摘要:

The influence of saliva on lactose-reversible adherence between strains of Actinomyces viscosus and Streptococcus sanguis or Streptococcus mitis was investigated. Because saliva agglutinated these organisms, it was necessary to develop models for studying streptococcal attachment to Actinomyces cells which did not depend upon mixed agglutination of both interacting organisms. One model involved the binding of radiolabelled streptococci to spermine-conjugated agarose beads coated with Actinomyces. This assay appeared to parallel previously described coaggregation reactions because coaggregation-positive streptococcal strains attached in much higher numbers to the Actinomyces-coated beads than did coaggregation-negative strains. Lactose and also saliva which had been depleted of streptococcal agglutinins strongly inhibited attachment of coaggregation-positive organisms. A second model involved use of sonic extracts of Actinomyces cells which agglutinated coaggregation-positive streptococcal strains, but not coaggregation-negative strains. This extract-induced streptococcal agglutination was also inhibited by lactose and by saliva samples collected from 6 donors representative of blood types A, B, and O.

ISSN:0008-6568    

DOI:10.1159/000260765

出版商:S. Karger AG    

年代:1984

数据来源: Karger

摘要:

Immunoglobulin A (IgA) protease, a family of bacterial enzymes, cleaves human IgA1 at a single bond generating distinct Fab and Fc fragments. Purified secretory IgA with known specificity for Streptococcus mutans NCTC 10449 (serotype c) was hydrolyzed with IgA protease prepared from Streptococcus sanguis ATCC 10556. The isolated Fab fragments retained their initial activity by specifically binding to antigen and by deterring the sucrose-dependent adherence of S. mutans to glass indicating that the antigen-binding fragments behave as immunologically competent elements.

ISSN:0008-6568    

DOI:10.1159/000260766

出版商:S. Karger AG    

年代:1984

数据来源: Karger

摘要:

The dentition of humans and rats was treated with a short-term, high-dose application of chlorhexidine. This strongly suppressed the indigenous microflora on the teeth. At different time intervals after chlorhexidine application, a dominant member of the human plaque microflora, Actinomyces viscosus, was inoculated to investigate the effect of the retained chlorhexidine on its establishment. It was found that until 72 h after chlorhexidine application the initial colonization of the molar teeth of rats by A. viscosus Ny1S was affected by the retained chlorhexidine. In humans A. viscosus Ut3SR colonized the oral cavity better after chlorhexidine application than after professional cleaning. Under these conditions, however, the inoculated A. viscosus Ut3SR still made up only 0.1–1% of the total A. viscosus/naeslundii population on the teeth. Inoculation of humans with an unlabeled A. viscosus strain, isolated from their own oral cavity, did not contribute to the reestablishment of the indigenous A. viscosus/naeslundii population after chlorhexidine treatmen

ISSN:0008-6568    

DOI:10.1159/000260767

出版商:S. Karger AG    

年代:1984

数据来源: Karger

摘要:

Aqueous extracts, 1% (w/v), of Nigerian chewing sticks derived from the African plants Serindeia warnecki, Prosopsis africana, Pseudocedrela kotschyi, and Anoigeissus schrimperi were found to effectively inhibit the attachment of S. mutans 6715wt13 to glass or saliva-coated hydroxy-apatite beads. It was shown that the active compounds in these extracts interfere with binding of the bacteria, resulting in reduced adherence. Although no large effect upon the total extracellular glucan synthesis was noted, there was a 15% reduction in the water-insoluble polysaccharide synthesis. Chemical and spectral analysis of the active constituent from S. warnecki showed this material to have the characteristics of a high molecular weight polyphenolic tannin. 1% aqueous solution of tannic acid was also shown to promote similar in vitro adherence inhibition as the tannin-like substance from S. warnecki. In conclusion, the results imply that chewing stick constituents appear to play an important role in restricting plaque accumulation and caries incidence.

ISSN:0008-6568    

DOI:10.1159/000260768

出版商:S. Karger AG    

年代:1984

数据来源: Karger

摘要:

A laboratory artificial caries technique has been used to compare the susceptibility of ‘young’ and ‘old’ enamel to an identical acid attack. Results showed that the lesions in old enamel were more demineralized than those in young enamel. A well-defined surface zone was usually absent in the old specimens, and furthermore the old enamel was obviously thinner than the young enamel. Fluoride analysis of the outer 80 μm of enamel showed young enamel to be richer in fluoride than old enamel, but still the old enamel exhibited a minor concentration gradient. The results indicate that old enamel should not necessarily be regarded as more resistant to acid attack than youn

ISSN:0008-6568    

DOI:10.1159/000260769

出版商:S. Karger AG    

年代:1984

数据来源: Karger

摘要:

A means of bringing porous mineralised tissues within the scope of the acid-etching technique in vitro is described. The addition of dye to the solution used in acid-etching procedures is strongly recommended to ensure that the etching solution does not penetrate beyond the intended sampling zone.

