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Biomedical subjects

J Theilade

Publications and source records attributed to J Theilade.

At least 37 records · Page 2Linked to original sources
PubMed1981

Method for studying the development, structure and microflora of denture plaque.

Pieces of sandblasted, self-adhesive tape were stuck to the fitting surface of maxillary dentures in 17 edentulous subjects with clinically normal palatal mucosa. After 1 week, during which the subjects abstained from denture hygiene, the tape samples were removed for cultural and microscopical examinations. The microorganisms were suspended in RTF by ultrasonic treatment and total viable anaerobic counts and viable counts of yeasts per cm2 of tape were calculated after inoculation of serial dilutions on nonselective medium and sabouraud agar. Total anaerobic viable counts ranged from 4 X 10(4) to 5 X 10(8). By repeated sampling the largest intra-individual variation was 10-fold, only. Yeast counts constituted less than 1% of the total viable counts in all but two of the subjects. Light and electron microscopy showed a bacterial plaque of predominantly cocci and rods.

Aged↗
PubMed1981

Ultrastructural estimation of the effect of sucrose and glucose rises on early dental plaque formed on plastic films.

The influence of water, glucose and sucrose rises on early plaque formation has been studied. The amount and structure of dental deposits formed on plastic films were determined on four occasions: no rinsing, water, glucose or sucrose rinses. Five subjects with healthy gingiva developed plaque in 4 h on plastic films applied to the buccal surfaces of premolars and canines, after which period the plastic films with adhering deposits were processed for electron microscopy. Sections were prepared for examination in the light and electron microscope. Some were stained for the demonstration of carbohydrates according to the periodic acid thiocarbohydrazide osmium tetroxide technique. Furthermore, the number of cellular elements collected on the films during the four experiments was calculated and statistically compared. The results in the four groups were identical. The plastic films were covered by a surface coating of acellular material in or on which bacteria, epithelial cells and leukocytes were observed. The microorganisms were almost exclusively Gram-positive cocci. Many bacteria exhibited intracellular polysaccharides. The results indicate that the rinsing procedure does not influence early plaque formation, and that frequent mouthrinses with glucose or sucrose have no detectable effect on plaque growth at this initial stage of bacterial adherence.

Adult↗
PubMed1980

Influence of optimal and excluded oral hygiene on early formation of dental plaque on plastic films. A quantitative and descriptive light and electron microscopic study.

The influence of oral hygiene on early plaque formation has been studied. The amount and structure of dental deposits formed on plastic films were determined at two occasions with or without a preceding period of effective oral hygiene. Six human subjects developed plaque during 4 hours on plastic films applied to the buccal surfaces of premolars and cuspids. The plastic films with adhering deposits were processed for electron microscopy. In presence of healthy gingiva, the plastic films were covered by a surface coating of acellular material in or on which bacteria, epithelial cells and leukocytes were observed. The microorganisms were almost exclusively Gram-positive cocci. When plaque formation was preceded by a week of excluded oral hygiene, the deposits collected on the same teeth exhibited a threefold increase in the number of bacteria. The relative composition of the flora was altered, as evidenced by a higher number of Gram-negative cells as well as the occurrence of rods and filamentous organisms. The results indicate that neglect of oral hygiene favors an earlier establishment of a complex bacterial flora at the dento-gingival region of the buccal surfaces of premolars and cuspids.

Adult↗
PubMed1980

Electron microscopic study of denture plaque.

This study was designed to gain information on the composition and ultrastructure of bacterial plaque on the fitting surface of maxillary dentures in edentulous patients (with or without denture stomatitis of the palatal mucosa). Denture plaque was examined from 12 patients with complete dentures of unknown age. Clinical inspection of the palatal mucosa revealed that 5 suffered from denture stomatitis, while 7 exhibited a clinically normal palatal mucosa. Smears taken from the palatal mucosa and the fitting surface of the denture revealed the presence of bacteria in 11 of the 12 patients, while yeast cells were present in only 5, all of whom suffered from denture stomatitis. After the dentures were stained with a plaque disclosing solution, a 3 x 3 mm piece of the denture plate exhibiting plaque was cut out and processed for electron microscopy. Examination of sections in the light and electron microscope revealed no systematic differences between those from patients with denture stomatitis as compared with those with a clinically healthy palatal mucosa. In 2 specimens the denture was covered only by a very thin layer of condensed material which resembled the pellicle forming on teeth. In 10 the denture was covered with a deposit of microorganisms in an intermicrobial matrix. In 9 of these cocci or short rods predominated, and most of them were Gram-positive. In one specimen the plaque consisted of yeast cells only. The surface of the dentures was relatively smooth although minor irregularities were encountered. The denture material was in no instance invaded by microorganisms.

Bacteria↗
PubMed1979

Electron microscopic study of junctional and oral gingival epithelia in the juvenile and adult beagle dog.

