摘要:

Extracellular polysaccharides (EPS) synthesized by Streptococcus mutans in vitro and insoluble in the culture supernatant are shown to be mixtures of water-insoluble and water-soluble EPS. After dissolving in potassium hydroxide and subsequent neutralization only part of the EPS precipitates (insoluble fraction). Another part can be isolated from the neutralized solution by the addition of ethanol (soluble fraction). Some samples show remarkable amounts of carbohydrate material, soluble even in 70% ethanol or material which can pass dialysis membranes. The insoluble fraction shows a higher share of α-(l→3)-linkages and is less susceptible to dextranase than the soluble fraction. It is suggested that the soluble fraction might be surrounded by insoluble polysaccharide or might be linked to cell-associated glucosyl-transferase, thus becoming part of an insoluble complex. Insoluble EPS synthesized by isolated glucosyltransferase of 5. mutans showed no fractionation after alkaline treatme

ISSN:0008-6568    

DOI:10.1159/000260375

出版商:S. Karger AG    

年代:1979

数据来源: Karger

摘要:

Following infection by equivalent numbers of Streptococcus mutans serotypes a–e, gnotobiotic rats were monitored to determine which serotypes became implanted and their relative proportions when the animals were fed diets which contained glucose, sucrose or starch as the sole carbohydrate. S. mutans organisms were observed to colonize all sites sampled; the serotype prevalence differing considerably as the experiments progressed and according to the carbohydrate ingested by the animals. Serotype b organisms (rat strain FA-1) predominated in specimens from all sites. Serotype d organisms (strain 6715), frequently employed in caries studies involving the use of sucrose diets, required sucrose to colonize and remain on teeth in the gnotobiotic animals studied. Furthermore, colonization of the animals by S. mutans was observed to stimulate detectable levels of 7-S antibody to S. mutans in seru

ISSN:0008-6568    

DOI:10.1159/000260376

出版商:S. Karger AG    

年代:1979

数据来源: Karger

摘要:

Midmorning urine samples were collected from 623 first- and second-grade children in four elementary schools. The mean for water F content in the residential area from which the population was drawn was 0.024 ppm (55 samples). The mean urine F concentration for all subjects was 0.42 ppm (SD = 0.22). There were no significant differences in urine F levels as a factor of sex or age. Children living in the area for no more than 1 year excreted significantly higher levels of F in the urine than did the longer-resident youngsters. This is attributed to their probable exposure to higher F levels in drinking water prior to moving into this low-F area. The urine F mean was 17.5 times that of the drinking water F. Urine F measurements, therefore, cannot be taken as indicative of F content of drinking water when the concentration in water is very low.

ISSN:0008-6568    

DOI:10.1159/000260377

出版商:S. Karger AG    

年代:1979

数据来源: Karger

摘要:

Two versions of the kappa statistic, which corrects the observed proportion of agreement for the proportion of agreement to be expected by chance alone, are presented for measuring intra- and inter-examiner reliability on categorical scales. They are applied to data collected during three separate training and standardization sessions for a caries field trial. The data are also analyzed with respect to the caries reversal phenomenon.

ISSN:0008-6568    

DOI:10.1159/000260378

出版商:S. Karger AG    

年代:1979

数据来源: Karger

摘要:

Saline, Triton X-100 and acid-soluble inorganic phosphate were quantitatively assayed from freeze-dried dentine of sound and carious human teeth. The phosphate levels were measured from 5.0-mg (dry weight) samples of drilled dentine powder taken from 3 to 6 areas of a single tooth (93 teeth were used). The highest concentrations of total phosphate were in the peripulpal area of the crown. Root dentine contained less total phosphate than did crown dentine. The amount of total phosphate increased significantly with the age of the teeth. A decrease of 30–60% was observed when the dentine became carious. Hard dentine in the vicinity of the caries lesion (sclerotic, pigmented dentine) indicated about the same phosphate content as the dentine of corresponding areas of intact teeth. The mean NaCl-soluble fraction of the hard dentine was relatively constant. The values in crown odontoblastic dentine, however, revealed significant changes as a function of carious attack. The NaCl-soluble phosphate of soft caries dentine was somewhat higher than that of hard dentine. The possible role of NaCl-soluble phosphate ions in the regulation of phosphatase activity in the dentine is discusse

ISSN:0008-6568    

DOI:10.1159/000260379

出版商:S. Karger AG    

年代:1979

数据来源: Karger

摘要:

A double-blind clinical study extending over 3 years is reported. Two examiners independently examined 944 subjects to evaluate the efficacy of a calcium carbonate-based sodium monofluorophosphate dentifrice and a similar sodium monofluorophosphate dentifrice but with calcium glycerophosphate as an additive. Subjects brushed only at home withouth supervision. Subjects in booth treatment groups showed a statistically significant lower caries incidence than subjects in the control group. Both independent examiners detected a consistent, though statistically non-significant, trend towards lower caries increments in the group using the dentifrice containing both sodium monofluorophosphate and calcium glycerophosphate. Evaluation of caries incidence according to oral hygiene demonstrated statistically significant greater treatment effect and lower caries incidence with better oral hygiene. Although the examiners had not been calibrated, close agreement between their independent findings is shown.

ISSN:0008-6568    

DOI:10.1159/000260380

出版商:S. Karger AG    

年代:1979

数据来源: Karger

摘要:

The present study was undertaken to investigate the mineral uptake in fluorosed enamel in vitro. Bucco-lingual sections of severely fluorotic teeth were exposed to a mineralizing calcium phosphate solution supersaturated with respect to hydroxyapatite and under-saturated with respect to other calcium phosphates in order to favour apatite formation. The solution was renewed once a week, and concurrently the sections were washed in a hypochlorite solution for 30 sec or 5 min to prevent bacterial growth. The experiments were continued for 14 weeks at a temperature of 23 °C. The results of the experiments were evaluated chemically by changes in the liquid phase, and histologically by qualitative and quantitative imbibition studies in polarized light. A limited mineral uptake was demonstrated both chemically and histologically. By prolonging the hypochlorite treatment from 30 sec to 5 min an increase in mineral uptake was recorded

ISSN:0008-6568    

DOI:10.1159/000260381

出版商:S. Karger AG    

年代:1979

数据来源: Karger

ISSN:0008-6568    

DOI:10.1159/000260382

出版商:S. Karger AG    

年代:1979

数据来源: Karger

ISSN:0008-6568    

DOI:10.1159/000260383

出版商:S. Karger AG    

年代:1979

数据来源: Karger