Electric impedance measurements at six different anatomic locations of macroscopically normal human oral mucosa.

We have used an electric impedance technique to explore the properties of the oral mucosa at various sites in the normal mouth. Investigations were performed on 26 healthy non-smoking subjects at 12 test areas, representing a range of mucosal types. Electric impedance spectra were measured in the frequency range 1 kHz to 1 MHz at five depth penetration settings of the instrument, and four indices were calculated for each depth. Statistically significant differences in the indices were found between most of these locations but not between contralateral sites at a similar position. The differences between some areas were considerably greater, and the differences between contralateral sites were smaller, than those encountered in the skin. Our results suggest that the choice of site for investigation of the oral cavity is more critical than with experimentation on the skin and that cognizance of this fact makes the oral cavity readily available for studies by the impedance method.