摘要:

The effects of Actinomyces viscosus on the establishment and symbiosis of Streptococcus mutans and Streptococcus sanguis and of the sucrose concentration of the diet in relation to caries in rats were investigated. SPF-Osborne Mendel rats were erythromycin-treated and inoculated with Strep. mutans OMZ176E and Strep. sanguis Ny101E. In a second experiment SPF rats were superinoculated with A. viscosus Ny1, Strep. mutans OMZ176E and Strep. sanguis Ny101E. During the experiments the microbial composition of the plaque was followed. The proportion of the inoculated strains in the cultivated plaque flora was relatively low, being 50% in the erythromycin-treated rats and 85% in the SPF rats. A resistance against colonization of Strep. mutans OMZ176E was found in the rats pre-inoculated with A. viscosus Ny1 and Strep. sanguis Ny101E. No effect of the sucrose concentration in the diet on the bacterial composition and on the amount of plaque was observed. No positive correlation was found between the amount of plaque and the incidence of caries lesions. A significant positive correlation between the sucrose content of the diet and the incidence of fissure and smooth surface lesions was found. A predominant demineralization of smooth surface and distal fissures was observed in the erythromycin-treated rats that were inoculated with Strep, mutans OMZ176E. The results suggest that the concentration of sucrose in the diet and the microbial composition, rather than the gross amount of plaque, are the important factors in the caries process in rats.

ISSN:0008-6568    

DOI:10.1159/000260138

出版商:S. Karger AG    

年代:1975

数据来源: Karger

摘要:

An investigation into occurrence of dextranase in human oral streptococci revealed that cell extracts of 8 out of 25 strains contained an enzyme, α-1,6-glucan glucohydrolase, that hydrolyzed the α-(1 → 6)-glucosidic linkages in dextran and isomaltose. Glucose was the only product of low molecular weight released by this enzyme. Six strains contained a different dextranase that released oligosaccharides of the isomaltose series from dextran. In the case of Streptococcus mutans IB16, it was established that the main oligosaccharide products were isomaltotetraose and isomaltopentaose. Cell-free filtrates from 14 of the 25 strains synthesized extracellular polysaccharides from sucrose, and eleven of the filtrates produced water-insoluble glucans. Dextranase occurred in five of the strains that synthesized glucan and in five strains that were unable to synthesize extracellular polysaccharides. All the insoluble glucans were partially hydrolyzed by a fungal α-(1 → 3)-glucanase. None of the cell-extracts or cell-free filtrates was able to hydrolyze α-1,3

ISSN:0008-6568    

DOI:10.1159/000260139

出版商:S. Karger AG    

年代:1975

数据来源: Karger

摘要:

Sound premolars were demineralized for 4, 6, 9, and 11 days in buffer solutions of either pH 4, 4.5, or 5. Lesions were examined by quantitative microradiography. The thickness of the surface layer, depth of the lesion and degree of demineralization were studied as a function of pH and demineralization time.

ISSN:0008-6568    

DOI:10.1159/000260140

出版商:S. Karger AG    

年代:1975

数据来源: Karger

摘要:

The solubility of powdered hydroxyapatite (HA) in acidic buffer solution (pH 4.65) was reduced by 71% by adding sufficient fluoride (F––; either by previously treating the HA with NaF solution or by introducing NaF at the start of the dissolution) to replace approximately 25% of all surface unit cell OH–– ions. The same amount of F–– was less effective if added as NaF after the start of the dissolution. Addition of CaF2 had no effect. The results indicate that the influence of F–– on HA solubility cannot be attributed to CaF2 (either as a layer or as discrete crystallites) or to a fluorapatite layer and suggest that the rate of HA dissolution is modified by a rapidly attained F–– equilibrium at the

ISSN:0008-6568    

DOI:10.1159/000260141

出版商:S. Karger AG    

年代:1975

数据来源: Karger

摘要:

A microsampling technique was used to measure enamel fluoride concentrations before, immediately after, 1 week after, and 3 months after an application of an APF or NH4F solution on the maxillary anterior teeth of 63 children. The fluoride treatments were preceded by a 1-min application of 0.05 m H3PO4. It was found that NH4F produced an initial enamel fluoride level much higher than that produced by APF. One week after treatment, the fluoride concentrations produced by NH4F were still higher than those obtained with APF. Three months after treatment there was no difference between the NH4F and APF groups. Both groups, however, were observed to have lower fluoride concentrations than before treatment.

