Objective: The aim of this study was to examine the relationships between gland sizes and the flow rate and composition of the unstimulated whole saliva in humans.
Design: In 28 healthy young adults, the sizes of the three major salivary glands were estimated by use of a magnetic resonance (MR) imaging technique. Unstimulated whole saliva was collected for 5 min by the spitting method, and the flow rate and the concentrations of total protein, Na(+) and K(+) and pH were measured.
Results: The estimated sizes of the parotid and submandibular glands showed a significant positive correlation with the flow rate and the secretion rate of total protein in the unstimulated whole saliva, but that of the sublingual glands did not. Concerning the concentrations of Na(+) and K(+) and pH, there were no correlations with the salivary gland sizes.
Conclusions: The results suggest that the larger the sizes of the parotid and submandibular glands, the faster the fluid flow and protein secretion rates in unstimulated whole saliva.