Evaluation of Electrical Equivalent Circuits of a Tooth: Comparison of Circuits with Resistors and Capacitors and the Circuit with a Constant Phase Element

摘要

During the endodontic treatment electronic devices called apex-locators are used to determine the root canal length of the tooth. Apex-locators measure the electrical impedance of the root canal and display the position of the electrode inside the canal. In order to better understand physical phenomena inside the root canal and to improve the measurement procedure, tooth is modeled by an electrical equivalent circuit. In this paper eleven different electrical equivalent circuits comprising of frequency independent resistors and capacitors are examined and compared to a simple equivalent circuit which contains a constant phase element. Impedance measurements were performed in vitro on extracted tooth immersed in alginate dental impression material. Quality factors are calculated to compare the fit quality and parameter utilization efficiency for each considered electrical equivalent circuit. We have found that five-element circuit shows superior performance in both fit quality and parameter efficiency among circuits comprising of resistors and capacitors. However, it can not compete with a simple equivalent circuit that contains a constant phase element.