摘要:

The aim of this study was to investigate the ‘remineralizing potential’ in the mouth at certain intervals after a topical fluoride treatment. Remineralization was studied by microhardness measurements of slightly demineralized bovine enamel slabs. 4 dental students were given a topical acidulated phosphate fluoride (APF) treatment and 2, 4, 8 and 16 h after the treatment, 8 slabs were inserted and carried for 48 h. During the study, the subjects avoided other types of fluoride exposure. The statistical analysis of the microhardness changes showed a significant rehardening of the control slabs indicating remineralization from saliva. Slabs inserted 2–4 h after the fluoride treatment showed highly increased remineralization as compared to the controls, whereas those inserted 8 and 16 h after the treatment did not differ from the controls. The data are related to the fluoride concentration in saliva at various periods after APF treat

ISSN:0008-6568    

DOI:10.1159/000260536

出版商:S. Karger AG    

年代:1981

数据来源: Karger

摘要:

The aim of the present study was to examine the histopathological features of dental caries in fluorosed deciduous enamel and to compare these with caries in non-fluorosed deciduous teeth. Polarized light examination of ground sections from twelve teeth showed lesions of uniform pattern in the non-fluorosed material, but a more varied and complex picture in fluorosed tissue. The surface zone appeared wider in particular towards the occlusal part of the lesion. Within the lesions there was great variation in mineral loss with distinct ‘laminations

ISSN:0008-6568    

DOI:10.1159/000260537

出版商:S. Karger AG    

年代:1981

数据来源: Karger

摘要:

The diffusion of phosphate ions into whole bovine enamel at pH = 7 was investigated as a function of temperature, diffusion time and phosphate concentration. The results show the existence of a fast and slow diffusion process with activation energies of Ea = 0.5 ± 0.1 and 0.7 ± 0.1 eV, respectively. The diffusion mechanism is found to be independent of the phosphate concentrations in solution in the 0.5–5 mM range. The diffusion of the phosphate ions showed a time dependency in good agreement with Fisher’s grain boundary model. Taking into account the enamel ultrastructure, the results strongly indicate that phosphate is transported most likely interprismatically (fast process) as well as by a relatively slow diffusion process in which phosphate is transported between the individual enamel crystallites. The numerical values for the fast and slow diffusion process are: Dfast= (1.7 ± 1.2) × l0––12 cm2s––1 and Dslow= (5.7 ± 6.6) × 10––12cm2s––1. A comparison with calcium diffusion data from the literature show a same order of magnitude for D values and activation energies for the fast transport; the slow phosphate transport is several orders of magnitude lower than the slow calcium transport with an activation energy of abo

ISSN:0008-6568    

DOI:10.1159/000260538

出版商:S. Karger AG    

年代:1981

数据来源: Karger

摘要:

The diffusion of 32P–FPO32–– ions in whole bovine enamel from Na2FPO3 and radioactive tracer 32P–FPO32–– containing solutions was investigated at pH = 7.0 and 37 °C. Various diffusion times (2 and 7 days) and monofluorophosphate (FPO32––) concentrations (1 and 10 mM) were applied. Diffusion profiles have been obtained by the method of serial sectioning of the enamel. A diffusion coefficient Dk = (1.7 ± 0.4) × 10––13cm2s––1 for fast diffusion between the prisms and a diffusion coefficient Dv = (1.8 ± 0.6) × 10––18 cm2s––1 for slow diffusion into the prisms were calculated. The 32P-MFP diffusion profiles are different from similar profiles for phosphate ions, particularly for diffusion distances of less than 20 μm from the enamel surface. The diffusion coefficient for the fast diffusion of the MFP ion is about three orders of magnitude smaller than the diffusion coefficient for the fast diffusion of the fluoride ion. It is concluded that at neutral pH values MFP in enamel is transported in the form of FPO

ISSN:0008-6568    

DOI:10.1159/000260539

出版商:S. Karger AG    

年代:1981

数据来源: Karger

摘要:

