection in the chronic wound and applicable diagnostic tests. 3. Describe appropriate treatment for the infected chronic wound.

Abbreviations as Topic↗

Tobacco smoking, nicotine, and nicotine and non-nicotine replacement therapies.

Tobacco smoking is associated with an increased risk for the development of coronary and pulmonary vascular diseases and smoking cessation will greatly reduce this risk. Nicotine replacement and nonnicotine modalities have been used alone and in combination to help in smoking cessation. These treatment modalities appear to be safe in patients with known stable coronary artery disease.

Acetates↗

Therapeutic efficacy of three silver dressings in an infected animal model.

The organic salt AgNO3 has been available as a topical armamentarium to the medical arena for centuries and for burns for the past 60 years. Thirty-five (1968) years later, Charles Fox introduced and popularized a new topical agent known as silver sulfadiazine. More recently, several new slow-release silver dressings came to the forefront. Acticoat (Smith & Nephew, Largo, FL) Silverlon (Argentum, Lakemont, GA) & Silvasorb (Medline Industries, Inc, Mundelein, IL). Because the standard of care is to change dressings daily, our study focused in on weekly dressing changes as a cost-containment issue. Sprague-Dawley rats received a standard contact burn (20% TBSA). On day 3, the wound was excised and infected with Pseudomonas aeruginosa and Staphylococcus aureus at 5.0 x 10 cfu/ml. The animals were divided into four groups (n = 5 each group): untreated control, Acticoat group, Silvasorb group, and Silverlon group. The dressings remained on the wounds for 10 days when the wounds were quantitatively assessed. Mean wound counts of the control ranged from 1.2 x 10(5) to 6.5 x 10(5) for P. aeruginosa and S. aureus, respectively. Acticoat dressing counts for both organisms were 0 and 1.8 x 10(3) (median alpha); Silvasorb was 0 and 6.3 x 10(3) and Silverlon was 1.5 x 10(4) x 7.4 x 10(4) (median), Acticoat and Silvasorb were both significantly lower (P < .05) than the control for P. aeruginosa, and Acticoat was significantly lower (P < .05) than the control for S. aureus. Although counts for Silvasorb (M) appear significantly lower than the controls for S. aureus, the numbers were not sufficient to be significant. However, Silverlon did achieve a slight significance. These preliminary data suggest that weekly dressing changes with these new silver dressings are feasible and economically and medically congruous.

Administration, Topical↗

Cytotoxicity of direct current with antibacterial agents against host cells in vitro.

The purpose of this study was to investigate the cytotoxicity of iontophoresis treatment using direct current (DC) with or without antibacterial agents. The following antibacterial agents were used: diamine silver fluoride (AgF); sodium fluoride (NaF); and iodine zinc iodide (JJZ). The cytotoxic activity of DC with or without antibacterial agents against human polymorphonuclear cells (PMNs) was evaluated by the 3-[4, 5- dimethylthiazol-2-yl]-2, 5-diphenyltetrazolium bromide (MTT) assay. It was noted that DC (2 mA) killed PMNs in a time-dependent manner and the cytotoxicity was enhanced when DC was combined with antibacterial agents. The toxic effect of antibacterial agents was in the order: AgF>JJZ>NaF. The death of PMNs by DC was evaluated by flow cytometry using annexin V-FITC/propidium iodide staining. DC appeared to induce necrosis rather than apoptosis of PMNs. These results suggest that iontophoresis treatment using DC and antibacterial agents may induce necrotic cytotoxicity in host cells around periapical lesions.

Analysis of Variance↗

Polymorphism in Cs[AgZn(NCS)4].

The title compound, caesium silver zinc tetrathiocyanate, crystallizes in two polymorphic forms, in space groups P2(1)/n and C2/c. Both structures form a continuous three-dimensional network. The structure in C2/c contains a delocalized Ag atom in a binuclear-like anion, where two [Ag(NCS)(4)] units (delocalized Ag as an average) share two common NCS(-) ligands.

Journal Article↗

Silver-silver chloride plunge electrode needles and chloriding monitor.

A plunge electrode is made from a hypodermic needle with one side cut open and multiple electrodes exposed from tip to base. A method for constructing chlorided silver electrode plunge needles is explained as well as problems associated with electrode chloriding. The small surface area of these electrodes makes empirical methods of chloriding difficult to use. A monitor was constructed for the testing and chloriding of a twelve-electrode plunge needle. This system continuously measures the impedance of the electrodes during chloriding.

Electric Conductivity↗

Geometric effects on resistivity measurements with four-electrode probes in isotropic and anisotropic tissues.

We studied via computer simulation the effects of electrode diameter, electrode length, interelectrode spacing, and tissue size on the accuracy of measured tissue resistivities and anisotropy ratios obtained with the widely used four-electrode technique. Such measurements commonly assume an ideal situation in which the four electrodes are infinitesimally small and the tissue is semi-infinite. Our study shows that these geometric factors can significantly affect measured resistivities, particularly for anisotropic tissues. The measured anisotropy ratio is decreased by either 1) increasing the electrode diameter or length relative to the interelectrode spacing of the probe or 2) decreasing tissue size. We have provided an equation for estimating errors in the measured anisotropy ratio from the parameters of electrode and tissue geometries. The simulation findings are supported by our in vitro experimental results.

Animals↗

Characterization of micromachined spiked biopotential electrodes.

We present the characterization of dry spiked biopotential electrodes and test their suitability to be used in anesthesia monitoring systems based on the measurement of electroencephalographic signals. The spiked electrode consists of an array of microneedles penetrating the outer skin layers. We found a significant dependency of the electrode-skin-electrode impedance (ESEI) on the electrode size (i.e., the number of spikes) and the coating material of the spikes. Electrodes larger than 3 x 3 mm2 coated with Ag-AgCl have sufficiently low ESEI to be well suited for electroencephalograph (EEG) recordings. The maximum measured ESEI was 4.24 k(omega) and 87 k(omega), at 1 kHz and 0.6 Hz, respectively. The minimum ESEI was 0.65 k(omega) an 16 k(omega), at the same frequencies. The ESEI of spiked electrodes is stable over an extended period of time. The arithmetic mean of the generated dc offset voltage is 11.8 mV immediately after application on the skin and 9.8 mV after 20-30 min. A spectral study of the generated potential difference revealed that the ac part was unstable at frequencies below approximately 0.8 Hz. Thus, the signal does not interfere with a number of clinical applications using real-time EEG. Comparing raw EEG recordings of the spiked electrode with commercial Zipprep electrodes showed that both signals were similar. Due to the mechanical strength of the silicon microneedles and the fact that neither skin preparation nor electrolytic gel is required, use of the spiked electrode is convenient. The spiked electrode is very comfortable for the patient.

Anesthesia, General↗