摘要:

The diffusion of fluoride ions from various concentrations of sodium fluoride solution into the dentine of decoronated human canine teeth, prepared as for reception of overdentures, was studied in vitro. The decoronated preparations were immersed for 7 days in 2.0, 1.5, 1.0, 0.5 and 0.05% solutions of neutral-pH sodium fluoride and then fluoride penetration into the prepared transverse face of the dentine was assessed by electron microprobe. Only with high concentrations of fluoride (2.0%) was there significant penetration. In peritubular dentine, fluoride penetration could be measured to a depth of 400 μm, but in intertubular dentine penetration did not take place beyond 100 μm. These findings call into question the efficacy of patient-administered caries prophylaxis with low-concentration fluoride treatments in overdenture case

ISSN:0008-6568    

DOI:10.1159/000261287

出版商:S. Karger AG    

年代:1990

数据来源: Karger

摘要:

The effects of low concentrations (1.0 mmol/l of selenite and seleno-dl-cystine were tested alone, or in combination with NaF, on growth, glycolysis, and survival of Streptococcus mutans GS-5. In batch culture, both selenium-containing compounds (1.0 mmol/l) inhibited the growth rate and final cell yield by 92% or greater; glycolysis, however, was not affected. The observed bactericidal action of selenite at 0.1 mmol/l was pH-dependent. Fluoride reduced the killing effect of SeO3 in the culture medium and in a lactate-acetate buffer system at pH 6.5, 5.0 and 4.0. These data indicate that selenium-containing compounds exert an antibacterial action on cells of S. mutans in a manner which leaves glycolysis unaffected.

ISSN:0008-6568    

DOI:10.1159/000261288

出版商:S. Karger AG    

年代:1990

数据来源: Karger

摘要:

An epidemiologic investigation to reliably identify caries-susceptible subjects by microbiological and chemical assessment of plaque and saliva is currently in progress. As part of that study, the numerical relationships of mutans streptococci, lactobacilli and total viable microflora in plaque and saliva among 12- to 15-year-old children in a fluoridated community were determined. Paraffin-stimulated whole saliva and pooled dental plaque were collected. Each sample was suspended in reduced transport fluid, chilled on ice, and assayed. The bivariate normal distribution was found to be a suitable model for the distribution of the pairs [numbers of bacteria in plaque (log10), numbers of bacteria in saliva (log10)]. Statistically significant positive correlations were found between numbers of mutans streptococci in plaque and saliva, and between lactobacilli in plaque and saliva.

ISSN:0008-6568    

DOI:10.1159/000261289

出版商:S. Karger AG    

年代:1990

数据来源: Karger

摘要:

The microfloras of fissure plaque samples removed from a total of 23 seriously mentally retarded adults, resident in two institutions, were examined and compared with the fissure microfloras found in 17 control subjects who were employees in both institutions. The samples were collected from both an intact fissure and a fissure with brown-stained defective enamel surface of the premolars of the lower jaw. Mutans streptococci, selected with MSB medium, were recovered from only one of the defective fissures of 13 patients who became retarded younger than 2 years of age, whereas 14 defective fissures of 17 controls harbored mutans streptococci. Four of 8 patients who became retarded older than 3 years of age harbored mutans streptococci. Lactobacilli were infrequently recovered from both patients and controls. The results are discussed in terms of the microbiological aspect of caries development in adults who became mentally retarded when young.

ISSN:0008-6568    

DOI:10.1159/000261290

出版商:S. Karger AG    

年代:1990

数据来源: Karger

摘要:

Occlusal caries depth was assessed in 47 extracted premolars and permanent molars by 4 observers on a rank scale by eye inspection, by film radiographs, and by 2 of the observers also by digitized radiographs after filtering and contrast enhancement of the image. Quantitative estimates of caries depth were obtained from the digitized radiographs. Accuracy of scorings was determined with the histologic section as validating criterion. Occlusal caries was present in a spectrum from incipient fissure decalcification to large cavity formation. Clinical as well as radiographic scorings most frequently under-estimated lesion depth. Accuracy of radiographic assessments increased substantially by digital processing of the radiographic image. Quantitative measures of caries depth on digitized radiographs were strongly correlated to the histologic measures (r = 0.91). Interobserver agreement was fair to moderate according to kappa coefficients for the clinical and the radiographic scorings. The agreement was highest for the scorings of the digitally enhanced images. The study suggests that digital processing of radiographic images constitutes a diagnostic aid that may give a more accurate estimate of occlusal caries depth.

