Microorganisms on teeth, saliva flow and fibre predicts caries activity

The number of decayed and filled tooth surfaces, microbiological counts, salivary buffering capacity and flow rate and dietary sucrose can be used to select caries prone subjects. Objectives: This study determined whether conventional tests combined with the presence of microorganisms on teeth could predict caries Methods: Twenty-seven dental students were examined for caries susceptibility. The number of decayed, missing and filled surfaces was counted initially and after 4 years. At the start of the study a plaque index, salivary flow and buffering capacity, sucrose intake, fibre consumption and Lactobacilli and mutans streptococci in saliva were investigated. Thereafter impressions were taken of the teeth with a hydrocolloid impression material mixed with broth, incubated and examined for mutans streptococci and Lactobacilli. The data were analysed using the Kruskal-Wallis, Wilcoxon-Mann-Whitney and Spearman Rank correlation tests. Results: The best predictor of caries increment was decay. Nine subjects had neither caries nor restored teeth with decay (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 an additional mean of 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 groups B and C. Lactobacilli and mutans streptococci were found on all decayed teeth, 98 % of teeth that developed decay, 89 % of filled and 69 % of sound teeth. Fibre intake, saliva flow and Lactobacilli and mutans streptococci on teeth gave a specificity of 100 %, a sensitivity of 89 % and successfully predicted an increase in dental caries in 94% of subjects. Conclusions: This longitudinal study shows that Lactobacilli and mutans streptococci on teeth, saliva flow and fibre intake can successfully predict a caries increment.