Low-frequency dielectric properties of the oral mucosa

Low-frequency (<= 1 MHz) electrical conductivity and permittivity spectra of the oral mucosa were reconstructed from impedance measurements at various regions (tongue, buccal mucosa, hard palate) of the oral cavity. Impedance magnitude and phase were measured with the HP4284A LCR meter in the frequency range from 30 Hz to 1 MHz. Bipolar intraoral measurement probe was used. In order to obtain conductivity and permittivity spectra from measured impedance data, the geometry factor of the probe (cell factor) was determined theoretically. Namely, numerical modeling using the finite-element method was used to calculate the geometry factor. The FEM model was also used to study the sensitivity field of the probe and the penetration depth. The results show typical dispersion characteristics observed in alpha-, and beta-dispersion range of biological tissues. Possibilities of correcting electrode polarization, which causes error at lower frequencies are considered.