ISSN:0008-6568    

DOI:10.1159/000261291

出版商:S. Karger AG    

年代:1990

数据来源: Karger

ISSN:0008-6568    

DOI:10.1159/000261292

出版商:S. Karger AG    

年代:1990

数据来源: Karger

摘要:

Fluoride-resistant strains of mutans streptococci have been found to be less cariogenic than their parent strains in the rat model system. Therefore, it is important to determine whether the use of fluorides in vivo will increase the fluoride resistance of mutans streptococci and thereby possibly decrease their cariogenic potential. We studied (1) the fluoride resistance of Streptococcus mutans C180-2 in rat dental plaque exposed to various fluoride treatments (experiment 1), (2) the cariogenic potential of the exposed plaque after transmission to other animals (experiment 2), and (3) whether the fluoride treatments favoured the establishment of in vitro induced fluoride-resistant S. mutans in competition with a fluoride-sensitive strain in rat dental plaque (experiment 3). In all experiments, specific pathogen-free Osborne-Mendel rats were used, and all animals received diet SSP 20/5, containing 20% (w/w) sucrose and 5% (w/w) glucose, and tap water ad libitum. In experiment 1, the rats were inoculated with S. mutans C180-2. For an experimental period of 44 days, the rats either received no F treatment or received NaF mixed in the diet and drinking water (20 or 60 ppm F) or were brushed 6 days per week with an aqueous NaF solution containing either 0.1% (w/v) or 1% (w/v) F, respectively. Bacteriological analyses at the end of the experiment revealed that none of the fluoride treatments had caused a detectable increase in the inherent fluoride resistance of S. mutans C180-2. In experiment 2, the rats were inoculated with pooled plaque samples collected from animals of the control group, the group that received 60 ppm F, or the group treated with 1% F in experiment 1, respectively. After an experimental period of 35 days, no significant differences were observed in amount or severity of fissure caries in the mandibular molars of animals inoculated with one of the pooled plaque samples or with the original S. mutans C180–2. In experiment 3, rats were inoculated with a mixture of equal numbers of colony-forming units of a fluoride-sensitive (C180-2SR) and a fluoride-resistant (C180-2FR) S. mutans strain and subjected to one of the F treatments described in experiment 1. The results showed that the fluoride-resistant strain had not emerged in rat dental plaque by day 14 after inoculation, irrespective of the F treatments. The fluoride-resistant strain did establish when inoculated separately. The results of the studies described here indicate that growth adaptation to fluoride resistance by S. mutans is not likely to occur in vivo, that fluoride does not induce a prolonged reduction in the cariogenicity of dental plaque, and that fluoride resistance impairs establishment of S. mutans when competing with fluoride-sensitive strain

ISSN:0008-6568    

DOI:10.1159/000261293

出版商:S. Karger AG    

年代:1990

数据来源: Karger

摘要:

As part of a major study to identify cariogenic elements of foods, the cariogenic potential of 22 foods relative to sucrose (confectioners’ sugar) was determined over six intubation rat caries experiments. Cariogenic potential indices were calculated for each food from sulcal and buccal-lingual caries based on both number and severity. Those foods with the lowest cariogenic potential indices were peanuts, gelatin dessert, corn chips, yoghurt, and bologna; with the highest cariogenic potential indices were sucrose, granola cereal, french fries, bananas, cupcakes, and raisins. There was no simple relationship between food sucrose content and caries. Enhanced cariogenic potential was associated with foods containing approximately 1% or more hydrolyzable starch in combination with sucrose or other sugar

ISSN:0008-6568    

DOI:10.1159/000261294

出版商:S. Karger AG    

年代:1990

数据来源: Karger

ISSN:0008-6568    

DOI:10.1159/000261295

出版商:S. Karger AG    

年代:1990

数据来源: Karger

摘要:

The amount of dentifrice used and ingested on three occasions by a group of 48 children aged between 3 and 5 years was measured. The purpose of the present study was to investigate the variability in the amount of dentifrice used and ingested. The quantity of toothpaste ingested was derived from the differences between the amounts used and rejected. On average, the difference in the amount used between any two brushings was less than 0.250 g for 66% of the subjects, and the difference in the amount ingested was less than 0.100 g for 69% of the children. There were no statistically significant differences in the quantities used and ingested between the three brushings.

ISSN:0008-6568    

DOI:10.1159/000261296

出版商:S. Karger AG    

年代:1990

数据来源: Karger