摘要:

Studies were conducted to gain insights into how remineralization by fluorapatite (FAP) deposition onto hydroxyapatite (HAP) crystals might influence dissolution rate behavior and acid resistance. Dissolution rate behavior of compressed pellets was studied in 0.1 M acetate buffer, pH 4.5, ionic strength 0.5, using the rotating disk method. Attempts were made to determine the dissolution rate controlling phase by addition of common ions (Ca, P, F) to the buffer solution. Preliminary studies on HAP pellets and almost pure FAP pellets showed that FAP dissolved appreciable slower than HAP under the conditions used. The specific ion effects on FAP dissolution were consistent with predictions based on the expected ionic activity product of this mineral. The dissolution rate behavior of FAP-HAP mixtures in acid without common ions present in the buffer solution were interpreted as follows. With pellets prepared from HAP crystals onto which FAP had been precipitated, the first dissolving phase was FAP even at the lowest concentration of this phase. With pellets of mechanically mixed FAP and HAP the two components dissolved relatively independently. The reduced dissolution rates of FAP mineralized HAP compared with the mechanically mixed case and particularly with pellets of pure HAP may be of clinical significance. It is suggested that deposition of fairly low levels of FAP during in vivo remineralization may significantly decrease the tendency for caries formation.

ISSN:0008-6568    

DOI:10.1159/000260679

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

Remineralization patterns and F profiles in remineralized bovine enamel subjected to prior demineralization have been studied using a new acid-abrasion procedure. These data were then compared to those obtained from the perchloric acid-etch procedure employed in our laboratories and the data obtained by the previously reported abrasion (without acid) procedure. All three of the procedures (namely acid-abrasion, abrasion and acid-etch) gave reasonably close F profiles, remineralization patterns and cumulative 45Ca/F ratios in the enamel samples remineralized at a pKFAP of 108. The newly developed acid-abrasion procedure is much more satisfactory than the relatively tedious abrasion (without acid) method, especially when enamel analyzed up to depths as great as 50–100 μm are involv

ISSN:0008-6568    

DOI:10.1159/000260680

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

The in vitro incorporation of non-KOH extractable fluoride into human enamel during a topical application of potassium fluoride and after 24 and 96 h incubation was studied with and without surface-active agents (SAA) in the solutions. The SAA included Lodyne S-110, Zonyl FSC, Zwittergent 310 and 316, dodecylamine-HCl and sodium dodecyl sulfate. Incorporation of Lodyne S-110 and Zonyl FSC into the fluoride solutions effected increased deposition of fluoride in enamel already during the application. All SAA effected increased deposition of fluoride in specimens incubated for 24 h after application. Presence of SAA did not enhance fluoride deposition in specimens incubated for 96 h after application. The findings are consistent with the view that the presence of SAA in fluoride solutions for topical therapy can increase the deposition of firmly bound fluoride in the enamel and that this increase is achieved by affecting the kinetics of enamel fluoride interactions.

ISSN:0008-6568    

DOI:10.1159/000260681

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

The rentention of copper and zinc in dental plaque in vivo after repeated mouth rinses with aqueous solutions of salts of these elements was measured by neutron activation analysis. The reduction in acidogenicity of plaque after exposure to the metal ions was also monitored. A significant reduction (p < 0.05) in acid formation was seen in plaque exposed to five subsequent rinses. The mean amounts of Cu and Zn in plaque increased more than 10-fold after five rinses. It is concluded that these metals are retained in plaque and that their concentrations in plaque increase with repeated applications.

