1976 Volume 1 Issue 2 Pages 88-102
The basic problems, that are derived from the measurelnent of electrical impedance of gingiva, were systematically investigated in various experimental conditions. Especially, the A. C. characteristics of metal(Ag-AgCl), conductive rubber and cotton-wick electrodes(φ=5.0㎜)were examined over the frequency range of 3 Hz to 30 KHz. After determination of the intrinsic impedance and reactance ratio of the electrodes, analyses of the pressure effects and time courses of variation in impedance value were carried out in an equivalent model circuit and in animal gingiva. The results obtained in this paper indicated that the value of total impedance gradually decayed wlth increase in pressure applied to the electrode and the metal and conductive rubber electrodes were very unstable and showed poor reproducibility. These decreasing ratio in impedance were more than 20% in those electrodes and less than 5 to 8% in the cotton-wick electrode. With all our data, the latter electrode was one of the most suitable for the measurement of impedance in mucous membrane such as gingiva. A preliminary experiment indicated that the total impedance value was about 5.5 to 6 KΩ in human gingiva.
