Effects of pyridoxine, phytate and invert sugar on plaque composition and caries activity in the monkey (Macaca fascicularis)

Role of dietary habits and diet in caries occurrence and severity among urban adolescent school children

To identify the role of dietary habits (type of diet, skipping meals, snacking in-between meals and frequency of visits to fast food restaurants) in caries occurrence and severity. To explore the correlation between frequency of intake of selected foods and dental caries. A cross-sectional study was carried out on adolescent children (n = 916) of age 13-19, following a two-stage random sampling technique. Data were collected using a pretested questionnaire. Questionnaire included demographic details, dietary habits of children and food frequency table that listed selected food items. The dependent variable-dental caries was measured using the decayed, missing, filled teeth (DMFT) index. The prevalence of dental caries in this study population was 36.7% (95% confidence interval: 33.58-39.82). The mean DMFT was 1.01 (±1.74). No statistically significant difference found between caries occurrence and type of diet (P = 0.07), skipping meals (P = 0.86), frequency of eating in fast food stalls (0.86) and snacking in between meals (0.08). Mean DMFT values were higher among nonvegetarians and among children who had the habit of snacking in between meals. Frequency of intake of selected food items showed that mean frequency intake of carbonated drinks and confectionery was higher among children who presented with caries when compared to caries-free children (P = 0.000). Significant correlation found between mean DMFT and mean frequency intake of carbonated drinks and confectionery. Odds ratios were calculated for the same for frequency ≥4 times/day for confectionery and ≥4/week for carbonated drinks and results discussed. Frequent intake of carbonated drinks and confectionery is harmful to oral health that eventually reflects on general health. Educating the adolescent children on healthy dietary habits should be put in the forefront.

Pyridine analogs inhibit the glucosyltransferase of Streptococcus mutans

Soluble glucan synthesis catalyzed by dextransucrase preparations from Streptococcus mutans 6715 were inhibited by pyridoxal-5-phosphate and several other pyridine analogs, including pyridoxine, pyridoxamine, pyridoxamine-5-phosphate, pyridoxal, and 4-pyridoxic acid. Pyridine and pyridine-4-carboxaldehyde were not effective inhibitors of the enzyme. Kinetic analyses suggested that pyridoxal-5-phosphate is a noncompetitive inhibitor of dextransucrase. The inactivation was dependent on time, pyridoxal-5-phosphate concentration, and hydrogen ion concentration. Apparent Ki values were 4.9 mM at pH 7.0 and 4.2 mM at pH 5.5. Dextransucrase activity could be restored by dialysis to remove the inhibitors. Maximum inhibition was observed after a 120-min incubation of the enzyme with pyridoxal-5-phosphate. The pH optima for inhibition by pyridoxal-5-phosphate were 4 and 7. The sucrose-dependent adherence of S. mutans cells to saliva-coated hydroxylapatite beads was also inhibited by pyridoxal-5-phosphate but only marginally by the other pyridine anatogs. In addition, pyridoxal-5-phosphate markedly reduced the rate of acid production by intact S. mutans cells from sucrose or glucose substrates. Another pyridoxal-5-phosphate analog, 2-methyl-5-hydroxypyridine, was also effective in preventing the production of acid by S. mutans from sucrose or glucose. When S. mutans cells were preincubated with pyridoxal-5-phosphate or pyridine analogs, significant reductions in the rate of D-glucose uptake were observed. It is suggested that the inhibition of dextransucrase occurs because of a change iun enzyme conformation which results from the binding of the pyridine derivatives. The results suggest that pyridoxal-5-phosphate or structural analogs may ultimately be useful in reducing the incidence of dental caries.

The streptococcal flora of the tongue of the monkey Macaca fascicularis

The major streptococcal biotypes in the 8 monkeys investigated resembled Streptococcus sanguis and Streptococcus mitior with Streptococcus salivarius forming only 5 to 6 per cent of the total colony count and being isolated from only 4 monkeys. The predominant tongue streptococci were not isolated from the dental plaque. Similarly, Streptococcus mutans, present in large numbers in the plaque of monkeys fed sucrose-rich diets, was isolated from the tongue of only 2 animals and formed only 2.4 per cent of the total colony count. Changing from a starch-based maintenance diet to sucrose-rich diets did not significantly alter the tongue flora except that the proportion of typical Strep. sanguis was significantly reduced. The oral streptococcal flora of monkeys is similar in distribution to that found in the human mouth.

Microbial analyses of dental plaque of monkeys (Macaca fascicularis) using fluorescent antibody techniques

Selected microbial components in supragingival dental plaque from recently captured monkeys were determined. Using specific fluorescent antibody (FA) conjugates S. sanguis was found to constitute an average of 11.8% of all cells. The populations of Actinomyces accounted for 20.7% (range 5-31) with A. viscosus and A. naeslundii as predominant species. Few lactobacilli were encountered. S. mutans was not detected in any specimens when examined by culture and FA.