ISSN:0008-6568    

DOI:10.1159/000260770

出版商:S. Karger AG    

年代:1984

数据来源: Karger

摘要:

Point count analyses were made with the electron microprobe for Ca, Na and Mg in a vertical cross-section through the enamel of a freshly erupted human pre-molar in the approximal area. A low excitation energy was chosen to limit the size of the excited volume and to suppress the evaporation of Na. The Na content showed variations with a wavelength of 6 ± 1 μm, which equals the distance of cross-striations. The Mg content showed variations with a wavelength of 25 ± 4 μm which equals the distance of striae of Retzius, whereby these striae probably contain a higher Mg content. On the assumption that higher Na and/or Mg contents represent mineral with a higher solubility, the observed variations in mineral composition help to explain the fine structure of carious lesions as observed frequently by microscopy and microradiogra

ISSN:0008-6568    

DOI:10.1159/000260771

出版商:S. Karger AG    

年代:1984

数据来源: Karger

摘要:

Secondary ion mass spectrometry (SIMS) was used for determining the concentrations of Na, K, Mg, Sr, F and Cl in human deciduous enamel from three groups of children. From infants with a birth weight less than 2,000 g, 11 teeth were analyzed. 4 teeth from infants with congenital hypothyroidism were analyzed and as references 16 teeth from normal healthy full-term infants were used. It was shown that normal deciduous enamel displayed differences in elemental distribution between pre- and postnatal enamel, differences between the inner and outer parts of the enamel and certain correlations between the recorded elements. In the enamel from infants with perinatal disorders the low birth weight groups appeared more similar to the normals than the hypothyroid group, which differed from the other groups.

ISSN:0008-6568    

DOI:10.1159/000260772

出版商:S. Karger AG    

年代:1984

数据来源: Karger

摘要:

Class V cavities were prepared at the cemento-enamel junction on the facial surfaces of 45 extracted human central maxillary incisors. Enamel samples for analysis were obtained by means of perchloric acid etching from circular areas, 1 mm in diameter, positioned 1.5, 3.5, 5.5, and 7.5 mm from the incisal and apical margins of the restorations, respectively. The preparations were filled with Fuji Ionomer Restorative, Type II. The restored teeth were individually suspended in synthetic saliva at 37 °C and the saliva changed at regular intervals. 15 teeth were removed after 1, 3, and 6 months, respectively. Enamel and cementum samples were again obtained from the teeth from sites parallel and adjacent to the previous biopsy sites. The fluoride content of the etching solutions was determined by gas chromatography and the calcium content by atomic absorption spectrophotometry. Fluoride acquired by enamel after 1 month ( ± 2,500 ppm F) was retained after 3 and 6 months. Fluoride acquired by cementum after 1 month ( ± 15,000 ppm F) was significantly reduced after 3 months ( ± 6,000 ppm F) and maintained at this level after 6 mon

ISSN:0008-6568    

DOI:10.1159/000260773

出版商:S. Karger AG    

年代:1984

数据来源: Karger

摘要:

Inorganic pyrophosphatase activity was quantitated in hard and soft dentine from sound and carious human teeth. The activity was measured from samples of dentine drilled from four to six different areas of 1 tooth. In intact fully formed tooth the highest rate of hydrolysis of Na4P2O7 was found in coronal and apical circumpulpal dentine. The highest PPiase activity in hard dentine (8.23 μmol/min and mg protein × 10––7) was observed in coronal circumpulpal dentine of tooth with caries reaching the dentine. In amalgam-restored tooth the values were nearly the same as in intact fully formed tooth. In tooth with caries advanced into the pulp cavity, the pigmented hard dentine gave significantly higher values (6.62 μmol) when compared with the same area of intact tooth (3.90 μmol). In more superficial areas with soft and infected carious dentine the activity was four times higher (27.61 μmol) than in pigmented dentine. The results suggest that the activity of PPiase in hard circumpulpal dentine reflects the increased metabolic activity during tooth development and during the advance of caries in dentine. In soft carious dentine, the high PPiase activity was thought to be caused by bacteria invading the injure

ISSN:0008-6568    

DOI:10.1159/000260774

出版商:S. Karger AG    

年代:1984

数据来源: Karger