摘要:

This paper gives a detailed description of the development of the surface layer during demineralization of human enamel. Optical inspection of microradiograms of lesions in different stages of development can give the impression that the surface layer increases in thickness with time. Using a more objective method of inspection together with an explicit description, the development of the surface layer was followed with time more quantitatively. This method was based on the changes occurring at the inside of the surface layer. It appeared that the surface layer thickness was constant with time in all lesions investigated. These observations indicate that at constant composition of the buffer solutions, no dissolved material from the body of the lesion is deposited at the inside of the surface layer.

ISSN:0008-6568    

DOI:10.1159/000260756

出版商:S. Karger AG    

年代:1984

数据来源: Karger

摘要:

A mouth rinse containing calcium, phosphate, fluoride, urea and monofluorophosphate was used 12 times over 3 days by 15 young adults. The concentration of acid-extractable fluoride in 4-day-old plaque rose from 8.4 to 560 ng/mg dry weight. Plaque calcium increased from 4.1 to 42.5 μg/mg and phosphate from 3.9 to 22.7 μg/ mg. The ions are fixed in a form insoluble in saliva, probably as fluorhydroxyapatite, and thus are likely to have an extended caries-protective effec

ISSN:0008-6568    

DOI:10.1159/000260757

出版商:S. Karger AG    

年代:1984

数据来源: Karger

摘要:

The effects of F+ Mg additives on the F varnish-treated bovine enamel underneath a fermenting Streptococcus mutans layer was investigated. The enamel slabs with the streptococcal layer were incubated at 37 °C for 18 h. The final pH after the fermentation on the highly fluoridated enamel surface was 4.4, whereas the added fluoride concentration of 25 ppm elevated the final pH by 0.5 unit. Added magnesium had no effect on pH values. Magnesium was released from the cells during the sucrose fermentation and the fluoride addition prevented this release by one half, whereas the magnesium addition had no effect. The fermentative dissolution of Ca from the enamel was decreased by the added fluoride while the phosphorus dissolution was not significantly altered. The added fluoride further increased the enamel fluoride content but could only slightly prevent the enamel softening caused by the preceding etching and by fermentation of the streptococcal layer. The addition of magnesium had a slight tendency to reduce all the enamel-protective effects of fluoride

ISSN:0008-6568    

DOI:10.1159/000260758

出版商:S. Karger AG    

年代:1984

数据来源: Karger

摘要:

The concentration of fructose, glucose and sucrose, the pH and the titratable amount of acid were analyzed in the following groups of soft drinks (8–11 samples per group): (1) fruit juices, (2) fruit drinks, (3) carbonated beverages and (4) sport drinks. Moreover, the effect of representative products on pH changes of dental plaque was studied in two groups of teenagers with 16 or 19 subjects per group. The fruit juices, fruit drinks and carbonated beverages contained, on average, a total amount of sugars (fructose + glucose + sucrose) of 9.3–9.8%. The corresponding value for sport drinks was 4.4%. The sucrose content was high in 1-week-old fruit drinks and carbonated beverages, but decreased, by spontaneous hydrolysis, to relatively low values when stored at room temperature for 5 months. The mean pH values in the various soft drinks varied between 3.1 and 3.6. Fruit juices had the highest titratable amount of acid, approximately 2–3 times higher than the three other groups of products. Mouth rinses with orange juice, orange drink and Coca-Cola® resulted in low and about the same plaque pH. The sport drinks (Gatorade® and Pripps Pluss®) induced also low plaque pH values but somewhat less than the other products (p < 0.01). When Coca-Cola was consumed either from a glass or with a straw, the pH decrease was significantly smaller compared to a mouth rinse with the same product (p < 0.001). To conclude, the results from the present investigation indicate that commonly used soft drinks, i.e. fruit juices, fruit drinks, carbonated beverages and sport drinks, have about the same ‘cariogenicity’ as far as the total amount of sugars, acidity and the effect on plaque pH a

ISSN:0008-6568    

DOI:10.1159/000260759

出版商:S. Karger AG    

年代:1984

数据来源: Karger

摘要:

Rats, orally inoculated with Streptococcus mutans OMZ 176 and Actinomyces viscosus Ny-1, received 18 meals daily of either sucrose, cooked wheat starch or a 1:1 mixture of sucrose and cooked wheat starch. Meals were offered for 10 min with either a 30-min interval between the 18 consecutive meals, or in three blocks of 6 meals offered without interval (0 min) within each block. With a 0-min interval between meals, the 1:1 mixture was most cariogenic and cooked wheat starch the least. A 30-min interval between meals resulted in a significant increase in cariogenicity for all test diets. The largest absolute increase was in the 1:1 mixture group, the largest relative increase was in the cooked wheat starch group. The results appear to be related to the oral clearance time of the test foods in rats and the effect of prolonged contact time of fermentable carbohydrate on plaque pH.

ISSN:0008-6568    

DOI:10.1159/000260760

出版商:S. Karger AG    

年代:1984

数据来源: Karger

摘要:

A cariostatic effect of copper sulfate was observed in rats in a recent study by Afseth et al. In the present study, effects of the combination of topically applied copper with fluoride in the drinking water were determined. Groups of animals receiving a combination of copper and fluoride developed significantly less caries than the groups given either substance alone at the corresponding concentrations. Reduced numbers of Streptococcus mutans were isolated from animals receiving Cu treatment. This reduction was most pronounced in rats treated with elevated Cu concentrations alone and in combination with F.

ISSN:0008-6568    

DOI:10.1159/000260761

出版商:S. Karger AG    

年代:1984

数据来源: Karger

摘要:

The relationship between mineral loss in approximal enamel and the precision of the radiographic diagnosis was investigated using experimental lesions and Receiver Operating Characteristic (ROC) technique. The ROC curves indicated a substantial loss of radiographic information concerning the presence or absence of a lesion when mineral loss was reduced from 10 to 5%, but the diagnoses were better than pure guessing. Variations in horizontal angulation within a range of 25 ° did not affect detection, but lesion depth was overestimated more often at eccentric projections. The results indicate that radiographic diagnosis is unreliable for small carious lesions with about 5% mineral loss in the X-ray beam direction, and that positive diagnosis is frequently due to observer error

ISSN:0008-6568    

DOI:10.1159/000260762

出版商:S. Karger AG    

年代:1984

数据来源: Karger

ISSN:0008-6568    

DOI:10.1159/000260763

出版商:S. Karger AG    

年代:1984

数据来源: Karger

ISSN:0008-6568    

DOI:10.1159/000260764

出版商:S. Karger AG    

年代:1984

数据来源: Karger