摘要:

Cells from a number of isolated strains of oral streptococci have been shown to be sensitive to 1–10 ppm of fluoride (0.05–0.53 mM NaF). Inhibition of glucose utilization at pH 5.5 varied for different strains and was unrelated to the site of origin or the cariogenicity of the microorganisms. It is suggested that in vivo responses of plaque to low concentrations of fluoride may be dependent on the sensitivities of the constituent bacterial strains to the inhibi

ISSN:0008-6568    

DOI:10.1159/000260283

出版商:S. Karger AG    

年代:1977

数据来源: Karger

摘要:

A brief pretreatment of hydroxyapatite with 1 mM of fluoride caused a reduced uptake of the acidic protein albumin, whereas an increased uptake of the basic protein protamine was observed. Pretreatment with the cations calcium or aluminium had the opposite effect. It is suggested that surface adsorption of the ions in question and changed surface charge of the apatite may be the mechanism involved. The fluoride taken up by the hydroxyapatite during the pretreatment was to a large extent soluble in 1 M KOH, showing that only small amounts of fluoroapatite were formed. As no calcium fluoride could be have been precipitated during the experimental conditions used, an adsorption of fluoride to calcium sites on the surface or in the hydration shell of the hydroxyapatite is postulated.

ISSN:0008-6568    

DOI:10.1159/000260284

出版商:S. Karger AG    

年代:1977

数据来源: Karger

摘要:

Sound and artificially decalcified enamel has been studied by dynamic and static thermal analysis. Weight losses mainly due to water release occur in 3 temperature ranges: 20–150, 150–400 and 400–550 °C. Special attention has been given to water release occurring in the range 150–400 °C. Here the weight losses for sound and carious enamel are 1.9 ± 0.3 and 4.5 ± 0.9%, respectively. Possible models for HPO42–– and H2O incorporation are discussed. The experimental thermal analysis studies, combined with infrared and X-ray data indicate that the mineral phase in sound enamel and carious enamel can be approximated by the formulae of water-containing non-stoichiometric apatites. In the temperature range 150–400 °C, the (firmly bound) H2O content in sound and carious enamel is comparable. The significant difference in weight loss between sound and carious enamel is caused by the differences in HPO4

ISSN:0008-6568    

DOI:10.1159/000260285

出版商:S. Karger AG    

年代:1977

数据来源: Karger

摘要:

147 samples of whole human enamel were analyzed for Sr by spark source mass spectrometry. Each sample was from an individual of known caries history and a life-long resident of their community. Results showed a geographic variation in Sr concentrations with individual concentrations as high as 1,200 ppm. The highest mean concentrations were noted in teeth from N. W. Ohio. Comparisons of Sr levels in teeth of low caries individuals (DMFT 7) showed that high concentrations of Sr in enamel were associated with low caries.

ISSN:0008-6568    

DOI:10.1159/000260286

出版商:S. Karger AG    

年代:1977

数据来源: Karger

摘要:

The cultivable flora was examined in seven plaque samples collected from New Guinea indigenes with active radicular caries. The predominating organisms were streptococci. Actinomyces and related genera accounted for most of the remaining flora. Of 202 strains of gram-positive filamentous or diphtheroid organisms, 154 were presumptively identified as resembling either Actinomyces (126), Rothia dentocariosa (3), Propionibacterium (8), corynebacteria (3), Lactobacillus (12) or Bacillus (1). Strains of Actinomyces were classified as resembling A. viscosus (21), A. naeslundii (20), A. odontolyticus (40), A. israeli (41) or A. propionicus (4); A. odontolyticus was the only species isolated from all samples and was predominant in four samples.

ISSN:0008-6568    

DOI:10.1159/000260287

出版商:S. Karger AG    

年代:1977

数据来源: Karger

摘要:

The effect of ingesting boiled sweets (candies) supplemented with 3% dicalcium phosphate dihydrate on dental plaque composition was investigated in five separate studies. Regular exposure to the experimental sweets during the first 48 h of plaque formation was associated with higher calcium and inorganic phosphorus concentrations in plaque than similar exposure to the control sweets. However, no differences were apparent when ‘mature’ plaque from subjects consuming either experimental or control sweets for a period of 1 year was investigated. The effect on plaque composition of a single exposure to the experimental sweet was not significantly different from that of exposure to the control sweet in either 2-day plaque of young adults or ‘mature’ plaque of c

ISSN:0008-6568    

DOI:10.1159/000260288

出版商:S. Karger AG    

年代:1977

数据来源: Karger

ISSN:0008-6568    

DOI:10.1159/000260289

出版商:S. Karger AG    

年代:1977

数据来源: Karger

ISSN:0008-6568    

DOI:10.1159/000260290

出版商:S. Karger AG    

年代:1977

数据来源: Karger

ISSN:0008-6568    

DOI:10.1159/000260291

出版商:S. Karger AG    

年代:1977

数据来源: Karger

ISSN:0008-6568    

DOI:10.1159/000260292

出版商:S. Karger AG    

年代:1977

数据来源: Karger