EVALUATION OF IN-VITRO PROPERTIES OF FILMS OF SALIVA SUBSTITUTES IN CONTACT WITH DIFFERENT SURFACES - A COMPARATIVE-STUDY WITH INSTRUMENTS FOR MEASUREMENTS OF FRICTION AND RHEOLOGICAL PROPERTIES

An instrument based on friction measurement has been developed to eval uate oral mucosal dryness objectively. The purpose of this study was t o compare the friction instrument with instruments measuring in vitro rheologic properties. Measurements were performed against steel and ir reversible hydrocolloid after application of different concentrations of aqueous solutions of carboxymethylcellulose and chitosan lactate. T he results of the measurements were logical, with inversely proportion al values for the friction instrument as compared with values obtained using the instrument measuring theologic properties; that is, increas ed viscosity led to decreased friction values.