Bacterial interference in vitro. Comparison between a quantitative kinetic and a cocultivation blood agar test method.

The aim of the present study was to compare two methods for estimation of bacterial growth interference between various bacteria using a Bioscreen robot analyzer, allowing kinetic documentation, and a cocultivation test on blood agar plates. Six laboratory strains with different virulence and growth requirements were used: Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Fusobacterium nucleatum, Streptococcus mitis, Staphylococcus aureus, and Staphylococcus epidermidis. The interference activity was correlated with a reference system of Streptococcus sanguis (strain alpha 89) and Streptococcus pyogenes (group A streptococci, GAS serotypes T 9 and T 22). The methods used and results obtained were as follows: 1. Estimation of synergistic and antagonistic bacterial interferences using a Bioscreen robot analyzer. Suspensions of viable bacteria were added to microtiter plates with different concentrations of UV light-killed bacteria in liquid media. The Bioscreen analyzer monitored bacterial growth every 10 min for 24 h giving kinetic data during the growth period. Synergisms as well as antagonisms were demonstrated between the tested bacterial strains which have not earlier been reported in the literature. However, the antagonistic effect observed between the six strains was less than that induced by the S. sanguis strain on the two strains of S. pyogenes. 2. Cocultivation of bacterial strains on blood agar surface with precultivated or simultaneously stamped interfering bacteria indicated no detectable interference between the six tested bacterial strains, while the S. sanguis strain inhibited the growth of S. pyogenes strains as well as the hemolysis around the colonies. The Bioscreen method was found more sensitive for testing bacterial interference compared to the commonly used blood agar test.

The interference of gingival cell cultures with growth of selected bacteria.

The aim of the present study was to analyze the interference of oral tissue cells or cell lines (effector cells) with growth of reference bacteria, and furthermore to investigate whether cells derived from different individuals differ in such activity. The reference bacteria were Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus mitis, Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, and Fusobacterium nucleatum. The effector cells used were gingival fibroblasts (GF) from 21 periodontally involved persons, gingival epithelial cells (E) from 2 such persons, HeLa cells (HeLa), and an amnion cell line (Amnion). The cells were cultivated and their supernatants tested for antibacterial activity in a Bioscreen robot analyzer (Labsystems, Finland). Results suggest that the antibacterial activity of each tested primary cell line of tissue had its own profile depending on cell type and donor, and that the composition of oral microbiota was influenced by oral cells, which might, in turn, contribute to the variations in the pathogenesis of periodontal diseases.

Connective tissue response to periodontal dressing.

The effects of three periodontal dressings (Coe-Pak, PPC, Perio Putty) upon subcutaneous tissues in 26 Sprague-Dawley rats were investigated. The three dressings, and a control (Teflon), were placed into polyethylene tubes. Two tubes per animal were implanted on either side of the dorsal midline area. After 14 days the specimens were retrieved and prepared for histological examination. Three methods of scoring were utilized for evaluation. First, a system evaluating the overall number of inflammatory cells, connective tissue capsule thickness, and the vascular changes produced; second, an inflammatory cell count, the Inflammatory Index (I.I), computing the inflammatory cells in a particular field of view for each material; and third, a Reaction Spread Index (R.S.I.) comparing the distance of the spread of the inflammatory reaction into the connective tissues. Statistical analysis of the data was carried out utilizing the Chi-square test and analysis of variance. While the three scoring systems utilized did result in some comparative variation in reactions, the overall order of decreasing severity was always PPC, Coe-Pak, Perio Putty, and Teflon.

Scanning electron microscopy of the root surface texture of extracted periodontally diseased teeth following various etching and chelating regimens.

Scanning electron microscopy of root surfaces that had been ultrasonically scaled and subjected to various conditioning regimens revealed the presence of two distinct types of cracks: extensive cracks, presumed to have been caused by drying before and during sputter-coating procedures; and smaller cracks that reflected the pattern of the irregular underlying dentin. Both etching and chelating agents appear to cause demineralization of the interfacial layer between cementum and dentin, causing a "peeling off" of cementum and exposure of the underlying dentin. The results suggest that burnishing the scaled root surface with either saline or any of the etching or chelating agents for at least 10 seconds, followed by soaking the cementum in 8% ethylenediaminetetraacetic acid for about 40 seconds, achieved a root surface that might be regarded as optimal for regeneration of periodontal tissues.

Plaque removal by dental floss or toothpicks. An intra-individual comparative study.

The amount of plaque accumulation was assessed in an intraindividual study comprising 10 individuals. During different 2-week periods, the test subjects used nylon floss (unwaxed, waxed and specially treated), silk floss (unwaxed and waxed), Superfloss or triangular toothpicks for interdental tooth cleaning. Only teeth in contact with neighboring ones and with open interdental spaces were included in the study. The plaque removal of the interdental aids used was registered by estimating the amount of plaque present at the end of each experimental period according to a Plaque Index (Silness & Löe 1964) modified for plaque registration on 10 surface units around each tooth. In general, dental floss had a higher plaque removing potential than triangular toothpicks, especially on lingual axial surfaces.

Efficacy of plaque-removal using interdental brushes and waxed dental floss.

