Unstimulated salivary flow rates of young children

Studies on salivary flow rates in human beings have mainly been carried out with adults. The purpose of this study was to determine the unstimulated salivary flow rates of children 4 to 7 years old. In addition, the relative contributions of the variables age, gender, race, height, body weight, dentition status, use of prescription medication, and health status (information obtained from parents) to the unstimulated salivary flow rates of children were also studied.

Data were obtained from children (n = 447) at 2 sites in the United States (site 1, southeast Michigan; site 2, northern Michigan) and at 5 sites in Brazil (site 3, Porto Alegre; site 4, São Paulo; site 5, Belém; and sites 6 and 7, sites in Rio de Janeiro). In northern Michigan (site 2) the participants were cognitively or developmentally disabled, or both. In Rio de Janeiro (site 7), a group of 8- to 12-year-olds served as a control group. Saliva samples were collected for 3 minutes between 9 AM and noon in the spring or summer, and the saliva rate was determined gravimetrically. Data were analyzed by analysis of variance, bivariate analysis, and regression analysis.

The secretion rates at the 7 sites were (in milliliters per minute) 0.19 +/- 0.15, 0.23 +/- 0.28, 0.34 +/- 0.23, 0.48 +/- 0.37, 0.25 +/- 0.27, 0.37 +/- 0.28, and 0.61 +/- 0.34, respectively. There were significant differences among sites (P <.0001). The older group (site 7) had flow rates that were significantly higher than the flow rates of any other group. In addition, children from Michigan (sites 1 and 2) had significantly lower rates than most groups of children in Brazil. Girls had lower unstimulated salivary flow rates than boys did at all the sites, but the differences were not statistically significant. Race was shown not to affect the flow rates. The use of any prescription medication by children in the previous 3 months was associated with lower salivary flow rates than were found in children not using prescription medication. Children who were in good health and who had no previous medical conditions had higher flow rates--but not significantly so. Higher flow rates occurred in children with mixed dentition than in children with primary dentition, although again the differences were not statistically significant. Regression analysis revealed weight to be of significance in explaining the variability of the unstimulated salivary flow rates at 2 sites, height at 1 site, the use of prescription medication at 2 sites, and age at 1 site.

The unstimulated salivary flow rates in children in the northern United States are comparable with those reported for Japanese children, whereas the flow rates of children in Brazil are comparable with those reported for North American and European adults. In addition, none of the demographic variables/parameters tested contributed consistently to the variability of the unstimulated salivary flow rates in children at the 7 sites assessed in this study.