Evaluation of some electrical methods for objective assessment of oral mucosal dryness

The aim of this study was to evaluate different electrical methods (resistance, capacitance and polarization resistance) for clinical and objective registration of dryness of the oral mucosa. Measurements were performed in the buccal and in the lip mucosa before and every 30 min after injection of 1.0 ml methylscopolamine nitrate submucosally in the labial sulcus in 10 healthy subjects. For comparison, a dental mirror sliding test was used. About 1 h after injection, all three methods showed statistically significant decreases of values in the buccal as well as the lip mucosa except for polarization resistance, which showed such a difference only in the buccal mucosa. The deviations from initial values in the individual subject showed no agreement between measurements with the electrical instruments and oral mucosal dryness assessed with the mirror test. Neither was there any agreement between values registered with the three electrical methods. It seems that these electrical methods are not suitable for registration of individual variations in oral mucosal dryness.