The plaque-removing efficacy when using waxed dental floss and three interdental brushes was compared in an intraindividual clinical trial. Nine adult patients treated for periodontal disease, with a reduced but healthy periodontium and large interdental spaces were subjects in the study. Each subject tested the four interdental cleaning aids in random sequence over a 2-wk period. The duration of the study was 8 wk. The results indicated that the use of interdental brushes is preferable to that of dental floss in cleaning interdental areas where the papilla is missing. No difference in achieved cleanliness was noted after use of the different interdental brushes tested. No gingival damage or damage to the hard tissue of the teeth was observed after use of interdental brushes or dental floss.

Craniomandibular disorders in adult populations of West Bothnia, Sweden.

A randomly selected sample of 1992 adults (995 men and 997 women) representing four equally sized age groups of 25-, 35-, 50-, and 65-years-old inhabitants of West Bothnia were studied for prevalence of symptoms and clinical signs of mandibular dysfunction. Of the sample 79% completed a questionnaire and a clinical examination. The chewing inability increased with age. Recurrent headaches (once a week or more often) were reported to occur in 11% to 15% of the four age groups, and the duration of headaches was generally more than 2 years. Tooth-clenching, which was the most frequent oral parafunction, was reported significantly more often in women, whereas attrition was more severe in men. The commonest clinical finding was temporomandibular joint clicking, which varied between 13% and 35% in the different age groups. Crepitation was observed more often in women and increased with age. The jaw muscles were more frequently tender to palpation in women and the elderly. The mean maximal mouth opening capacity varied between 55 mm and 44 mm, decreasing with age, and was for the whole sample significantly higher among men. Since signs and symptoms of craniomandibular disorders were common findings in all age groups, routine dental examination should always include functional evaluation of the stomatognathic system.

Calf anticular cartilage in organ culture in a chemically defined medium. I. Autoradiographic study after [35S]sulfate labeling.

Articular cartilage from 5-month-old calves survived for 4 weeks in organ culture in a chemically defined medium. The viability was assessed by calculating the labeling frequency of chondrocytes on autoradiograms after [35S]sulfate labeling. The survival rate of chondrocytes was highest in 20% oxygen tension, whereas 50% oxygen resulted in chondrocyte death after 2 weeks. The survival rate was improved by using 1-mm thick standardized pieces of cartilage. The cells of the superficial layer showed a higher proportion of living chondrocytes than the cells in the deeper layers. No differentiation, dedifferentiation, or outgrowth of cells occurred during the experimental period.

Oral manifestations in Urbach--Wiethe disease (lipoglycoproteinosis; lipoid proteinosis; hyalinosis cutis et mucosae).

The oral manifestations in 27 patients with Urbach--Wiethe disease (UWD) discovered in Northern Sweden are described. The oral regions most frequently affected are the lips, the back of the tongue, the frenulum of the tongue, the palate and the back wall of the pharynx. The general impression is that older patients usually have more marked manifestations than younger, indicating that the oral lesions may become more severe with increasing age. Histopathologically, the disorder is essentially a microangiopathy in which the walls of small blood vessels are thick and PAS-positive, indicating the presence of glycoproteins. In clinically affected regions there are usually PAS-positive extravascular deposits. In material used of lipid histochemical studies, sudanophil droplets were found in the vessel walls. By staining with osmium tetroxide the osmium is--contrary to previous assumptions--in some way bound to the droplets, but for unknown reasons is not reduced to a coloured product. The binding of osmium was demonstrated by the OTAN (osmium textroxide alpha-naphthylamine) method. The exact significance of this finding awaits further studies. The implications of dental anomalies occurring in UWD are discussed.

Scanning electron microscopy of palatal mucosa maintained in organ culture: a method for three-dimensional visualization of cell morphology.

A scanning electron microscopic (SEM) study of palatal mucosa maintained in organ culture (50% O2-Eagle's MEM w/o serum) from 12 to 360 hours is presented. The morphological changes occurring in the explants during culture are illustrated and the findings are compared with those observed using transmission electron microscopy and light microscopy. The results confirm that cellular fine structure in epithelium and connective tissue is more easily visualized when SEM is employed following in vitro maintenance of explants as opposed to examination of fresh uncultured biopsies. The in vitro system used would appear to be applicable to studies designed to investigate the effect of various substances on cell proliferation and cell interactions.

Cytotoxicity in bacterial cultures: interaction and cell-specificity, possible factors in periodontal disease.

Cytotoxicity in culture media of various growing bacterial strains was estimated by Cr-51 release of labelled target-cells. Interaction studies were made by adding each of the different UV-killed bacteria to the medium with viable bacteria. The reference oral bacterial strains were: Actinobacillus actinomycetemcomitans Y4, Porphyromonas gingivalis, Fusobacterium nucleatum and Streptococcus mitis, which were compared with the reference bacteria Staphylococcus aureus 209 and Staphylococcus epidermidis. The target cells were: gingival fibroblasts (GF), periodontal membrane fibroblasts (PMF), pulpal fibroblasts (PF), HeLa-cells (HeLa), and lymphoid neoplasm cells (LN). Synergistic, as well as antagonistic, effects on target cells were observed. The cytotoxicity of A. actinomycetemcomitans in presence of P. gingivalis is neutralized while in presence of S. aureus it was increased. Bacterial interactions with F. nucleatum and P. gingivalis cytotoxicity were observed. The cytotoxicity of F. nucleatum was increased when cultured together with A. actinomycetemcomitans. Each cell type reacted differently to the toxicity of the supernatant of growth medium in which the same bacterial strain had been cultivated, which indicates cell specificity of the toxins.