Temperature dependence of the electrical resistance of sound and carious teeth

Temperature variations are expected to influence measurement error in electrical resistance of teeth. It was the aim of this study to determine the changes in electrical behavior of extracted human teeth due to temperature changes in the range of room temperature to intra-oral temperature. Nine extracted teeth were selected, and the occlusal or an approximal surface was chosen for measurement. Carious involvement of the surfaces ranged from sound to cavitated. Electrical impedance spectroscopy sweeps in a frequency range of about 100 kHz to 10 Hz were completed at selected temperatures between 22 degrees C and 40 degrees C. After fitting the data to equivalent circuits that yielded parameter values for components of the equivalent circuit, we calculated the dc bulk resistance (R-b). The temperature dependence of R-b of the surfaces with different carious involvement was very similar, and the mean drop of R-b from 20 to 35 degrees C was 45% (SD 2%). It was concluded that the electrical resistance of sound and carious tooth surfaces is inversely related to temperature.