Considering the psychosocial aspects of AIDS

People with AIDS have great needs--not only physical due to the effects of the disease on their bodies, but psychological as well. In addition, fear and repugnance of the disease and its victims has started another epidemic dubbed AFRAIDS.

Osteogenesis imperfecta lethal in infancy: case report and scanning electron microscopic studies of the deciduous teeth

Radiologic evaluation of the skeleton and scanning electron microscopic studies of the teeth were performed on an infant boy with a lethal osteogenesis imperfecta (OI) syndrome who died at 10 mo of pneumonia. The skeletal findings included ribs that were focally expanded by fracture calluses, flat vertebral bodies, and wide limb bones. On fractured tooth surfaces, the enamel and dentin were normal as was the dentin calcification front. Although microscopic abnormalities have been noted in teeth from previously reported infants with lethal OI, a few studies also report infants with normal teeth. These differences in dental findings may indicate heterogeneity in OI lethal in infancy. Results of our study indicate that, until the primary biochemical defects in the OI syndromes are elucidated, examination of teeth from other infants with lethal OI and detailed evaluation of other clinical and skeletal features will aid in delineating heterogeneity and variation in expression in lethal OI.

Light microscopy, scanning electron microscopy, and microprobe analysis of bone response to zinc and nonzinc amalgam implants

Freshly mixed, unset zinc-free and zinc-containing analgam was implanted in the right tibia of 32 rats. Half of the specimens were examined by the light microscope and the other half by the scanning electron microscope and x-ray microprobe analysis. It was found that amalgam is well tolerated by the rat osseous tissue, and there were no histologic reaction differences between zinc and zinc free amalgam. The surfaces of the implants were covered by an organic film at 3 weeks and with bone at later intervals. Very little corrosion products containing sulfur were observed on the amalgam surface at all intervals. Bone adjacent to the amalgam contained tin and sulfur irrespective of the presence of zinc in the alloy, indicating outward migration of specific components of the alloy.

Scanning electron microscopy of teeth in dominant osteogenesis imperfecta: support for genetic heterogeneity

Scanning electron microscopic studies were performed on 25 deciduous and permanent teeth from members of 7 kindreds with dominant nonlethal osteogenesis imperfects (OI). Two families had normal teeth on clinical and radiological examination; five families had blue or brown opalescent teeth with specific radiologic findings. Enamel surfaces and prism organization were normal on all teeth. On fractured surfaces, the dentin tubules of normal teeth from patients with OI were evenly distributed and coursed regularly to the dentin-enamel junction. Opalescent teeth had few tubules and those present were short, narrow, and tortuous. Dentin calcification fronts of normal teeth were composed of many nodules with regularly spaced openings on their surfaces. Calcification fronts of opalescent teeth were composed of irregularly spaced, small nodules, which varied greatly in size and the nodules lacked tubule openings on their surfaces. The results of this study support the concept that at least two dominant forms of OI exist--one in which all individuals with IO have normal teeth, and the other in which all with OI have blue or brown opalescent teeth with characteristic changes on SEM.

Periodontosis: a case report with scanning electron microscopic observations

A tooth and associated periodontal tissues from a patient with the diagnosis of periodontosis was subjected to scanning electron microscopic evaluation after reflection of the soft tissue portion of the lingual defect. The cemental surface of the apical portion of the lesion was found to be populated by markedly similar rod-shaped organisms. The microorganisms were observed to be continuously present in a coronal-apical direction as the transition from cementum to the attached soft tissues at the base of the defect were examined. These findings provide additional evidence that the lesion of periodontosis is characterized by a rather distinct microbial population of rod-shaped organisms located predominately at the base of the defect.

Sealing quality of a temporary filling material

Endodontic access cavities were prepared in forty extracted human teeth. The access cavities were obturated with Cavit and tested for leakage with methylene blue. The data suggested that at least a 3.5 mm. thickness of Cavit should be used in order to prevent leakage. Examination under the scanning electron microscope showed areas in which the constituents of Cavit were improperly mixed, which may lead to increased penetration.

Evaluation of débridement techniques for endodontic instruments

Files, reamers, and Hedström files were used to instrument both wet and dry canals and then cleansed by a chairside technique. Statistical analysis of the various cleansing techniques showed that 2 by 2 inch gauze wipes, either wet or dry, cleansed the instruments of debris better than any other means tested.

