摘要:

Sound, human enamel slabs treated in vitro with (1) APF followed by SnF2, (2) DCPD followed by Basic Phosphate Fluoride (BPF) or (3) TiCl4 followed by APF were examined with the scanning electron microscope and electron microprobe prior to and after washing in an inorganic wash solution. APF/SnF2 deposited a dense, homogeneous coating which was resistant to washing. TiCI4 pretreatment resulted in enamel etching, and subsequent APF application resulted in a variable distribution of Ti and F. The deposited F appeared to be of a labile nature. DCPD pretreatment left the surface essentially intact, and BPF resulted in a uniform surface coating. Following the wash, the surface was covered with a lattice-like, crystalline network. These observations may help explain previous results regarding artificial caries-like lesion formation.

ISSN:0008-6568    

DOI:10.1159/000260707

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

Variations in acid dissolution and histological appearance of heated human tooth enamel due to temperature (100–600 °C) have been studied by means of chemical analyses, polarizing microscopy and scanning electron microscopy. The amount of dissolved Ca and the lesion depth obtained from the heated enamel after artificial caries-like lesion formation clearly vary dependent on the heating temperature and are closely related to the histological changes in enamel by heating. These variations are explained in terms of the permeability and the internal surface area of enamel. Laser effects on the acid dissolution of enamel are discuss

ISSN:0008-6568    

DOI:10.1159/000260708

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

Secondary ion mass spectrometry was used for determining the distribution of Na, K, Mg, Sr, F and Cl in the buccal enamel of human deciduous incisors. 16 teeth were analyzed. The samples were coated, by vapour deposition, with an aluminium grid, thus making it possible to produce two-dimensional contour maps of the elements. These contour maps were used to establish the distribution of elements throughout the enamel. The metallic elements except for Sr showed increasing concentrations towards the interior of the enamel. The halogens, in contrast, had higher concentrations at the surface and decreased towards the enamel-dentin junction. Sr showed a fairly even distribution throughout the enamel. No clean-cut differences in elemental distribution were seen between post- and prenatal enamel, although the postnatal enamel exhibited relatively wide variations for some elements

ISSN:0008-6568    

DOI:10.1159/000260709

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

The chemical systems to produce carious lesions described in the literature can be divided into three types: (a) gel systems, (b) systems containing a substance which decreases the dissolution rate of the mineral in the surface area of tooth enamel and (c) buffer systems containing calcium and phosphate. The third system can give essential information in the physicochemical sense, if in vivo conditions are simulated. This system was investigated in the present study. Artificial lesions were produced in the buccal surface of human premolars by applying buffers of pH 4 or 5 and which were undersaturated with respect to hydroxylapatite. Microradiographical tracings were taken from the sections and the following characteristics were studied: (a) the mineral content in the surface layer; (b) the mineral content of the body of the lesion; (c) and (d) the depth at which these mineral levels were reached, and (e) the depth of the lesion. It appeared that the mineral content in the surface layer decreased with decreasing degree of saturation and stabilized with time after an initial demineralization. The lowest mineral content of the body of the lesion decreased with decreasing degree of saturation and reached a final level close to zero. The speed with which the demineralization front progressed increased With decreasing degree of saturation of the buffer. The results are in agreement with the concept that the mineral in tooth enamel shows a gradient in its apparent solubility product with depth.

ISSN:0008-6568    

DOI:10.1159/000260710

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

In vitro enamel demineralization was studied in undersaturated calcium phosphate solutions containing fluoride in the concentration range 0–10 ppm. Depending on the fluoride concentration either erosion, white spot formation or complete protection of the enamel occurred. With the calcium and phosphate concentrations studied (2.2 mM) 2 ppm F was sufficient at pH 4.5 to effectively inhibit demineralization. In comparing calcium loss measured by microradiography and chemical analysis, good agreement was found between these two technique

ISSN:0008-6568    

DOI:10.1159/000260711

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

The uptake and retention of alkali-soluble and alkali-insoluble (fluorapatite) fluoride in human teeth in vivo was investigated in a group of orthodontic patients from whom two premolars were to be extracted. Daily mouthrinses with 0.05 % NaF for 2 weeks increased the fluoride content of the outer enamel layer (≈ 5 μm) by 15.9%. One rinse with 0.2% NaFincreased the fluoride content by 5.8%. Amajor part of the fluoride deposited was soluble in alkali. No significant uptake of fluoride in a second enamel layer (≈5 μm) was found. It is suggested that the alkali-soluble fraction of fluoride, representing the major part of the fluoride retentate, might serve as a significant reservoir of fluoride, and is perhaps a factor of prime importants concerning its cariostatic e

ISSN:0008-6568    

DOI:10.1159/000260712

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

Several different liquid diets have been proposed to use in tests to determine the cariogenic potential of foods fed to rats. A rat model has been developed to determine the cariogenic potential of foods. This entails feeding animals their essential nutrition in liquid form by means of gastric intubation and the test food on a programmed feeder. Several liquid diets of different nutritional density have been proposed for use in this test. Animals fed either of two of the four diets alone failed to survive the experimental period. It was further observed that the cariogenicity of a cookie fed through a programmed feeder was not affected by the liquid diets administered to the animals. The liquid diets were also without affect on the cariogenicity of diet 2000 fed ad libitum.

ISSN:0008-6568    

DOI:10.1159/000260713

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

The natural history of Streptococcus mutans was studied in occlusal fissures of 238 right and 235 left lower mandibular first molars in 279 children, initially aged 6–7, over a 2-year period. S. mutans infection was endemic in this group. Results showed that the levels of S. mutans were fairly stable – an initially high level of infection tended to stay high, and vice versa. High levels of infection were more associated with subsequent development of caries. None of the 21 teeth with nondetectable levels of S. mutans developed caries, though a number of teeth with high levels of S. mutans remained sound. S. sanguis appeared to have no independent influence on whether caries developed or

ISSN:0008-6568    

DOI:10.1159/000260714

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

Plaque and saliva samples were obtained from 55 children aged 13–15 years: 23 of them were caries free (group N) while the other 32 had evidence of high-caries activity over the preceding 2 years, with a mean DMFS of 25.9 (group H). The average concentration of calcium in posterior plaque of children in group N was 3.57 μg/mg (dry weight), compared with 1.63 μg/mg for group H. The average concentration of calcium in anterior plaque was 11.55 μg/mg in group N and 2.57 μg/mg in group H. The differences between groups N and H were statistically significant (p < 0.01). Similar significant differences were found between phosphorus levels in plaque. Although the mean levels of both calcium and phosphorus in saliva were higher for group N than for group H, only for phosphorus did the difference reach statistical significance (p < 0.05). The present study therefore shows that levels of both calcium and phosphorus are significantly higher in plaque taken from children with no caries experience than they are in plaque from children who are caries suscep

ISSN:0008-6568    

DOI:10.1159/000260715

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

It was shown that addition of 2% sodium lauryl sulphate to a 3% aqueous solution of sodium monofluorophosphate reduced the caries-inhibiting potential of the monofluorophosphate solution significantly, when this solution was applied topically at fortnightly intervals. It is suggested that this may be due to enzyme inhibition by the lauryl sulphate, denaturing bacterial enzymes in the oral cavity which would otherwise release free fluoride from the monofluorophosphate molecule. Almost all commercial toothpaste with sodium monofluorophosphate contains high amounts of sodium lauryl sulphate. It is suggested that this may impair the clinical effect of these toothpastes.

ISSN:0008-6568    

DOI:10.1159/000260716

出版商:S. Karger AG    

年代:1983

数据来源: Karger