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Dielectric Properties of Dentin between 100 Hz and 1 MHz Compared to Electrically Similar Body Tissues

Electrical properties of many human tissues have already been measured. However, there is insufficient information about dentin dielectric behavior that can be used for modeling the tooth impedance in the frequency range used by most electrical apex locator devices. Instead, properties of a human cortical bone [1] or own measurements at one or two frequencies were used when needed [2]. The goal of this study is to measure dielectric properties of a human tooth dentin in frequency range of 100 Hz to 1 MHz and to compare them with available data. The measurement was performed on a dentin sample cut out of an extracted human tooth. Dentin sample was electrically interfaced to the measuring equipment using two cotton swabs moisten in physiological saline solution. Conductivity and relative permittivity were calculated at each measured frequency, and the results compared to the dielectric properties of a few similar tissues according to [3] and [2]. The best match was observed with the dielectric properties of a cortical bone according to [3]. However, about 4 times of error was observed in conductivity. Additionally, an excellent agreement of conductivity was observed for dielectric properties used in [2], nevertheless relative permittivity differed about 5 times. Using these data could produce a significant error in calculation of tooth impedance.

Dentin impedance; Dielectric properties of dentin; Root canal length measurement

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