摘要:

A novel lower removable acrylic appliance to investigate the pathogenesis of the incipient carious lesion in enamel is described. Pilot enamel demineralisation and remineralisation studies have been undertaken. Ground enamel sections were cut from undemineralised enamel or from teeth on which artificial lesions had been created. These were varnished and mounted on the base of experimental troughs in an appliance and subjected to the natural oral environment of a volunteer’s mouth. The individual’s diet was not altered but an F or non-F dentifrice was used as dictated by the experimental protocol. Microradiographs of the tooth sections were taken at baseline and at weekly intervals. In the demineralisation study, 3 sections out of 20 showed areas of demineralisation after only 2 weeks, whereas in the remineralisation study an increase in the mineral content of the surface zone was evident in 3 out of 4 sections after the same period, but in all sections after 5 we

ISSN:0008-6568    

DOI:10.1159/000260963

出版商:S. Karger AG    

年代:1986

数据来源: Karger

摘要:

The microbiological species and acid/anion profiles of the plaque-like material which accumulates on exposed surfaces of enamel sections mounted in the experimental troughs of the previously described in situ caries appliance were studied. Each experiment lasted 1 week and the volunteers’ diet and oral hygiene patterns were unaltered, except that interproximal plaque was allowed to accumulate in an interproximal space adjacent to one of the troughs. The appliance was removed once per day to facilitate cleansing of the lower lingual aspects of the natural dentition. The acid/anion profiles of the appliance samples were similar to plaque of equal maturity from the adjacent interproximal site. Qualitatively the microbiological species recovered from the natural and appliance plaque were similar and within the normal range for 7- to 9-day natural plaque. When the composition of appliance and natural plaque was compared some quantitative differences were found. Thus it would seem that the previously reported de- and remineralisation investigations using this appliance were carried out under the influence of an ecosystem similar to that of an adjacent interproximal site of the natural dentition. In addition, this appliance should provide a means for the study of the microbiology and biochemistry of early enamel carie

ISSN:0008-6568    

DOI:10.1159/000260964

出版商:S. Karger AG    

年代:1986

数据来源: Karger

摘要:

Extensive ‘white spot’ and ‘brown/white spot’ lesions with intact surfaces in 11 molars were investigated by microradiography and electron microprobe analysis for Fe, Ca, Na and Cl. At the surface of the brown spots some Fe was found. Within the lesions a preferential dissolution of Na and a slight enrichment of Cl was found. This suggests that Na and Cl are sited in different parts of the mineral and the Na-containing part appears to be more soluble. The Na and Cl contents of a lamination approach those of adjacent sound enamel. This indicates that laminations do not result from major reprecipitation of a less soluble calcium phosphate within the formed lesion, but that the mineral is protected from local dissolution early in the process. A possible mechanism is di

ISSN:0008-6568    

DOI:10.1159/000260965

出版商:S. Karger AG    

年代:1986

数据来源: Karger

摘要:

Saccharin inhibited the rate of growth, the amount of acid produced, and glucose utilization by Streptococcus mutans NCTC 10449. One possible mechanism by which saccharin mediates its negative effects upon glucose catabolism is by inhibiting lactate dehydrogenase, the enzyme which catalyzes the terminal, regulatory step in the Embden-Meyerhof-Parnas pathway. The inhibition of lactate dehydrogenase activity by saccharin is dependent upon the fact that it competitively inhibits the binding of its reduced coenzyme, NADH, to the enzyme. The Ki value for saccharin estimated from Dixon plot analysis is 6.2 mM and the inhibitor increased the Km value of NADH from 0.033 to 0.250 mM. In contrast, saccharin had no effect upon the interaction of either its allosteric effector, fructose-1,6-diphosphate, or its substrate pyruvate, with the enzyme. Lactate dehydrogenases assayed in cell-free extracts obtained from members of other S. mutans serotype groups and other oral streptococcal species were also inhibited by saccharin. Saccharin also served to inhibit NAD(H)- and NADP(H)-dependent oxidoreductases in addition to lactate dehydrogenase when assayed in cell-free extracts from S. mutans NCTC 10449 and Streptococcus faecalis. Thus, the saccharin-mediated inhibition of pyridine nucleotide-dependent oxidoreductases may be one manner by which it effects glucose metabolism by this organism.

ISSN:0008-6568    

DOI:10.1159/000260966

出版商:S. Karger AG    

年代:1986

数据来源: Karger

ISSN:0008-6568    

DOI:10.1159/000260967

出版商:S. Karger AG    

年代:1986

数据来源: Karger

ISSN:0008-6568    

DOI:10.1159/000260968

出版商:S. Karger AG    

年代:1986

数据来源: Karger

ISSN:0008-6568    

DOI:10.1159/000260969

出版商:S. Karger AG    

年代:1986

数据来源: Karger

ISSN:0008-6568    

DOI:10.1159/000260970

出版商:S. Karger AG    

年代:1986

数据来源: Karger

ISSN:0008-6568    

DOI:10.1159/000260971

出版商:S. Karger AG    

年代:1986

数据来源: Karger

ISSN:0008-6568    

DOI:10.1159/000260972

出版商:S. Karger AG    

年代:1986

数据来源: Karger