摘要:

After de- and subsequent remineralization at 0.03 and 1.0 ppm fluoride and either 0, 1, 10, 20 or 25 mM carbonate, artificial lesions in bovine enamel were demineralized again. The amount of secondary demineralization was determined after 15,30 and 70 h of demineralization by means of quantitative microradiography. The results showed that fluoride incorporated during the remineralization period retards lesion formation during secondary demineralization. Carbonate incorporated during the remineralization period enhances secondary demineralization. An interaction between both ions was observed.

ISSN:0008-6568    

DOI:10.1159/000261417

出版商:S. Karger AG    

年代:1992

数据来源: Karger

摘要:

Subsurface lesions in bovine enamel slices were remineralized. The remineralization solutions contained either 0.03,0.3, or 1.0 ppm fluoride at either pH 5.5 or 6.8. The amount of remineralization was determined after periods of up to 610 h, using quantitative microradiography. The results showed that after 126 h of remineralization in the presence of 0.03 ppm fluoride significantly (p < 0.05) more remineralization occurred at pH 6.8 than at pH 5.5. At 0.3 and 1.0 ppm fluoride no significant differences between pH 5.5 and pH 6.8 were observed. An interaction between fluoride and pH was observed. The observed differences in the rates of remineralization are explained by the formation and subsequent transformation of the precursors octacalcium phosphate (pH 6.8) and brushite (pH 5.5) into (fluor)apatites.

ISSN:0008-6568    

DOI:10.1159/000261418

出版商:S. Karger AG    

年代:1992

数据来源: Karger

摘要:

A rapid and flexible model system has been developed to study human enamel behaviour under conditions of oscillating pH similar to those experienced in the mouth. The model uses realistic time intervals and operates at in vivo temperatures (35–37 °C). Mineral loss or gain is measured quantitatively on a volume basis. Results indicate that for single 1-day periods with three 20-min exposures to acid, 1 % v/v of enamel mineral was lost. These results, together with the histological appearance of the tissue, are in close agreement with previous studies of enamel cari

ISSN:0008-6568    

DOI:10.1159/000261419

出版商:S. Karger AG    

年代:1992

数据来源: Karger

摘要:

In this paper, data are presented on the in situ demineralization of human enamel as a function of the demineralization period. To quantify the mineral loss parameters versus time, it is important to obtain information on the kinetics, and thus on the mechanism of dental caries. The results show that for in situ enamel demineralization, the lesion depth as well as the mineral loss parameter both vary linearly with the demineralization time. This is in contrast to in vitro lesion formation where the third power, or the square power of the lesion depth is linearly related to the demineralization time. In in situ demineralization, the rate-determining step of the demineralization process is the inhibitor-controlled dissolution process at the enamel crystallite surfaces, while the inhibitor content (F––, proteins etc.) in the lesion originating from the plaque, saliva and enamel is high. Furthermore, the study indicates that in in situ demineralization, interprismatic mineral loss is very import

ISSN:0008-6568    

DOI:10.1159/000261420

出版商:S. Karger AG    

年代:1992

数据来源: Karger

摘要:

Ion adsorption and ion exchange are two methods commonly used in small home units to treat drinking water to bring the fluoride concentration to within acceptable limits. However, the necessary flowthrough system is often difficult to arrange where there is no piped supply and gradual exhaustion of the active agent is not easily detected. In an attempt to overcome these problems a defluoridation method based on the precipitation of a sparingly soluble fluoride salt, fluorapatite, has been studied. Samples of simulated high-fluoride drinking waters, approximately 10 ppm F, were saturated with brushite, resulting in a state of supersaturation with respect to fluorapatite. Subsequent seeding with hydroxyapatite caused a lowering of the calcium, phosphate, and fluoride concentrations in solution, indicative of fluorapatite precipitation. Repeating the process had an additive effect. Bone char was a less effective seed than hydroxyapatite with water containing fluoride only, but was a more effective seed with simulated Kenyan borehole water containing additional salts. Sixty-minute brushite saturation and apatite seeding steps were generally more effective than 10-min steps. The results suggest that apatite coprecipitation may be a convenient low-technology way to defluoridate drinking water, although prior testing might be useful to ensure adequate removal of fluoride.

