The acidurance of glycolysis by intact cells of Streptococcus mutans GS-5, Streptococcus salivarius ATCC 25925, and Streptococcus sanguis NCTC 10904 was found to be highly dependent on membrane functions affected by gramicidin, which increases the proton permeability of cell membranes. Plots of % glucose utilized during two hours against suspension pH values for cells suspended in 100 mM phosphate buffer plus 1 mM MgCl2 plus 13.9 mM glucose indicated, for 50% glucose utilization, pH values of 5.0 for S. mutans, 5.7 for S. salivarius, and 6.2 for S. sanguis. Gramicidin treatment shifted these values to 6.0, 6.3, and 6.9, respectively. Growth of S. mutans and S. salivarius in complex media proved to be more acid-sensitive than was glycolysis, and in batch cultures, there was a well-defined, post-growth phase of glycolysis. Minimum pH values for growth and for glycolysis in medium with excess glucose were approximately 4.8 and 4.4, respectively, for S. mutans, and 4.9 and 4.3 for S. salivarius. S. sanguis was less aciduric and showed little differential acid sensitivity, with minimum pH values of about 5.2 for both growth and glycolysis. Fluoride acted to eliminate the differences in acidurance of growth and glycolysis for S. mutans or S. salivarius and to render both processes more acid-sensitive. Thus, glycolysis was more fluoride-sensitive than was growth. Growth was found to be acid-limited in media with initial glucose levels greater than 0.2, 0.3, and 0.5% (weight/volume) for S. sanguis, S. mutans, and S. salivarius, respectively, and to be glucose-limited at lower levels.(ABSTRACT TRUNCATED AT 250 WORDS)
The current study is among the first to report on the ability of annual measurements of SMS to identify long-term caries risk in both the primary and the mixed dentitions. Despite limitations in predicting caries risk using microbiological methods, this longitudinal study supports the overall benefits of this type of testing.
Numerous studies have reported a correlation between mutants streptococci levels and dental caries. The aim of this study was to assess the relationship between salivary mutans streptococci levels and caries in preschool children of low socioeconomic status. A total of 462 Head Start children, mean age 3.8 yr (range 2.0-5.3 yr), were examined by the modified method of Radike. Saliva samples from 458 of these children were collected with tongue blades and impressed onto mutants streptococci selective agar. Children's mutants streptococci levels were categorized as low (0 CFU), moderate (1-50 CFU) or high (> 50 CFU), and the mean dmfs was 0.40, 1.92 and 4.88, respectively. All study groups (Black, Hispanic and White) had infection rates of approximately 83%; however, 39.1% of Black children had high mutans streptococci levels compared with 28.4% of White children. Pit/fissure caries was the most prevalent disease type in children with moderate or high mutants streptococci levels, although White children in the high group had significantly less of this pattern than Blacks and Hispanics. Sensitivity, specificity, and positive and negative predictive values for the high mutants streptococci group were 91.3%, 57.5%, 69.3% and 86.3%. Results from this study indicate that differences between Black, Hispanic and White preschool children may influence caries activity within populations that have similar mutants streptococci infection levels and socioeconomic backgrounds.
The aim of this study was to assess the relationship between salivary mutans streptococcus (SMS) levels and the prevalence and incidence of dental caries in 148 children (mean baseline age 3.8 years) of low socioeconomic status. Caries data (dmfs) and semiquantitative SMS counts were obtained at baseline and annually for 2 years. The children were classified during each of the 3 years as low (0 colony-forming units; CFU), moderate (1–50 CFU), or high ( > 50 CFU) caries risk based on total SMS counts. The results indicated that the prevalence of dental caries increased with SMS levels at baseline and generally in both assessment years. At baseline the mean dmfs of the children classified as low, moderate, or high caries risk was 0.15,1.44, and 3.36, respectively, while the mean dmfs of the same children at year 2 was 1.18, 3.10, and 7.87, respectively. The mean dmfs of the high-caries-risk group increased by 79% between baseline and year 1 and by 30%between year 1 and year 2. At year 2,50% of the children in the low- and 47% in the moderate-caries-risk groups were caries free as compared with 11% in the high-caries-risk group. Thirty-three percent of the children examined remained in the same caries risk category from baseline to year 2; the incidence (▵dmfs) of dental caries in those children designated as low, moderate, and high caries risk during this period was 1.44, 3.36, and 10.07, respectively. The results indicate that there is an association between SMS levels and prevalence and incidence of dental caries in the primary teeth of these children and suggest that SMS levels may be useful in predicting the caries risk in the deciduous dentition of some populations.
Silver cations generated by passing low intensity direct current through pure silver electrodes were found to be sufficiently antibacterial to cause sterilization of samples of infected dentin. The optimal procedure involved a 5 microA current applied for 20 minutes with the anode then left in contact with the sample. Minimal inhibitory concentrations of electrically generated silver ions for representative oral bacteria were essentially equal to those for silver ions added as nitrate or fluoride salts, and medium constituents, including sodium thioglycolate, antagonized antibacterial action. A major advantage to the use of the electrode method is that it allows for continuous, focal application of antibacterial silver cations.
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