Degradation rates of oral resorbable implants (polylactates and polyglycolates): rate modification with changes in PLA/PGA copolymer ratios

This study determined the difference in rate of degradation between pure polymers of lactic acid (pla), glycolic acid (PGA), and various ratios of copolymers of these two substances. Fast-cured and slow-cured polyglycolide was compared with copolymers of glycolide/lactide intermixed in ratios of 75:25, 50:50, and 25:75, as well as pure polylactide. A total of 420 rats were implanted with carbon-14 and tritium-labeled polymers in bone and soft tissue. At intervals of 1, 2, 3, 5, 7, 9, and 11 months, groups of five animals with the implants in bone and five with the implants in the abdominal wall were sacrificed. The implant area as well as tissue from the liver, spleen, kidney, lung and some muscle tissue was analyzed for radioactivity along with the urine and feces collected throughout the experiment. Half-lives of the different polymers and copolymers were calculated from the radioactivity present in the implant area for each time interval. Half-life of the polymers and copolymers decreased from 5 months for 100% PGA to 1 week with 50:50 PGA:PLA copolymer and rapidly increased to 6.1 months for 100% PLA. Fast-cured PGA had a half-life in tissue of 0.85 months. No difference in rate of degradation was seen in soft tissue or bone. No significant radioactivity was detected in urine, feces, or tissue samples. From this study, it is concluded that control of degradation rate of the implant could best be attained by varying the composition of PLA and PGA between 75% and 100% PLA along with a corresponding 25% to 0% PGA. This would provide a half-life range of the implant of from 2 weeks to 6 months.

Evaluation of endodontic instruments as received from the manufacturer: the demand for quality control

Two hundred seventy new files, reamers, and Hedström files from three different manufacturers were evaluated for debris and defects. Statistical analysis of the new instruments showed that one company's instruments were cleaner than the other two but still contained defects. A standard for quality is proposed.

The electron microscopy of bacteriophage-like particles in dental plaque

The morphology of bacteriophage-like particles contained in samples of dental plaque is described. The phage-like particles were observed within fusiform-shaped bacteria and in clumps between bacteria. The particles were hexagonal in cross section, approximately 1,100 nm in diameter and contained an electron-dense core. In areas of cell lysis tail forms were observed both free and in association with the particles. Occasional particles were attached to bacterial cell walls by means of shortened tailpieces.

Scanning microscopic evaluation of canal débridement as compared to present methods

Ninety-one samples of root canal contents were obtained from thirty-one teeth. The paper point samples were evaluated for exudate, subjected to bacteriologic analysis, and/or examined with the scanning electron microscope. A comparison was made between the presence or absence of exudate, positive and negative cultures, and the presence or absence of contaminants as examined under the SEM. All three methods of evaluation showed some degree of correlationmscanning electron microscopy appears to be a more sensitive test for canal status.

Scanning microscopy of cervical erosion

The dentitions of 900 dentists were examined for the presence of cervical erosion. Of these, 48 individuals of 5.3% had obserable erosion. Silicone impressions were made of the eroded labial surfaces in a typical quadrant, and epoxy resin models were constructed. These were examined in the scanning electron microscope. Cross sections of the replicas were examined in the light microscopy. Of the 48 replicas (24 of the maxilla and 24 of the mandible), the most severe erosion was found on the first premolars in 62% of the individuals, on second premolars in 19% on cuspids in 12%, and on first molars in 6%. The margin of the defect toward the gingiva was level with or just below and parallel to the gingival crest. The erosion pattern was distinguished by two shapes--an angular lesion with a flattened floor associated with deep lesions (68%), and a rounded, smaller defect with no sharp interior angles and less tooth damage (32%). It is postulated that cervical erosion may result from two different mechanisms--a more common, destructive process, angular and deep; and a less severe, shallow process with rounded form.

Scanning electron microscope study of scalers

Scanning electron microscopy was used to examine factory-sharpened, dulled, and resharpened scalers. The following observations were made: 1. The factory sharpened scalers exhibited metallic extensions from the lateral surface (wire edges). 2. The machine-resharpened instruments resulted in nonfunctional wire edges from the facial surface. Honing produced an exact meeting of facial and lateral surfaces. 3. Hand sharpening, using an Arkansas stone (grit 500) against the lateral surface away from the cutting edge, effected an exact meeting of the facial and lateral surfaces and no evidence of wire edges. 4. From this study an optimum cutting edge for a scaler is characterized as having a smooth, contiguous meeting of the facial and lateral surfaces free of wire edges. If a wire edge is present, it should be functional.

Findings in 1,724 buccal smears from dentists

No changes were found in the epithelial cells from the buccal mucosa of dentists with the use of the light microscope, electron microscope, or electron probe that could be correlated with mercury exposure under the conditions of this test. In a normal population it can be expected that at least 0.01% of the population will show class 2 atypical smears. Patients with class 2 smears have fewer highly matured epithelial cells (tendency toward keratinization) of the buccal mucosa and hence a thinner epithelium.

Corrosion of silver cones in bone: a scanning electron microscope and microprobe analysis

Sections of silver cones were implanted in tibial bone wounds in 36 Sprague-Dawley rats. Groups of six rats each were killed at monthly intervals, and the specimens were examined by scanning electron microscopy and by X-ray microanalysis. The silver cones had corroded rapidly, but they were well tolerated by the tissues. Elements of silver, chlorine, and sulfur were found in the tissues adjacent to the implants.

