Evaluation of electrical impedance ratio measurements in accuracy of electronic apex locators
김필종, 김홍기, 조병훈,
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김필종 ( Kim Pil-Jong ) - Seoul National University School of Dentistry Biomedical Knowledge Engineering Laboratory
김홍기 ( Kim Hong-Gee ) - Seoul National University School of Dentistry Biomedical Knowledge Engineering Laboratory
조병훈 ( Cho Byeong-Hoon ) - Seoul National University School of Dentistry Department of Conservative Dentistry
KMID : 1034420150400020113
Abstract
Objectives: The aim of this paper was evaluating the ratios of electrical impedance measurements reported in previous studies through a correlation analysis in order to explicit it as the contributing factor to the accuracy of electronic apex locator (EAL).
Materials and Methods: The literature regarding electrical property measurements of EALs was screened using Medline and Embase. All data acquired were plotted to identify correlations between impedance and log-scaled frequency. The accuracy of the impedance ratio method used to detect the apical constriction (APC) in most EALs was evaluated using linear ramp function fitting. Changes of impedance ratios for various frequencies were evaluated for a variety of file positions.
Results: Among the ten papers selected in the search process, the first-order equations between log-scaled frequency and impedance were in the negative direction. When the model for the ratios was assumed to be a linear ramp function, the ratio values decreased if the file went deeper and the average ratio values of the left and right horizontal zones were significantly different in 8 out of 9 studies. The APC was located within the interval of linear relation between the left and right horizontal zones of the linear ramp model.
Conclusions: Using the ratio method, the APC was located within a linear interval. Therefore, using the impedance ratio between electrical impedance measurements at different frequencies was a robust method for detection of the APC.
키워드
Canal length; Electrical impedance; Electronic apex locator; Endodontics; Impedance ratio
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