Longitudinal study of salivary IgA in children from 1 to 4 years old with reference to dental caries.

The concentration of salivary IgA was measured and clinical examinations performed annually in 39 children over a period of 36 months. The age of the children ranged from 1 to 4 yr during the observation period. The geometric mean value of salivary IgA increased rapidly between the age of 1 and 2, from 0.021 g/l (log mean - 1.68 +/- 0.33) to 0.052 g/l (log mean - 1.28 +/- 0.24). After this age the mean level of salivary IgA remained fairly constant during the observation period. When the study population was divided into two groups: the caries-free group and the caries-susceptible group, it was found that in the caries-free group the mean salivary IgA value increased rapidly during the second year of life, then more slowly after the age of 2. In the caries-susceptible group the increase in the mean value between the ages of 1 and 2 was marked and at the age of 2 the values were significantly higher compared to those of the caries-free group. The concentrations did not, however, remain high, but fell to lower level and at the age of 4 there was a marked overlap in the values of the groups.