摘要:

Dextran-glucosidase EC 3.2.1.70 isolated from Streptococcus mitis ATCC 903 was tested for activity on water-soluble polysaccharides produced from sucrose by four Streptococcus mutans strains: AHT, BHT, IB and B13. Two fractions of glucans with molecular weights of about 40,000 and < 9,400 were obtained by gel filtration of water-soluble glucans of S. mutans. The elution profiles were essentially the same for the four strains. Upon incubation of these glucans with dextran-glucosidase, only 10–30% of the low-molecular weight glucans remained. The high-molecular weight glucans were resistant to dextran-glucosidase or were degraded to 25%. Glucose was the degradation product. The yields of water-soluble polysaccharides from the S. mutans strains varied between 17.6 mg/ml culture supernatant (IB) to 1.4 mg/ml (B13

ISSN:0008-6568    

DOI:10.1159/000260995

出版商:S. Karger AG    

年代:1987

数据来源: Karger

摘要:

In one experimental series, 19 rats were fed a nutritionally adequate diet (20% protein) and 19 rats a protein-deficient diet (5% protein). After 18 days, pilocarpine/isoproterenol-stimulated saliva was collected. Saliva from the protein-deficient rats had a lower protein concentration and bacteria agglutinating activity. Calcium concentration was increased. No difference in secretion rate was observed. In another experimental series, 14 rats were given the adequate diet and 14 rats the protein-deficient diet. To enhance biosynthesis in the secretory cells the cells were emptied by an injection of pilocarpine. 1 h later, 14C-glucosamine (UL) was given. After another 2-hour period and after a second stimulation with pilocarpine, saliva was collected. The saliva samples containing radiolabelled glycoproteins were incubated with a serotype c strain of Streptococcus mutans at 37 °C for 30 min to adsorb labelled glycoproteins from the saliva. The total counts in the saliva samples from the two dietary groups were similar, but saliva from the deficient rats contained a lower amount of labelled glycoproteins adsorbable to the bacteria. We conclude that the total amount of glycoprotein synthetized during the experimental 2-hour period is not changed whereas the synthesis of biologically active agglutinin is decreased

ISSN:0008-6568    

DOI:10.1159/000260996

出版商:S. Karger AG    

年代:1987

数据来源: Karger

摘要:

In this article a new microradiographic approach for measuring the mineral content after various demineralization stages of the same enamel section and of the same area is described. Repositioning errors are smaller than 3 μm. The method described uses thick sections (up to 300 μm can be used). The error in mineral content is of the same order (3% by volume) for thick sections as for thin sections. The experiments with this method showed that the first stage in demineralization is a surface-softening process; later on a surface layer was observed. A linear least-square fit of the cube of the lesion depths found shows a high correlation (r = 0.99). This is also valid for the cube of the microhardness indentation lengths made perpendicular to the surface (r = 0.96). The results described in this study indicate that the new microradiographic method is suitable for repeated measurements of mineral distribution

ISSN:0008-6568    

DOI:10.1159/000260997

出版商:S. Karger AG    

年代:1987

数据来源: Karger

摘要:

The fluoridating efficiencies of five fluoridated toothpastes have previously been studied in an in vivo model. The aim of this study was to correlate fluoride uptake in partially demineralized enamel with the volume of toothpaste used. The amounts of free ionic fluoride, fluoride as MFP and total fluoride delivered by the toothpastes were evaluated and correlated with the observed fluoride uptake in the enamel. Substantial differences between participants were discovered in the volumes of toothpaste used. However, for any given participant a relatively small variation was found in the amount of toothpaste used between the various pastes tested. A positive correlation was found between the amount of toothpaste used and the corresponding fluoride uptake. Furthermore, the levels of free ionic fluoride and MFP in the toothpastes linearly correlated with the fluoride uptake. On the other hand no such correlation was observed for the amount of total fluoride.

