摘要:

Changes in plaque pH (Stephan curves) after sugar mouth rinses, observed by the method of Frostell [1970], may be used to test the effect of factors possibly related to caries. Relationships observed between the Stephan curves and the salivary responses (pH and flow rate) suggest that the pH of saliva is a major factor controlling plaque pH. Modification of the Stephan curve may be more readily achieved by increasing the neutralising action of the saliva than by altering the acid-producing potential of the plaque.

ISSN:0008-6568    

DOI:10.1159/000260206

出版商:S. Karger AG    

年代:1976

数据来源: Karger

摘要:

Seven water-insoluble glucans were prepared enzymatically as described previously. In addition, glucan from Streptococcus mutans strain LM7 (serotype Lancefield Group E) was synthesized. Glucans were hydrolyzed with dextranase, mutanase and mutanase plus dextranase (1:1) until no further degradation occurred (100–150 h). Hydrolysis was measured by two methods: (1) as percent glucan solubilized based on total carbohydrate remaining in the supernatant after centrifugation, and (2) as percent reducing groups released. In all cases except glucan OMZ176, the percent carbohydrate solubilized by mutanase was greater than the percent reducing groups released. It is not necessary to hydrolyze completely a glucan in order to solubilize it. Comparison of solubilization by dextranase versus mutanase indicated that some glucans were solubilized more by dextranase, others by mutanase and some about the same. The combined hydrolytic action of the two enzymes was more effective and solubilization was more rapid than either enzyme acting separately. On some glucans their action was synergistic, the glucans were solubilized from 60 to 95%. Physical properties, such as specific rotation, intrinsic viscosity and infrared spectrum of the glucans was determined. A high specific rotation, low intrinsic viscosity and high ratio of free reducing end groups to total carbohydrate corresponded to a high degree of glucan branching. An absorption peak specific for α-1,3 linkage was found at 822 cm-1. Differences between glucans in susceptibility to hydrolysis, specific rotation, infrared spectra, intrinsic viscosity and reducing end groups reflect structural differences. These findings emphasize the heterogeneity of glucans that can be encountered in dental plaq

ISSN:0008-6568    

DOI:10.1159/000260207

出版商:S. Karger AG    

年代:1976

数据来源: Karger

摘要:

The in vitro attachment of Streptococcus mutans, strain KPSK 2, to hydroxyapatite under various conditions was studied in a sedimentation system. The effect of bacterial concentration, saliva concentration and amounts of apatite was investigated. The number of colony-forming units of bacteria per milligram of apatite decreased with increasing concentrations of saliva. Preincubation of saliva and bacteria prior to the addition of apatite constantly gave the lowest uptake of bacteria. When the saliva was treated with bacteria to remove the receptor-specific substances no effect of concentration of the supernatant on the bacterial uptake was found. A hypothesis for the mechanism of the action of specific salivary substances on bacterial uptake on to apatite is suggested.

ISSN:0008-6568    

DOI:10.1159/000260208

出版商:S. Karger AG    

年代:1976

数据来源: Karger

摘要:

Clinical studies have shown that fissure sealants are not retained by primary teeth as well as they are by permanent teeth, presumably due to the presence (of a surface layer of prismless enamel in primary teeth. In order to compare the enamel structure and main crystallite orientation on occlusal surfaces, sections from primary molars and permanent premolars were examined by polarized light microscopy. Crystallite orientation to the enamel surface was measured at various distances from the fissure entrance. It was found that the crystallites were arranged almost perpendicular to the enamel periphery whilst the prisms formed an acute angle with the periphery. Only on rare occasions was prismless surface enamel observed. It was concluded that main crystallite orientation and prism arrangement were alike in primary and permanent occlusal enamel, and that the poor retention of sealants on primary teeth cannot be explained by the presence of a prismless surface.

ISSN:0008-6568    

DOI:10.1159/000260209

出版商:S. Karger AG    

年代:1976

数据来源: Karger

摘要:

Acid-etched samples of surface, subsurface and inner lingual enamel and buccal whole enamel samples were analyzed for strontium and fluoride. The individuals’ caries prevalence was known. The teeth were obtained from life-long residents of specific towns in New England, the Central Atlantic and Southern Atlantic coastal and interior areas, all of whose water supplies were low in fluoride 7 DMFT) were compared to that from low caries individuals ( < 3 DMFT), at least twice as much strontium and fluoride were found in the surface and subsurface enamel of teeth from the low caries grou

ISSN:0008-6568    

DOI:10.1159/000260210

出版商:S. Karger AG    

年代:1976

数据来源: Karger

摘要:

The original sample consisted of 179 randomly chosen children aged 6 years and 1 month at the time of examination. Of these children, those 88 were selected who had been exposed, since the age of 4, to consistent oral hygiene measures and dietary habits. The investigation involved clinical registration of caries, including subsurface lesions, and restorations in buccal and lingual surfaces in primary molars and cuspids. The mesial surface of second molars, distal and mesial surfaces of first molars, and the distal surface of cuspids were recorded from X-ray pictures. 85 children were classified as follows, beletary habits: (1) > 6 or (2) 5–6 meals and snacks a day including at least one ‘unsuitable’ Dack with a high-sucrose component, or (3) < 6 consumptions with suitable snacks sntween meals. Oral hygiene habits: (1) an adult brushed the child’s teeth at least once a day or (2) the children did it at least once a day themselves. The statistical analysis of the results revealed a clear tendency that the effectiveness in prevention of buccal and lingual caries by practicing one of the two habits at the most favourable level was greatest when the other habit was most unfavourable. This was not true for proximal caries, but, at both oral hygiene levels, the number of carious surfaces decreased with more favourable dietary habits. The validity of the results is discussed with proper consideration of the differences between neighbouring combi

ISSN:0008-6568    

DOI:10.1159/000260211

出版商:S. Karger AG    

年代:1976

数据来源: Karger

ISSN:0008-6568    

DOI:10.1159/000260212

出版商:S. Karger AG    

年代:1976

数据来源: Karger