Biomedical subjects
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Two hundred forty-seven patients, followed up a mean of 18 months and up to 108 months, were retrospectively studied for problems related to or affecting tracheoesophageal puncture for voice restoration. Active cases, as well as those inactive and decreased, were included. There were 154 patients with primary and 93 with secondary tracheoesophageal puncture. Problems were encountered at least once in 137 cases (55%). The 20 types of problems identified occurred in frequencies ranging from 0.4% to 21%. Most difficulties developed within the first 6 months and in general were easily managed. However, problems such as recalcitrant leakage, difficulty with changing the prosthesis, and dislodgment of the prosthesis led to permanent tracheoesophageal puncture tract closure in 18 patients (7%).
Solid core filling material such as gutta-percha has been used to fill the root canal in conjunction with a sealer to prevent apical leakage. The purpose of this study was to compare apical seal of five different root canal sealers. Sixty roots of maxillary central incisors were cleansed and shaped and randomly assigned to one of six groups of ten roots each. The root canals were obturated with gutta-percha and one of the sealers by the lateral-vertical condensation technique. Groups I, II, III, IV, and V consisted of roots in which the canal was filled with gutta-percha along with either Roth's sealer, AH26, Sealapex, CRCS, or Nogenol sealer, respectively. Group VI was filled with gutta-percha and without sealer to serve as a control. The access opening was filled with amalgam. Each tooth was then placed in a capped vial containing 2 X 2 inch gauze pads saturated with distilled water, and the sealer was allowed to set at 37 degrees C in the humidor for 48 hours. The roots, except for the apical 2 mm, were coated with two layers of nail polish. The roots were stained with india ink, decalcified, dehydrated, and then placed in methylsalicylate to make them transparent. The leakage was measured with a filar micrometer eyepiece under a dissecting microscope. The mean apical leakage of six groups was as follows: I = 0.45 mm, II = 0.277 mm, III = 0.343 mm, IV = 0.263 mm, V = 0.336 mm, and VI = 2.310 mm. Results showed no significant difference in the apical seal produced by gutta-percha and the tested root canal sealers.(ABSTRACT TRUNCATED AT 250 WORDS)
The specific acoustic impedance of the piezoelectric composites over the frequency range of 0.5-7.5 MHz was measured using the reflection, the echo-shift, and the resonance techniques. There was a significant difference between the values obtained by the reflection technique in comparison with the other two techniques. It is argued that the difference is inherent in the measurement techniques and they measure different properties of the composite such as acoustic impedance and reflectivity. The specific acoustic impedance and the reflectivity were found to be a function of the volume fraction of the ceramic and not a function of frequency.
The effects of steriodal and nonsteroidal antiinflammatory agents on mortality, plasma glucose and lactate levels, and pathologic alterations associated with Escherichia coli endotoxemia were assessed in neonatal rats. Animals were first injected subcutaneously with either high (LD95) or moderate (LD35) doses of endotoxin and immediately thereafter were administered either saline, dexamethasone, indomethacin, or glucose. Animals treated with saline or glucose developed significant hypoglycemia and hyperlactacidemia. Dexamethasone and indomethacin ameliorated the fall in glucose and the rise in lactate during high dose but not moderate dose endotoxemia. Pathologic changes consisting of widespread inflammation and hepatic necrosis were most marked in the saline- and indomethacin-treated animals. Only dexamethasone significantly reduced mortality at either LD95 or LD35 doses of endotoxin. We conclude that dexamethasone may reduce mortality in endotoxic shock through mechanisms other than simple amelioration of changes in plasma glucose.