摘要:

A comparison was made between the demineralization of enamel and dentine with and without abraded surfaces. This was done in a pH-cycling experiment for different demineralization/remineralization ratios – in the range from 1:1 to 1:4 – and for different fluoride additions (up to 2 ppm) in solution. A new automatic pH-cycling system, in which the de- and remineralization solutions have a constant composition during the de- and remineralization cycles, was used to create mineral loss in human dentine and enamel. Changes in mineral content were monitored by means of longitudinal microradiography. A linear correlation was found between the amount of mineral lost and the total demineralization time for both dentine and enamel. The demineralization rates were comparable for abraded enamel and dentine and for polished enamel and dentine, and this rate was roughly doubled by the removal of the outer surface for both tissues. This showed that the presence of the outer surface is equally important to dentine and enamel. Under the pH-cycling conditions used, a logarithmic relation was found between the addition of fluoride and the decrease in demineralization for both enamel and dentine. The inhibitory effect of fluoride on demineralization was most pronounced on abraded enamel, followed by pumice-polished enamel, abraded dentine and pumice-polished dentine. About 2 ppm fluoride was needed under the conditions used to stop enamel demineralization completely; in the case of dentine, however, this amount of added fluoride did not inhibit demineralizat

ISSN:0008-6568    

DOI:10.1159/000261385

出版商:S. Karger AG    

年代:1991

数据来源: Karger

摘要:

The aim of the present paper was to study the relation between the development of enamel erosion and caries lesion. Intact teeth were exposed to a gently agitated 50 mM acetate buffer, with or without fluoride for various periods of time. Further, intact teeth were exposed to an agitated 0.2 M HCl solution. It was found that irrespective of experimental conditions the aqueous phase was initially unsaturated with respect to both hydroxyapatite and fluorapatite during which period fluorhydroxyapatite was dissolved. Histological examination showed that the dissolving apatite originated from the enamel surface and the resulting lesion exhibited the signs of a dental erosion. The depth of the erosive lesion was found to be a direct function of the amount of mineral dissolved before the aqueous phase became saturated with respect to fluorapatite. The calcium, phosphate and fluoride dissolved made the aqueous phase first saturated and later supersaturated with respect to fluorapatite and a reuptake of fluoride in the enamel began, now under development of a caries-like lesion with preservation of the surface layer over a subsurface demineralizing zone. The demineralization depended on the volume of the aqueous phase. In conclusion, in a closed system with a limited amount of unsaturated solution a double lesion, an erosion over a caries lesion, will develop according to the changing saturation with respect to fluorapatite.

ISSN:0008-6568    

DOI:10.1159/000261386

出版商:S. Karger AG    

年代:1991

数据来源: Karger

摘要:

A within-subject double-blind cross-over study was carried out to examine whether the chemical composition of approximal plaque was altered 1 and 24 h after brushing with fluoride toothpaste. Three fluoride toothpastes were tested, containing either sodium monofluorophosphate with calcium glycerophosphate supplement and calcium carbonate abrasive, a combination of sodium monofluorophosphate and sodium fluoride with the same supplement and abrasive or sodium fluoride with a silica abrasive. A fluoride-free toothpaste with a silica abrasive acted as the control. 19 subjects used the toothpastes separately in randomised order for 1 week each prior to collection of plaque. Contralateral half-mouth approximal plaque samples were collected 1 and 24 h after the last use of each toothpaste. Fluoride, calcium and inorganic phosphorus concentrations of plaque were estimated. The results indicated that brushing with toothpastes containing fluoride and/or calcium supplements resulted in increased concentrations of these constituents in approximal plaque 1 h after brushing. These elevated levels of inorganic ions were not observed in the samples collected 24 h after brushing. It was concluded that the potentially beneficial effect of a raised concentration of fluoride and calcium in approximal plaque observed soon after brushing is lost during the following 24 h.

