Cariogenic microorganisms, saliva flow and dietary fibre predicts caries activity

The prediction of long term caries development is still unreliable. Objectives: This study used conventional caries activity tests and the growth of mutans streptococci and Lactobacilli on impressions of teeth to identify caries prone subjects. Methods: Twenty-seven dental students were examined for an increase in caries over 4 years. A plaque index, saliva flow, buffering capacity and lysozyme concentration of saliva, Lactobacilli and mutans streptococci in saliva and on impressions of teeth and the amount and frequency of sucrose and fibre consumption was determined. The data were analysed using the Kruskal-Wallis, Wilcoxon-Mann-Whitney and Spearman Rank correlation tests. Results: Lactobacilli and/or mutans streptococci were found on all decayed teeth, 98 % of teeth that developed decay, 89 % of filled and 69 % of sound teeth. The best predictor of caries increment was decay. Nine subjects had no caries and no restored teeth with caries (group A); nine had restored teeth with no caries but developed a mean of 8 new decayed surfaces (group B); nine had 4.4 decayed surfaces and developed a further 9.6 surfaces (group C). Group A had fewer filled surfaces (p=0.0237) and a higher flow rate of stimulated saliva (p=0.0140) than B and C. Dietary fibre intake, saliva flow and Lactobacilli and mutans streptococci on teeth, classified 94% of subjects of group A and B correctly, gave a specificity of 100 % and a sensitivity of 89 % and predicted an increase in caries in 17 of the 18 subjects. Conclusions: The percentage of teeth with Lactobacilli and mutans streptococci, salivary flow rate and intake of dietary fibre successfully predicted caries activity in 94% of subjects.