ISSN:0008-6568    

DOI:10.1159/000260998

出版商:S. Karger AG    

年代:1987

数据来源: Karger

摘要:

This paper reports measurements of oral retention and intra-oral distribution of triclosan in man after use of an antiplaque toothpaste slurry containing this antibacterial. Determinations of triclosan were made by high-performance liquid chromatography. It was shown that 38% of the triclosan in a 1-gramme dose of toothpaste (0.50%, w/w triclosan) and 62% of a 3-gramme dose was retained. Triclosan was detected and measured in plaque and this antibacterial was also present in saliva. Levels of approximately 20–30 μg triclosan/ml of saliva were measured 5 min after toothpaste use and these had fallen to approximately 3–4 μg/ml 2 h later. A significant inhibition of plaque acid production is shown to follow use of the antiplaque denti

ISSN:0008-6568    

DOI:10.1159/000260999

出版商:S. Karger AG    

年代:1987

数据来源: Karger

ISSN:0008-6568    

DOI:10.1159/000261000

出版商:S. Karger AG    

年代:1987

数据来源: Karger

ISSN:0008-6568    

DOI:10.1159/000261001

出版商:S. Karger AG    

年代:1987

数据来源: Karger

摘要:

Morphological aspects of dentinal caries in rats are described. Carious lesions on free dentinal lingual surfaces of lower first and second molars developed after: (i) removing the enamel layer by offering rats 0.1 M lactic acid as drinking water from day 20 to day 30; (ii) infecting the animals in relative gnotobiosis with Actinomyces viscosus OMZ 105E, Streptococcus mutans OMZ 176E and Lactobacillus acidophilus OMZ 3E in a complete factorial arrangement; (iii) feeding the rats a sucrose-rich cariogenic diet to the end of the experiment on day 94. The tissues from 2 animals of each group comprising 12 animals each were fixed by perfusion. The dissected jaws from these animals were decalcified in EDTA and further processed for light and electron microscopy. Material from the remaining decapitated animals was used for scanning electron microscopy and for the preparation of nondecalcified sections. The lactic acid treatment produced distinct dentinal windows. On day 30, the exposed dentin was practically unchanged with respect to density and structure of collagen and matrix. Only animals infected with A. viscosus alone or in combination with S. mutans and/or L. acidophilus produced dentinal carious lesions during the following caries test period which were morphologically characterized. Because of the close similarity between coronal and root dentin with respect to composition and structure, this animal model seems to be a valid approach to study the various aspects of root caries.

ISSN:0008-6568    

DOI:10.1159/000261002

出版商:S. Karger AG    

年代:1987

数据来源: Karger

摘要:

Caries scores were examined in rats being fed a high sucrose diet and inoculated with Streptococcus mutans (strain No. 6715) in order to determine if addition of NH4F to the drinking water would afford the same caries protection as addition of NaF. Sixty rats were divided into six groups. Group I received distilled water, II NaF, and III NH4F. Groups IV and V received NaF or NH4F with Na- or NH4-phosphate, respectively, while group VI received NH4-phosphate alone. The F concentration was 30 ppm. The PO4 concentration was equimolar with that of F (1.6 mM). All solutions were prepared at pH 7. Another 60 rats were similarly treated except that all solutions contained 0.2% sucrose and 16 mM acetic acid adjusted to pH 5 with NaOH. The mean caries scores ( ± SD) in the pH 7 series were for group I 55 ± 23, II 17 ± 24, III 5 ± 6, IV 7 ± 9, V 9 ± 22 and VI 43 ± 19. The corresponding caries scores in the pH 5 series were for group I 37 ± 24, II 15 ± 17, III 6 ± 6, IV 6 ± 5, V 1 ± 1 and VI 59 ± 27, respectively. NaF and NH4F were equally caries-protective at pH 7 irrespective of the presence of PO4. At pH 5, NH4F was more protective than NaF, with or without PO4. Addition of PO4 to either NH4F or NaF resulted in increased caries protection. The best protection was afforded by NH4F with or

ISSN:0008-6568    

DOI:10.1159/000261003

出版商:S. Karger AG    

年代:1987

数据来源: Karger

摘要:

Enamel biopsies for F analysis were performed on the mesial, buccal, distal and lingual surfaces of contralateral pairs of premolars extracted from 104 10- to 14-year-old children. Five successive etchings, each of 5 s duration, were carried out on the mesial and buccal surfaces with 2 M HClO4, and 5 successive etchings, each of 2 s duration, were performed on the distal and lingual surfaces using 0.5 M HClO4. The F concentrations were adjusted to standardized depths and the F concentrations at individual and cumulative etch depths determined. The caries experience of the children was expressed as filled teeth (FT) or filled surfaces (FS). Highly significant correlations (p = 0.0001) between age and FT and FS were obtained. No significant relationship between dental caries experience and enamel F concentration was established in the present study except for a significant correlation between dental caries and the enamel F concentration in the outermost 10 μm on the buccal aspects of the premolar teeth

ISSN:0008-6568    

DOI:10.1159/000261004

出版商:S. Karger AG    

年代:1987

数据来源: Karger