Previous laboratory and animal studies have reported high levels of apatitic fluoride uptake from a topical fluoride procedure in which teeth were pretreated with an acidic solution saturated with respect to CaHPO4 • 2H2O (DCPD) prior to the fluoride treatment. A study was initiated to determine the fluoride uptake from this procedure under clinical conditions. A microbiopsy technique was used to measure enamel fluoride contents before, 1 month after, and 3 months after an application of an acidulated phosphate fluoride (APF) solution alone or in combination with a DCPD pretreatment on the maxillary incisors of 50 fourth-grade children in a nonfluoride area. 1 month after treatment, there was no significant difference in enamel fluoride concentration between APF and control groups. The DCPD/APF treatment produced mean fluoride uptakes of 1,011 ± 134 ppm (n = 50) and 2,042 ± 221 ppm (n = 47) in the outer 3.5 μm of enamel when measured 1 and 3 months, respectively, after treatment. The results indicate that the DCPD pretreatment can substantially increase permanently bound fluoride uptake under clinical condit

ISSN:0008-6568    

DOI:10.1159/000260540

出版商:S. Karger AG    

年代:1981

数据来源: Karger

摘要:

Artificial carious lesions were produced in human enamel using a diphosphonate/organíc acid system over periods up to 30 days, and progress assessed by depth measurement. Acids studied were lactic, acetic, propionic, isobutyric, succinic, tartaric, hydrochloric and hydrofluoric. The rate of lesion progress was found to be a function of calculated unionized acid concentration, and acid dissociation constant. Acetic acid made a major contribution to the rate of lesion formation, even at pH 5.0 or higher and is likely to be as important as lactic acid in the in vivo caries situation. Mixtures of acetic and lactic acid had additive demineralizing properties. This emphasizes the importance of acid type and concentration rather than pH alone

ISSN:0008-6568    

DOI:10.1159/000260541

出版商:S. Karger AG    

年代:1981

数据来源: Karger

摘要:

Measurement of fluoride concentrations in rat molars indicates that several areas of the dentition might be inaccessible to extraneous ions. In rats of all ages, much of the enamel, situated below the gingival margin, in occluded approximal regions or within the fissures might be unavailable to agents administered topically or otherwise. The paper discusses sampling the enamel surface of rat molars in the light of these findings.

ISSN:0008-6568    

DOI:10.1159/000260542

出版商:S. Karger AG    

年代:1981

数据来源: Karger

摘要:

A method is described for the preparation of caries-like lesions in human enamel using a short column of methyl cellulose gel to restrict demineralisation by lactate buffer. The procedure permits the analytical determination of the ions leaving the enamel. It is found that there is a preferential removal of calcium compared to phosphorus and this is interpreted in terms of a calcium-deficient hydroxyapatite system. The lesions produced show the apparently intact surface zone characteristic of the early carious lesion. Ground sections, when examined by polarised light, show a surface zone with 1–5% pore volume over a more extensively demineralised main body of the lesion. Only the dark zone was missing in sections examined after imbibition with quinolin

ISSN:0008-6568    

DOI:10.1159/000260543

出版商:S. Karger AG    

年代:1981

数据来源: Karger

摘要:

The concentrations of fluoride in the gingival crevicular fluid (GCF) of dog canines and carnassials were determined as a function of plasma fluoride levels using the filter paper strip technique. These were compared to the simultaneous concentrations of 131I 99mTc which were assumed to be markers for evaporative water loss of GCF. Plasma fluoride levels ranged from 15 to 300 μmol/l. The GCF to plasma fluoride concentration ratios at all plasma fluoride levels were consistently greater than unity. This was also true for the 131I and 99mTc GCF to plasma ratios. When the GCF to plasma fluoride ratios were factored by the radiotracer ratios, the values closely approximated unity. Thus, 131I and 99mTc appear to be valid markers for evaporative water loss of GCF. It is concluded that GCF fluoride levels are nearly identical to those of plasma over a wide range of plasma fluoride concentrations and that GCF is a source of fluoride for the oral environment

ISSN:0008-6568    

DOI:10.1159/000260544

出版商:S. Karger AG    

年代:1981

数据来源: Karger

摘要:

The ionic and total fluoride levels in pasteurised and untreated milk have been examined using a fluoride sensor. Ionic fluoride was determined in potassium nitrate and sodium citrate buffer solutions and total fluoride was determined after pyrohydrolysis or perchloric acid hydrolysis. Binding of added ionic fluoride to milk-calcium or milk-protein occurs after addition, making milk an unsatisfactory carrier of ionic fluoride.

ISSN:0008-6568    

DOI:10.1159/000260545

出版商:S. Karger AG    

年代:1981

数据来源: Karger