A previous study demonstrated structural differences in the junctional epithelium between juvenile and adult dogs. In juveniles the junctional epithelium showed some resemblances to the oral gingival epithelium, and a cuticular structure at the dento-gingival junction was of particular interest. The oral gingival epithelium is considered to be less permeable than the junctional epithelium. As cytoplasmic filaments are held to be the main component in the process of keratinization, and to have a stabilizing influence on the cells and tissues, the present investigation was designed to study the relative amounts of cytoplasmic filaments in the junctional and the oral epithelia of beagle dogs during juvenile and adult stages. In addition, the ultrastructure of the dento-gingival junction was characterized. Six beagle dogs were used. The material consisted of gingival biopsies sampled when the dogs were 3 and 12 months old, respectively. On these occasions the gingiva was in excellent health. The biopsies were prepared for electron microscopic analysis and three randomly selected fields were recorded photographically from each of the following epithelial strata: basal and granular cell layers of the oral epithelium and basal and superficial cell layers of the junctional epithelium. Morphometric analysis was performed in order to estimate the density of cytoplasmic filaments of the cells in these epithelial strata. The amount of cytoplasmic filaments was considerably lower in the cells of the junctional epithelium than in those of the oral epithelium. In the oral epithelium the amount increased from basal towards superficial cells, whereas no such increase was seen in the junctional epithelium. The pattern was the same in the juvenile and the adult stage. At the dento-gingival junction all dogs had a thick, laminated layer of dental cuticle material in the juvenile stage. In the adult stage a similar structure was seen only infrequently, and it never attained the thickness observed in the juvenile stage.

Age Factors↗
PubMed1979

Surface ultrastructure of some oral bacteria.

Adhesion of Streptococcus sanguis, Fusobacterium nucleatum and an Actinomyces sp. to enamel and epon and their interspecies cohesion was studied with scanning and transmission electron microscopy. For adhesion studies enamel or epon was coated with salivary macromolecules and then cells of S. sanguis and in some experiments also with F. nucleatum or Actinomyces sp. Cells of S. sanguis were seen scattered over the surface of a thin "pellicle" that was heavily stained, and F. nucleatum and Actinomyces sp. adhered to S. sanguis or directly to the "pellicle". For studies of cohesion S. sanguis was brought to cohere with F. nucleatum or Actinomyces sp. and then processed for transmission electron microscopy. The morphology of the cell surface structures involved was studied in negatively stained preparations or in thin sections of material treated with ruthenium red or poststained with uranyl and lead salts, phosphotungstic acid or periodic acid-thiocarbohydrazide-osmium tetroxide. S. sanguis demonstrated a fuzzy coat of fimbriae that seemed to unfold in areas of contact with other cells, while cells of F. nucleatum had 6-10 polar pilus-like fimbriae, which appeared to be instrumental in cohesion, as did a dense coat of long, slender fimbriae that covered cells of Actinomyces sp.

Actinomyces↗
PubMed1977

Development of bacterial plaque in the oral cavity.

Dental plaque may be defined as bacterial aggregations upon the teeth and other solid structures inserted in the oral cavity. It is formed by oral microorganisms which attach to the teeth in sheltered areas along the gingival margin, on the approximal surfaces, and in pits and fissures on the masticatory surfaces. The plaque increases in quantity either by multiplication of already attached organisms, or by continuous addition to the deposits of bacteria from the saliva. Structural analyses indicate that the organisms are held together in an exracellular matrix partly produced by the organisms and partly derived from saliva. The microflora of plaque is complex and shows great individual variation. There are also characteristic differences in plaque from different sites on the teeth. Thus dento-gingival plaque is qualitatively different from that of the occlusal fissures. Furthermore, the relative proportion of different types of microorganisms may vary with the age of the deposit. Such information must be taken in consideration when attempts are made to develop chemical agents for the purpose of inhibiting plaque formation in order to prevent periodontal disease and caries.

Dental Plaque↗
PubMed1977

Microbial aggregate contamination of water lines in dental equipment and its control.

Water from some dental clinics has been examined and found to be discoloured, badly tasting and with a foul odour. Moreover, brown or black flakes were often present in tap water, as well as in the water lines of dental equipment. Examination by phase-contrast and electron microscope showed the flakes to consist of aggregated fungi and bacteria, and similar structures were found in a layer on the inner surfaces of the clinics water tubes and pipes. The ultrastructure of some aggregating microorganisms, including fungal hyphae and sheath-forming and stalked bacteria, was studied in detail, and several modes of aggregation were suggested. Cultivation of contaminated water samples revealed the presence of filamentous fungi, including Cladosporium and Cephalosporium, and of non-fluorescent Pseudomonas, Aeromonas, Acinetobacter, Alcaligenes, Flavobacterium, and Moraxella (?). Removal of microorganisms from the walls of the tubing was effectively accomplished by rinsing with the non-corrosive solution of 4 per cent Tween 80, coloured with Ponceau 4 R.

Bacteria↗
PubMed1975

Oral giant cell granulomas. An ultrastructural study of the vessels.

Eight peripheral and 2 central oral giant cell granulomas have been studied in the electron microscope in order to examine the structure and nature of the vessels. The vascular wall was composed of a continous layer of endothelial cells resting on a basal lamina, which was frequently multilayered. The lamina also surrounded scattered subjacent pericytes. The endothelial cells overlapped slightly so as to form narrow intercellular spaces. Based on these observations the vessels are supposed to be postcapillary venules. Dark cells exhibiting degenerative features were encountered in the endothelial lining of most vessels. Small gaps and larger defects in the vascular lining allowed direct continuity between the lumen and the perivascular tissue. It is suggested that the extreme extravasation of red blood cells frequently observed in oral giant cell granulomas may be mediated through this incomplete lining.

Blood Vessels↗