摘要:

Formic acid was the most prominent acid in resting plaque. The mean acid concentrations for formic, acetic, lactic and propionic acids were 8.18, 5.75, 1.66 and 0.4 nmol/mg wet weight, respectively. There were no statistically significant differences between the acid content of plaques from molars and anterior teeth nor between buccal and lingual sites.

ISSN:0008-6568    

DOI:10.1159/000260913

出版商:S. Karger AG    

年代:1986

数据来源: Karger

摘要:

The effects of five different intense sweeteners on the growth and metabolism of mixed cultures of dental plaque microorganisms or a pure culture of Streptococcus mutans NCTC 10449 were studied (a) in peptone liquid media, (b) in agar media by the zone inhibition method and (c) in tryptone soya medium by a modification of the minimum inhibitory concentration method. Acesulfam-K and cyclamate showed no activity. The effect of Talin was obscured by its tendency to precipitate from solution. Only aspartame and saccharin had any inhibitory action, with aspartame the more effective in the mixed plaque cultures and saccharin the more effective against S. mutans.

ISSN:0008-6568    

DOI:10.1159/000260914

出版商:S. Karger AG    

年代:1986

数据来源: Karger

摘要:

Inorganic phosphate was determined by the reduction of a phosphomolybdate complex with ascorbic acid or stannous chloride. Fluoride interfered with both methods: (i) Absorbance of the complex reduced by ascorbic acid decreased slowly after incubation with fluoride concentrations higher than 5 μM (0.01 ppm). When a large number of samples had to be handled it was difficult to control the influence of fluoride because after a certain time has elapsed between reduction of the complex and reading of the sample there was a decrease in absorbance. (ii) The complex reduced by stannous chloride also showed interference at fluoride concentrations higher than 0.5 μM (0.01 ppm). In this case the interference of fluoride was found to be predictable for a known F–– content. The presence of proteins caused precipitation problems with the ascorbic acid method whereas the stannous chloride method was less sensitive when proteins were pr

ISSN:0008-6568    

DOI:10.1159/000260915

出版商:S. Karger AG    

年代:1986

数据来源: Karger

摘要:

In this study evidence is provided for the existence of a gradient in solubility and rate of dissolution of human tooth enamel. These gradients were obtained quantitatively by applying calcium and phosphate-containing acetate buffers of varying degree of saturation with respect to hydroxyapatite on transversely abraded enamel. It could not be ascertained to which extent the gradient in the rate of dissolution is due to thermodynamic or geometrical factors. A minimum value of the rate constant of dissolution was estimated from the experimental results.

ISSN:0008-6568    

DOI:10.1159/000260916

出版商:S. Karger AG    

年代:1986

数据来源: Karger

摘要:

Little is known about very early structural changes in human enamel during carious attacks. For this reason a scanning electron microscope study was conducted on discrete artificial lesions created under chemically controlled conditions using a lactate buffer system for up to 4 weeks. The loss of calcium and phosphorus varied extensively from specimen to specimen. About 7μg or more calcium had to dissolve from a 1.77-mm2 area to produce a white spot lesion. It was not possible to distinguish in the scanning electron microscope between control and experimental areas. Any structural changes induced by this simulation of a very early caries attack were masked by developmental variations and imperfections. This variability necessitates standardisation on selected tooth surfaces

ISSN:0008-6568    

DOI:10.1159/000260917

出版商:S. Karger AG    

年代:1986

数据来源: Karger

摘要:

Artificial caries-like lesions of enamel were subjected to each of the following treatments: storage in deionized water, fluoride application, heating and exposure to a calcifying fluid, and then reexposure to an artificial caries system. After reexposure, the lesions were examined by microradiography and polarizing microscopy. Mineralization of the periphery of the initial lesion was increased before these treatments. At this peripheral zone, a relatively well-mineralized lamination occurred. The development of laminations at the periphery of the initial lesions seems to be related to noncontinuous remineralization.

ISSN:0008-6568    

DOI:10.1159/000260918

出版商:S. Karger AG    

年代:1986

数据来源: Karger

摘要:

Acid-softened bovine enamel slabs were mounted in acrylic mandibular removable appliances and worn by 8 male subjects. Control slabs were worn for 4 days without exposure to topical fluoride agents. The test slabs were brushed 4 times a day for 3 days with a 0.24% NaF dentifrice or rinsed 4 times a day for 3 days with a 0.02% APF mouthrinse and worn a 4th day without exposure to the fluoride agent. Microhardness values for both groups of test slabs were significantly higher than controls following intraoral exposure and after in vitro exposure to acid. The uptake of fluoride by both mouthrinse- and dentifrice-treated slabs was significantly higher than the controls.

ISSN:0008-6568    

DOI:10.1159/000260919

出版商:S. Karger AG    

年代:1986

数据来源: Karger

摘要:

A number of solutions used for topical application and mouth rinsing were analyzed and calcium fluoride formation on human enamel at 20 °C determined. In most solutions free fluoride and hydrogen fluoride were the main ion species, whereas stannous hydroxide and stannous fluoride ion pairs were the dominating components of stannous fluoride solutions. The calcium fluoride formation on enamel was assessed by chemical analysis. It was found that an increase in fluoride activity and a decrease in pH increased the calcium fluoride formation to almost the same extent

ISSN:0008-6568    

DOI:10.1159/000260920

出版商:S. Karger AG    

年代:1986

数据来源: Karger

ISSN:0008-6568    

DOI:10.1159/000260921

出版商:S. Karger AG    

年代:1986

数据来源: Karger

ISSN:0008-6568    

DOI:10.1159/000260922

出版商:S. Karger AG    

年代:1986

数据来源: Karger