Salivary flow rates and salivary film thickness in five-year-old children.

The flow rate of unstimulated whole saliva, the volume of saliva in the mouth before (VMAX) and after (RESID) swallowing, and the surface area of the mouth were measured for determination of the average thickness of the salivary film in five-year-old children with primary dentitions. In 30 subjects of each gender, RESID was calculated from the potassium concentration in unstimulated saliva by a dilution technique. VMAX was calculated as the total of RESID plus the volume normally swallowed (the unstimulated salivary flow rate divided by the swallowing frequency). From these children, ten subjects of each gender who had no missing teeth were selected, and impressions were taken for determination of the surface area of the mouth. Aluminum foil, of known weight per unit area, was adapted to the stone models of different regions of the mouth, and the surface areas were calculated from the weights of foil. The unstimulated salivary flow rate was 0.22 +/- 0.14 mL/min, the mean values of RESID and VMAX were 0.38 +/- 0.11 mL and 0.50 +/- 0.15 mL, respectively, and the mean total surface area of the mouth was 117.6 +/- 7.6 cm2. There were no significant differences in these values due to gender. The average thickness of the salivary film in the mouth was calculated to vary between 0.06 and 0.09 mm. Although the values of salivary flow rate, RESID, and VMAX were much lower than those reported for adults, the average thickness of the salivary film was very similar to that in adults.