The effect of odours on stimulated parotid salivary flow in humans.

We have previously shown that smell has no effect on resting parotid salivary flow in humans. In this study we investigated the effect of two odours on unilateral parotid salivary flow stimulated by either mastication or mastication with gustation. Neither odour stimulated flow above that elicited by either mastication or mastication with gustation. Removing an odour by sealing the nares has been reported to reduce stimulated parotid salivary flow, suggesting that smell contributes to stimulated salivary flow. However, in the present study, sealing the nares with a nose clip caused a significant reduction in the saliva elicited by an odourless stimulus. Even placing the nose clip over the bridge of the nose without sealing the nares significantly reduced the salivary flow, suggesting that the nose clip itself causes a reduction in stimulated parotid salivary flow. In conclusion, smell has no effect on stimulated parotid salivary flow in humans.