ISSN:0008-6568    

DOI:10.1159/000260682

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

The retention and behaviour of fluoride contained in plaque and underlying enamel has been studied in the artificial mouth. Artificial plaque was grown either on bovine enamel or on platinum foil. At 6-, 18- and 48-hour intervals, after a final application of NaF solution (200 ppm F- twice a day for 10 min, on 3 days) the plaque and 5 superficial enamel layers were analyzed for F––. After 6 h, plaque grown on enamel contained 226 ppm. After 12 h, the concentration was 158 ppm and after 48 h 70 ppm. The respective data for plaque on platinum foil were 212, 90 and 36 ppm. In plaque-covered enamel the fluoride concentration decreased in the outer layers with time, but not in cleaned enamel. It is concluded that under cariogenic conditions a considerable amount of the fluoride in plaque was derived from the underlying ena

ISSN:0008-6568    

DOI:10.1159/000260683

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

The rate of sugar clearance from the mouth would seem to be an important parameter in caries susceptibility. Such clearance is by dilution with saliva and periodic swallowing. A mathematical model of this process has been developed which incorporates a variable salivary flow rate dependent on salivary sugar concentration and in which swallowing is treated as an incomplete syphon. The parameters in the model include the amount of sugar in the mouth at time zero (S), the unstimulated salivary flow rate, the maximum sugar-stimulated flow rate, the delay between taste stimulation and development of a steady stimulated flow rate, the taste theshold for sugar, the sugar concentration in a saturated solution, the volume of saliva in the mouth initially and the volume in the mouth before swallowing (VMAX) and immediately after swallowing (RESID). The most important parameters affecting clearance appear to be the unstimulated salivary flow rate and the volumes of saliva in the mouth immediately before and after swallowing. Surprisingly, the value of S was of lesser importance, mainly because as S increased, so did the stimulated flow rate which increased the rate of clearance. This result is in keeping with the finding of the Vipeholm study that increasing the amount of nonretentive forms of carbohydrate in the diet had minimal effects on caries. The model is of value for assessing the relative importance of the various parameters affecting clearance and may help to account for differences in caries susceptibility between individuals with apparently similar intakes of carbohydrates. This study appears to be the first to identify the importance of RESID and VMAX in salivary sugar clearance.

ISSN:0008-6568    

DOI:10.1159/000260684

出版商:S. Karger AG    

年代:1983

数据来源: Karger

ISSN:0008-6568    

DOI:10.1159/000260685

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

As a consequence of the partial substitution of sucrose by sugar alcohols in the cariogenic diets 580 or 2000, rats often suffer severe diarrhoea, resulting in retarded body weight gains, impaired general health and sometimes high mortality. The purpose of the present study was to develop a more suitable diet to test sugar substitutes, with special emphasis on the general health of the rats and less extreme caries scores in comparison to diet 2000. A purified powder diet (SSP), which meets the nutritional requirements of the rat and containing 50% carbohydrates in which the ratios of starch, sugars and sugar substitutes can be varied, was tested. The results showed that: (1) Streptococcus mutans established well in the oral cavity of the rats; (2) this diet induced reproducible and moderate numbers of carious fissure lesions in S. mutans inoculated rats while non-inoculated animals remain almost caries free; (3) polyols can be added to this diet within reasonable limits without inducing diarrhoea and without influencing body weight gains and general health. In addition it was shown that the partial substitution of starch by xylitol resulted in a statistically significant caries reduction (p < 0.02), both in S. mutans serotype c and serotype d inoculated rats.

ISSN:0008-6568    

DOI:10.1159/000260686

出版商:S. Karger AG    

年代:1983

数据来源: Karger

ISSN:0008-6568    

DOI:10.1159/000260687

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

Enamel was exposed to diphosphonate solutions (EHDP) in vitro and in vivo. EHDP inhibited remineralization in vitro, but increased the resistance against acid when incorporated in the enamel. In vivo EHDP acted differently. This may be explained by additivity of the effect of EHDP on acid formation in plaque and the effect of surface active salivary molecules to the inhibition of EHDP on de- and remineralization as was found in the in vitro experiments.

ISSN:0008-6568    

DOI:10.1159/000260688

出版商:S. Karger AG    

年代:1983

数据来源: Karger