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Biomedical subjects

E Theilade

Publications and source records attributed to E Theilade.

At least 19 recordsLinked to original sources
PubMed1994

Population structure of Actinobacillus actinomycetemcomitans: a framework for studies of disease-associated properties.

The Actinobacillus actinomycetemcomitans population consists of a large number of clones among which the ubiquitous leukotoxin gene operon appears very homogeneous. Population genetic analyses performed by multilocus enzyme electrophoresis together with DNA fingerprinting and analyses of genomic DNA restriction fragment length polymorphisms (RFLP) on 97 strains isolated over a period of 45 years revealed that each of the serotypes a, b, c, d and e comprise genetically isolated subpopulations and that successful horizontal transfer of genomic DNA between strains of different serotypes appears to be extremely rare in vivo. In contrast, recombination between strains of the same serotype in general appears to take place in nature. The results provide evidence that non-serotypeable strains are serotype antigen-deficient variants originating from strains of the known serotypes. Serotype b and c strains may contain transmittable DNA sequences not found in strains of the other serotypes.

Actinobacillus Infections↗
PubMed1994

Effect of local metronidazole application on periodontal healing following guided tissue regeneration. Microbiological findings.

The bacteriological colonization of healing periodontal defects was investigated after treatment with guided tissue regeneration using expanded polytetrafluoroethylene membranes together with local metronidazole gel (25%, 250 mg/g). Twelve patients, each with one pair of comparable defects, had the test defect treated with the membrane plus metronidazole gel and the control defect treated with the membrane alone. Thirty weeks after removal of the membrane, the median gain in probing attachment level as a percentage of the initial defect depth was 92% for the test defects and 50% for the control defects (P = 0.001). The median number of cultivable bacteria decreased from 1.2 x 10(6) at the presurgical examination to 3.0 x 10(5) at the one week examination in the test group (P = 0.02), whereas an increase was observed in the control group. Similarly, a lower median proportion of black-pigmented Gram-negative anaerobic rods was observed one week postsurgically in the test group (0.004%) compared to the control group (3.5%) (P = 0.02). Two weeks after membrane insertion, and at all following examinations, no microbiological differences between test and control group were observed. Consequently, the influence of the metronidazole gel on the treatment result appears to have been confined to the initial regeneration phase. Despite the good clinical results in the test group, all membranes from both test and control pockets were heavily colonized with bacteria at the time of removal. To ensure maximal periodontal regeneration with formation of bone, future research in this area should concentrate on reducing the microbial colonization of the wound area.

Administration, Topical↗
PubMed1993

Microbiology of the pericoronal pouch in mandibular third molar pericoronitis.

The microorganisms associated with mandibular third molar pericoronitis were investigated using direct microscopy and anaerobic culture method. The pericoronal pouch was sampled with paper points in A) 8 patients without mandibular third molar pericoronitis and B) 6 patients with mandibular third molar pericoronitis. Under the microscope, the microflora was found to be a complex mixture comprising gram-positive and gram-negative cocci, rods and filaments (including fusiform and curved rods), motile rods and spirochetes. Significantly higher proportions of motile, gram-negative rods were found in group B than in group A. The predominant cultivable microflora of 9 samples: A (4) and B (5) comprised several species of facultative and obligate anaerobic bacteria, namely Peptostreptococcus, Streptococcus, Actinomyces, Eubacterium, Propionibacterium, Veillonella, Porphyromonas, Prevotella, Bacteriodes, Fusobacterium, Campylobacter, Staphylococcus, Stomatococcus, Lactobacillus, Neisseria, Capnocytophaga, Haemophilus, Selenomonas and Centipeda species. The microflora in pericoronitis appeared similar to that of diseased periodontal pockets.

Adolescent↗
PubMed1989

Advances in oral microbiology.

More than 200 species of micro-organisms have been identified in the resident oral microflora colonizing teeth and oral mucosa. Their numbers and proportions are regulated by several ecological mechanisms such as antimicrobial factors in saliva and gingival fluid, intermicrobial synergism and antagonism, host diet, etc. Due to their pathogenic potential, oral micro-organisms cause dental caries, periodontal disease, mixed anaerobic infections of oral tissues, and sometimes infections in other organs. The role of specific bacteria or virulence factors in plaque-induced diseases is difficult to assess because of the microbial complexity and variability of dental plaque. Correlations have been established between Streptococcus mutans, lactobacilli and dental caries, and also between spirochaetes, certain Gram-negative rods and periodontal inflammation. The predictive value of microbiological tests as indicators of active caries or periodontal destruction is, however, too low to justify clinical use. Preventive methods such as plaque control and sugar restriction help establish a microflora compatible with oral health.

Humans↗
PubMed1986

The non-specific theory in microbial etiology of inflammatory periodontal diseases.

In the absence of toothbrushing, the gingival crevice is colonized by a complex indigenous microflora causing gingivitis, a non-specific inflammation. Subgingival plaque may develop by downgrowth into the inflamed pocket of those micro-organisms from supragingival plaque which can multiply there. By direct microscopy, increased proportions of motile rods and spirochetes have been found in diseased pockets. Cultures on selective media have demonstrated increased prevalence of various gram-negative rods. Cultures on non-selective media have revealed the complexity and variability of the subgingival microflora, comprising more than 200 species. Destructive periodontitis is the result of subgingival colonization, which is favored by such ecological changes as plaque accumulation, gingivitis, and gingival exudate. These changes increase the numbers of micro-organisms and alter their proportions, but no single species appears in active sites which is not also commonly present in inactive sites. The subgingival micro-organisms have several virulence factors which promote colonization of the pockets, destroy host defense mechanisms, and provoke inflammation. It appears that different combinations of indigenous bacteria, rather than just a single species, can produce the pathogenic potential necessary to cause progression from gingivitis to destructive periodontitis.

