Flow rate, amylase activity, and protein and sialic acid concentrations of saliva from children aged 18, 30 and 42 months attending a baby clinic.

Whole-saliva samples were collected under slight suction from children enrolled in a dental-care programme at a baby clinic and analysed according to sex. The children were allocated to three age groups: 18, 30 and 42 months. No distinct sex difference was found for flow rate; there was a statistically non-significant tendency for an increased rate in females. In the males the flow rates of the 30- and 42-month groups were higher than those of the 18-month group; a similar result was obtained when findings for both sexes were combined. There was no difference in salivary protein concentration between the sexes or the age groups. Amylase activity increased significantly in males from 18 to 30 months of age. Sialic acid concentration (micromol/mg protein) showed a sex difference for the 18-month group; it was 38% higher in males than in females, and 48% higher than in the males of 42 months. This trend toward a reduction in sialic acid concentration with age suggests a reduced synthesis and secretion of glycoproteins.