ISSN:0008-6568    

DOI:10.1159/000261387

出版商:S. Karger AG    

年代:1991

数据来源: Karger

摘要:

A fluorescent dye was applied to extracted premolars with either early artificial lesions or natural white-spot lesions. The teeth were placed in an approximal geometry, and with a specially designed fibre-optic probe the fluorescence of the dye was measured in the lesions. The same fibre-optic probe was used to measure the transmission of light at a wavelength where the dye does not absorb. This transmission of light was used to correct the fluorescence for attenuation by the intermediate layer of sound enamel situated between the probe and the lesion. Both signals varied with time because of the necessary addition of ethanol during the measurement. The mineral loss from the lesions was measured with wavelength independent microradiography (WIM) for the artificial lesions, and the optical caries monitor (OCM) for the natural white-spot lesions. The correlation coefficient betweeen corrected fluorescence and mineral loss was r = 0.86. The results indicate that measurement of dye uptake may be a very sensitive method to diagnose early approximal caries lesions and may enable quantification of these lesions.

ISSN:0008-6568    

DOI:10.1159/000261388

出版商:S. Karger AG    

年代:1991

数据来源: Karger

摘要:

We studied dental caries susceptibility in various inbred mice strains infected with Streptococcus mutans and the inheritance pattern in the F1 and the N2 backcross animals. A high caries score was observed in four laboratory strains, BALB/cAJcl, C57BL/6NJcl, C57BL/10Slc and DBA/2NJcl. Three strains, C3H/HeNJcl, AKR/JSlc and CBA/JNCrj, showed less caries. Males of strain C57BL/10Slc (mean caries score = 112.2) and females of strain C3H/HeNJcl (mean caries score = 24.0) were chosen for examinations of the inheritance of the caries susceptibility. The mean caries score in (C57BL/10Slc×C3H/HeNJcl) F1 hybrids was 98.4, demonstrating that F1 progenies were susceptible. A number of N2 mice were obtained by mating the F1 male and the C3H/HeNJcl female. The caries scores of these N2 male mice had an extensive range, from 14 to 194. Assuming that a caries score over 74 (median of the scores between C57BL/10Slc and C3H/HeNJcl) belonged to the highly caries-susceptible group, N2 mice could be divided into groups with low or high caries susceptibility. Furthermore, the effect of nu/nu mutation on caries susceptibility in mice was also examined

ISSN:0008-6568    

DOI:10.1159/000261389

出版商:S. Karger AG    

年代:1991

数据来源: Karger

摘要:

Propolis, the resinous hive product collected by bees, is important in the defense of the hive. The effects of propolis on growth and glucosyltransferase activity of Streptococcus sobrinus 6715, Streptococcus mutans PS14 and Streptococcus cricetus OMZ61 in vitro, and on dental caries in rats infected with S. sobrinus 6715 were investigated. Propolis had antimicrobial activity against S. sobrinus, S. mutans and S. cricetus, and inhibited both water-insoluble glucan synthesis and glucosyltransferase activity. In rats inoculated with S. sobrinus, about half of their fissures were carious, while dental caries was significantly less (p = 0.01) in rats given propolis. Dental caries was markedly decreased by the multiple actions of propolis which had antimicrobial activity, inhibited water-insoluble glucan synthesis, and inhibited glucosyltransferase activity. No toxic effects of propolis on the growth of rats were observed under experimental conditions in this study. These results suggest that propolis can control dental caries in the rat model system.