Bacterial Physiological Phenomena↗
PubMed1985

Validity of a dietary interviewing method for use in caries prevention.

A suitable method for determining the usual diet of an individual is a prerequisite for dietary counseling in caries prevention. The purpose of this study was to develop a method that was able to obtain relevant information on the dietary habits of an individual and to test the validity of this method. During a series of interviews a dietary history interview was therefore developed with special emphasis on dietary factors known to be important in caries etiology, such as frequency of eating and frequency and duration of sugar intake at meals and in-between meals. The validity of the method with regard to caries-related factors was tested by interviewing 49 caries-active and 55 caries-inactive 14-yr-old Danish schoolchildren. It was possible to detect a higher frequency of food intake and a more frequent and long-lasting use of sugar in the caries-active group. No difference was found in the consumption of sticky sugars between the two groups. With the present method it should be possible to pinpoint dietary problems in caries-active persons, so that dietary advice can be given in quantitative terms.

Adolescent↗
PubMed1985

Formation and ecology of plaque at different locations in the mouth.

Some recent findings concerning microbial colonization of smooth surfaces of teeth, gingival crevices, occlusal fissures and removable dentures are reviewed considering the many ecologic factors of importance for the oral microbial communities. The oral microbiota is extremely complex comprising at least 200 taxa. In spite of interindividual and site-to-site variations, each oral habitat has a characteristic microbiota ranging from Gram-positive, facultatively anaerobic cocci and rods in occlusal fissures to predominance of Gram-negative, strictly anaerobic rods and spirochetes in deep periodontal pockets.

Dental Plaque↗
PubMed1983

Predominant cultivable microflora of plaque on removable dentures in patients with healthy oral mucosa.

Plaque from the fitting surface of upper full dentures in eight patients with healthy palatal mucosa was studied. To characterize the predominant cultivable flora, 916 isolates (100-128 from each sample) were subcultured from anaerobic roll-tubes. Streptococci constituted 0-81 per cent (median, 41 per cent) of the isolates with varying proportions of Streptococcus milleri, Streptoccus mutans, Streptococcus salivarius, Streptococcus mitior and Streptococcus sanguis. Staphylococcus aureus made up 0-13 per cent (median, 6 per cent). Gram-positive rods constituted 1-74 per cent (median, 33 per cent). Among these, Actinomyces israelii, Actinomyces naeslundii, Actinomyces viscosus and Actinomyces odontolyticus were the most common species, whereas lactobacilli were isolated only from two samples, constituting 21 and 48 per cent. Among Gram-negative bacteria, only Veillonella parvula was common, constituting 3-20 per cent (median, 10 per cent). Gram-negative rods were isolated only from three samples in small proportions making up 0-6 per cent (median, 0 per cent) of the flora. Forty-seven isolates (5 per cent) were lost. Cultures for yeasts on Sabouraud agar were positive for five samples and the yeast counts corresponded to 0-0.45 per cent (median, 0.002 per cent) of the total viable counts. The microflora of denture plaque is highly variable and is to a large extent similar to that of some forms of dental plaque.

Actinomyces↗
PubMed1983

Quantitative relationship between yeast and bacteria in denture-induced stomatitis.

Quantitative cultural studies of yeasts and bacteria were made from 7-day-old denture plaque accumulate on pieces of self-adhesive tape stuck on the fitting surface of the maxillary denture in 17 edentulous subjects with healthy oral mucosa and in 27 patients affected with denture-induced stomatitis. Significantly higher numbers of yeasts and bacteria were cultured in the stomatitis patients than in the controls. This indicates that the rate of plaque formation is increased in patients with denture-induced stomatitis. Yeasts usually constituted less than 1% of the anaerobic bacterial counts, but the percentage of yeasts was significantly higher in the stomatitis patients than in the controls. There was a significant correlation between initially higher yeast counts and improvement of the clinical condition of the palatal mucosa following antimycotic treatment. In some patients only bacteria were grown and antimycotic treatment had no effect. The study supported the contention that yeast antigens and toxins of denture plaque are significant factors in initiation and maintenance of denture-induced stomatitis. However, bacteria may also be involved as pathogens.

Aged↗
PubMed1983

Regional variations in viable bacterial and yeast counts of 1-week-old denture plaque in denture-induced stomatitis.

Quantitative cultural studies of yeasts and bacteria were made from 1-week-old denture plaque accumulated on pieces of self-adhesive tape stuck on the fitting surface of the maxillary denture in four well-defined locations. A tape piece was also stuck on the buccal denture flange. The cultural examinations were made in 15 patients with denture-induced stomatitis which affected most of the denture-bearing mucosa. There was no significant difference of the bacterial counts from the different sampling areas although the variations between patients was significant. The yeast counts from the test area located on the buccal denture flange were significantly lower than those originating from the fitting denture surface. On the other hand, there was no significant variation of the yeast counts when comparing the test areas of the fitting denture surface. In 12/15 of the patients yeast counts of greater than or equal to 10(3)/cm2 were obtained from the fitting denture surface. The results indicate that the environmental conditions beneath a denture base predispose for yeast colonization and are different from those present on the buccal flange.

Bacteria↗