Salivary Protein Concentrations During Infancy From 6-12 Months of Age

Objectives: The present study aimed to prospectively evaluate total salivary protein concentration and flow rates from 6 through 12 months of age.
Methods: The study population consisted of 76 healthy infants. Premature infants were excluded from the study sample. Following medical history, child was examined and stimulated whole saliva was collected and flow-rates measured (mL/min) during the 6^th, 9^th and 12^th months of life. Samples were centrifuged, supernatants separated, lyophilized and stored at -80°C for posterior analysis. Total protein concentration was determined by the bicinchoninic acid assay. Data regarding each child’s weight, oral hygiene habits, diet were obtained. This study was approved by the Ethics Committee of the Federal University of Ceará Medical School. Data were analyzed using Friedman, Wilcoxon signed-rank and Spearman’ rho tests (p<0.05).
Results: There was a significant correlation between the salivary flow rate and total protein obtained in the 6^th (rho=-0.305, p=0.007), 9^th (rho=-0.535, p<0.0005), 12^th (rho=0.883, p<0.0005) months of life. Salivary flow rate significantly correlated with number of teeth during the 9^th month (rho=-0.305, p=0.007). Salivary flow-rates (6^th:0.95±0.28/ 9^th:1.03±0.42/ 12^th:0.79±0.46; p<0.0005) and total protein concentrations (6^th:0.69±0.27/ 9^th:0.62±0.46/ 12^th:1.15±0.49; p<0.0005) differed between months 6, 9 and 12.
Conclusions: Our results suggest that the 2^nd semester of life is marked by an increase in salivary flow rates from the 6^th through the 9^th month of life, followed by a decrease from the 9^th to the 12^th month. During this time, total protein concentration decreases slightly from the 6^th through the 9^th month, and increases significantly thereafter.