Postdebridement retention of endodontic reagents: a quantitative measurement with radioactive isotope

Forty freshly extracted human teeth were biomechanically prepared for endodontic obturation using a radioisotopically labeled EDTA-urea peroxide-Carbowax compound. The amount of radiolabeled mixture remaining in the canals after through cleansing was about 3.8% of that originally applied. The amount of residue did not decrease with reinstrumentation and irrigation.

Localization of bacteria on the rat tongue with scanning and transmission electron microscopy

Scanning microscopy of rat tongue showed that bacterial habitation of the tongue was almost completely localized to the middle third of the anterior surface of the filiform papillae. Transmission microscopy showed coccal forms attached to the surface of the epithelium by means of fibrillar strands and present up to four cell layers deep within the epithelium.

Corrosion of endodontic silver cones in humans: a scanning electron microscope and X-ray microprobe study

Analyses with the scanning electron microscope and the X-ray microprobe were performed on 13 silver cones removed from 12 patients. The cones showed changes that ranged from surface dulling to black corrosion and pitting. Sulfur and chlorine were detected at the apical end of the cones and in the biopsy specimens of periapical tissues.

Ouabain-sensitive adenosine triphosphatase from human kidneys

Adenosine triphosphatase (ATPase) was studied in tissue homogenates and subcellular fractions derived from human cadaver kidneys maintained in an organ preservation unit for transplantation. The activity of ouabain-sensitive ATPase was highest in the medulla, intermediate in the cortex and lowest in the papilla, The cortical enzyme activity diminished with time during maintenance perfusion of the kidneys. Similar concentrations of K+, Na+, Mg++, ATP and MgATP were required for half-maximal rates of ouabain-sensitive ATPase activity from the cortex or the medulla. The sensitivity of the enzyme to ouabain from both parts of the kidney was similar. K+ antagonized inhibition of the enzyme by ouabain. Chlormerodrin, mersalyl, mercaptomerin and ethacrynic acid were inhibitors of the enzyme.

The effects of two ultrasonic instruments on root surfaces

The Orbison ultrasonic instrument and the Cavitron ultrasonic dental unit were compared for the smoothness of the root surfaces they produced. Twenty teeth were analyzed with the scanning electron microscope and classified as to rough or smooth. Both instruments produced similar degrees of smoothness on the root surfaces with minimal scarring. Application of these instruments to the root surface apical to the epithelial attachment produced residual smearing of some of the collagenous fibrils.

Oubain-sensitive adenosine triphosphatase from human kidneys

Adenosine triphosphatase (ATPase) was studied in tissue homogenates and subcellular fractions derived from human cadaver kidneys maintained in an organ preservation unit for transplantation. The activity of ouabain-sensitive ATPase was highest in the medulla, intermediate in the cortex and lowest in the papilla. The cortical enzyme activity diminished with time during maintenance perfusion of the kidneys. Similar concentrations of K+, Na+, Mg++, ATP and MgATP were required for half-maximal rates of ouabain-sensitive ATPase activity from the cortex or the medulla. The sensitivity of the enzyme to ouabain from both parts of the kidney was similar. K+ antagonized inhibition of the enzyme by ouabain. Chlormerodrin, mersalyl, mercaptomerin and ethacrynic acid were inhibitors of the enzyme.

Electron microscopic study of the effect of water jet lavage devices on dental plaque

The maxillary posterior teeth of nine rhesus monkeys were treated with a pulsating water lavage instrument at 70 psi (high setting). Electron microscopic studies of pre- and post-lavage plaque samples showed that water jet devices as used in this experiment either removed the plaque completely or caused irreversible damage to the microbial forms in the plaque matrix.

Transition of chemolithotroph Ferrobacillus ferrooxidans to obligate organotrophy and metabolic capabilities of glucose-grown cells

Transition of chemolithotrophic Ferrobacillus ferrooxidans to organotrophy occurred after 60 hr of incubation in an organic medium. Three distinct phases, based on metabolic activities of cells, were observed during the course of transition. Conversion of cellular nutrition to organotrophy resulted in a gradual loss of Fe(2+) oxidation and cessation of CO(2) fixation. These changes were concomitant with a rapid increase in uptake of glucose and phosphate during the latter part of transition period. The outcome of transition was governed by the pH of the medium, temperature of incubation, availability of oxygen, age of the chemolithotrophic cells, and the type of energy and carbon source available to the bacterium. Presence or absence of p-aminobenzoic acid and Fe(2+) ions did not influence transition of cells. A defined medium containing glucose, mineral salts, and p-aminobenzoic acid at pH 2.5 was found to be most suitable for transition and for culture of heterotrophic convertants. Maximum growth rate of the heterotrophic cells was attained with vigorous aeration at 35 C. The bacterium could be cultured on a variety of organic compounds, including complex organic media, provided they were used in low concentrations. Serological studies on autotrophic cells and the heterotrophic convertant have shown a definite antigenic relationship between the two cell types.