ISSN:0008-6568    

DOI:10.1159/000261390

出版商:S. Karger AG    

年代:1991

数据来源: Karger

摘要:

The cariogenicity of Ferrero Milchschnitte® and apple was tested in rats using a frequency-controlled feeding machine. Twelve litters of Osborne-Mendel rats orally infected with Streptococcus sobrinus OMZ-176 and Atinomyces viscosus Ny-1 were used. Four treatment groups were tested: (1) cooked starch/sucrose 1:1 as positive control; (2) Ferrero Milchschnitte; (3) apple; (4) gastric intubation only as negative control. Groups 1–3 were additionally fed by gastric intubation with essential nutrients. Rats on Milchschnitte and apple had less fissure and smooth-surface caries than rats on a starch/sucrose diet, but significantly more than the negative controls. The Milchschnitte group exhibited less plaque extent than the positive and the negative control. The apple group showed a higher plaque extent and massively extended erosions on molar surfaces. The CFU means of S. sobrinus were decreasing from treatment 1–4. Although differences between treatments were not significant, they were associated by concomitantly decreasing caries incidence. The test foods were also assessed using intraoral plaque-pH telemetry in 6 human volunteers. Both Milchschnitte and apple were acidogenic in human telemetry. They can therefore not be regarded as safe for t

ISSN:0008-6568    

DOI:10.1159/000261391

出版商:S. Karger AG    

年代:1991

数据来源: Karger

摘要:

The objectives of this study were to test the applicability of photocell measurements in approximal caries diagnosis and to evaluate the use of radiographs as validating criterion. Forty extracted premolars were selected, and the progression of the approximal lesions was graded clinically and radiographically by three examiners. Each tooth was transilluminated from the occlusal surface, and the throughput of light at the approximal surface was measured by a photocell. Together with clinical examination, the results of microradiographic analysis served as validating criterion in this study. The results indicate that photocell measurements can be useful in the diagnosis of incipient approximal caries lesions. Radiographs have a restricted value as validating criterion in diagnostic studies pertaining to incipient caries.

ISSN:0008-6568    

DOI:10.1159/000261392

出版商:S. Karger AG    

年代:1991

数据来源: Karger

摘要:

The study compared visual inspection, conventional film radiographs, xeroradiographs, and digitized radiographs for the detection of caries in occlusal surfaces without cavitation. 166 extracted premolars and permanent molars without macroscopic cavitation were included. Eight observers assessed five grades of occlusal caries by visual inspection and by the three imaging techniques. Histologic sections (700–1,000 μm) served as validating criterion for the presence and depth of carious lesions, 82 teeth being found carious (27 with deep dentinal involvement) and 84 being scored as sound. Approximately 20% of the dentinal carious lesions were detected by visual inspection and 40% by conventional film radiography (both with a minimal number of false-positive observations). By xero- and digital radiography, an increasing number of false-positive scorings was seen. By digital radiography the true-positive detection rate was similarly increased to 60%. The predictive values of a positive test were, on average, 0.85 for visual inspection, 0.89 for film, 0.78 for xero-, and 0.82 for digital radiography and for a negative test 0.56, 0.61, 0.61, and 0.69, respectively. However, digital radiography was able to detect over 70% of deep dentinal lesions in contrast to 45% by the other two imaging methods, without an increase in false-positive diagnoses of truly caries free teeth, compared with the other techniqu

ISSN:0008-6568    

DOI:10.1159/000261393

出版商:S. Karger AG    

年代:1991

数据来源: Karger

摘要:

The purpose of the present work was the construction of statistical models which allow the prediction of future high caries increments on the basis of the state of primary teeth and first molars taking into account both precavity lesions and DF experience. A child was considered to be experiencing ‘high caries increment’ when it had at least four new lesions (new DFS) 4 years after the first examination. Two data sets of children aged 7–10 years were analysed: (1) 803 children examined in 1980 and in 1984. The proportion of children with ‘high caries increment’ was 25.0%. (2) 477 children examined in 1984 and in 1988. In this group, the proportion of children with high caries increment was 16.6%. In the first group with higher prevalence of caries, sensitivity and specificity were found to be on average at 70%. In the second group, sensitivity and specificity were 77% on average. This result shows that caries prediction may be at least as successful when a ‘refined’ set of clinical data is used instead of a less extensive set of caries data complemented by salivary buffering capacity and microbi

ISSN:0008-6568    

DOI:10.1159/000261394

出版商:S. Karger AG    

年代:1991

数据来源: Karger