Systematic analysis of gingival state and salivary variables as predictors of caries from 5 to 7 years of age.

The aim was to assess the caries predictive ability of gingival state, salivary counts of lactobacilli and S. mutans, salivary secretion rate and buffer capacity of the saliva from the ages of 5 to 7 yr. The material comprised 105 children who were examined once a year. All available screening levels were systematically tested for the single variables as well as for combinations of two or three variables. The screening levels were set where the highest possible sensitivity and specificity were reached simultaneously. The predictive values for positive and negative tests were then calculated. The S. mutans count turned out to have the best combination of sensitivity (0.41) and specificity (0.83). The single variables gingival state and S. mutans had constant screening levels, while the values for lactobacilli and buffer capacity varied. The saliva secretion rate could not be measured at 5 yr of age. Systematic analyses of predictive ability of combinations of two or three variables were then performed and did not result in any clinically significant improvements of the predictive ability. The observed low predictive ability might be explained by the fact that 1) many children changed their habits during the period of investigation and 2) they were examined and treated once a year according to their individual needs, which meant variations in conservative as well as in preventive treatment.