ISSN:0008-6568    

DOI:10.1159/000260142

出版商:S. Karger AG    

年代:1975

数据来源: Karger

摘要:

A follow-up study of 66 children, examined for dental caries at the age of 3, was carried out when these children had reached the age of 6. Caries prevalence in the primary dentition at the final examination as well as caries incidence during the 3-year period was compared to the fluoride content of the enamel measured by an abrasive biopsy technique on the buccal surfaces of the upper primary cuspids. No statistically significant correlation between the two parameters could be established. It was noted that a combination of low fluoride level in the enamel and high prevalence or incidence of dental caries was observed in only very few individuals.

ISSN:0008-6568    

DOI:10.1159/000260143

出版商:S. Karger AG    

年代:1975

数据来源: Karger

摘要:

The present experiments showed that fluoride and monofluorophosphate in low concentrations could desorb albumin and salivary glycoprotein adsorbed to hydroxyapatite in vitro. It is suggested that the principle involved is competitive inhibition, the fluoride and monofluorophosphate ions replacing acidic protein groups adsorbed to calcium ‘sites’ on the mineral surface. Bacteria adsorbed to hydroxyapatite could be desorbed in the same way indicating a similar mechanism. The adsorption of biological material to teeth seems to be strongly dependent on the surface chemistry of the teeth. Desorption of pellicle protein and bacteria may be one of the mechanisms by which fluoride and monofluorophosphate exert their cariostatic effect in vivo<

ISSN:0008-6568    

DOI:10.1159/000260144

出版商:S. Karger AG    

年代:1975

数据来源: Karger

摘要:

Two clinical trials have been performed. In the first series the oral retention of chlorhexidine after mouth rinses of various pH values was determined, employing 14C-ring-labelled chlorhexidine for quantitation. The amount of chlorhexidine retained in the mouth was found to be considerably less when the mouth rinses were adjusted to low pH values (1.5 and 3.0) than when the pH was neutral or alkaline (6.4 and 9.0). In another series the plaque formation during a 3-day period without oral hygiene was estimated, employing chlorhexidine mouth rinses of various pH values. The plaque-inhibiting capacity of chlorhexidine was almost eliminated by lowering the pH of the mouth rinses to 1.5 or 3.0. Bacteriologic in vitro tests, employing a cariogenic streptococcus as the target bacteria, failed to demonstrate differences between the bactericidal effect of the drug at low and high pH. The findings that both the plaque-inhibiting property of chlorhexidine and the retention of the drug in the oral cavity were pH-dependent support the hypothesis that the drug’s clinical effect is related to its retention in the mout

ISSN:0008-6568    

DOI:10.1159/000260145

出版商:S. Karger AG    

年代:1975

数据来源: Karger

摘要:

Isoproterenol has been reported to alter salivary gland development in the rat. Because salivary glands and the in rats saliva they produce play an important role in the etiology of dental caries, the effect of this pharmacologic agent on the caries process was investigated. Rat pups born to and suckled by dams fed isocaloric 8 or 25% protein diets were injected intraperitoneally with either 16 mg/kg isoproterenol or isotonic saline from day 6 to 16. From weaning on, all pups were fed a caries-promoting diet. Caries scores for molars from rats treated with isoproterenol were higher than those of control rats. It is concluded that isoproterenol administration to suckling rats during development of salivary glands induced changes which resulted in an increased dental caries susceptibility regardless of nutritional status.

ISSN:0008-6568    

DOI:10.1159/000260146

出版商:S. Karger AG    

年代:1975

数据来源: Karger

ISSN:0008-6568    

DOI:10.1159/000260147

出版商:S. Karger AG    

年代:1975

数据来源: Karger