A new device for measuring oral mucosal surface friction--reference values

Sialometry and dryness measurements performed with a sliding friction instrument were carried out in healthy subjects and patients with oral dryness due to salivary gland diseases. The salivary flow rates were within normal reference values. The mean friction value in the healthy population was 1.73 +/- 0.37 in the lip mucosa and 1.25 +/- 0.31 in the buccal mucosa and did not show any age or sex differences. In the group of patients with salivary gland diseases, none produced measurable amounts of resting saliva but a few of them did produce small amounts of paraffin wax chewing-stimulated saliva. The friction instrument proved to register lubrication produced even by these very small amounts of saliva.