ISSN:0008-6568    

DOI:10.1159/000261421

出版商:S. Karger AG    

年代:1992

数据来源: Karger

摘要:

Fluoride analyses of baby foods were carried out using a microdiffusion technique, which was found to be reproducible and accurate with less than 8% error. Analysis of 113 baby foods and drinks showed a wide range of fluoride concentrations: 0.01–0.31 mg F/kg for baby milk products; 0.04–0.72 mg F/kg for meat products; 0.04–0.70 mg F/kg for cereals; 0.03–0.48 mg F/kg for vegetable products; 0.03–0.07 mg F/kg for fruits; 0.02–0.28 mg F/kg for desserts, and 0.01–0.51 mg F/l for baby drinks. None of the baby foods and drinks contained fluoride of a sufficiently high concentration to be of concern or likely to contribute to enamel mottling, when used in t

ISSN:0008-6568    

DOI:10.1159/000261423

出版商:S. Karger AG    

年代:1992

数据来源: Karger

摘要:

The effect of maltitol on caries development was examined in an experimental caries system employing specific pathogen-free (SPF) Sprague-Dawley rats. Fourteen strains of oral streptococci, including mutans streptococci, did not utilize the maltitol nor produce sufficient acid to demineralize tooth enamel. Furthermore, maltitol did not serve as a substrate for glucosyltransferases of either Streptococcus mutans MT8148R or Streptococcus sobrinus 6715 to synthesize water-insoluble glucan. Maltitol induced no significant dental caries in SPF rats infected with these mutans streptococci, and replacement of the dietary sucrose content with maltitol resulted in a trend towards caries reduction in SPF rats.

ISSN:0008-6568    

DOI:10.1159/000261424

出版商:S. Karger AG    

年代:1992

数据来源: Karger

摘要:

Chronic protein-energy malnutrition during the period of growth and development causes permanent disturbances of salivary gland function and tooth structure. Moderate protein-energy deficiency also causes impaired saliva secretion rate and composition in the adult rat. These impairments have been shown to coincide with an increased incidence of dental caries. In the present investigation we studied the effect of chronic malnutrition on saliva secretion rate and susceptibility to dental caries in Indian children. It was found that chronic malnutrition reduced the secretion rate of stimulated saliva, but not that of unstimulated saliva. The salivary buffer capacity was continuously decreased as the secretion rate decreased with the level of malnutrition in the Indian children. The malnourished children developed increased caries. Thus, it could be concluded that chronic malnutrition in growing children enhances the cariogenic potential stemming from fermentable carbohydrates

ISSN:0008-6568    

DOI:10.1159/000261425

出版商:S. Karger AG    

年代:1992

数据来源: Karger

摘要:

The aim of this study was to assess the applicability of palladium touch micro-electrodes, connected to battery-run pH meters, for in vivo plaque pH measurements in children. The pH was assessed in 20 7-year-old and in 19 14-year-old caries-active and caries-inactive rural Kenyan children. The resting pH was measured at non-carious interproximal and occlusal sites and in open dentine cavities. Independent repeated measurements were performed at given sites at intervals of 15 s and 5 min and on different days. The resting plaque pH varied widely among the children, and there was no significant difference between caries-active and caries-inactive groups. The most striking feature was the considerable erratic fluctuations of pH at a given site with time, both in resting and in sucrose-challenged plaque. These fluctuations were sensitively recorded by palladium touch microelectrodes. After a sucrose rinse, not all sites in the same mouth behaved in a similar fashion, and thus the classical ‘Stephan curve’ was not always apparent. In conclusion, the palladium touch microelectrodes are highly applicable for plaque pH measurements in children, even under extreme field conditi

ISSN:0008-6568    

DOI:10.1159/000261426

出版商:S. Karger AG    

年代:1992

数据来源: Karger

ISSN:0008-6568    

DOI:10.1159/000261427

出版商:S. Karger AG    

年代:1992

数据来源: Karger