Abstract
Purpose
Electronic foramen locators are widely used to locate the apical foramen (AF), by measuring the electrical impedance between the electrodes (Z E). There is no in vivo study that completely characterizes Z E as a function of frequency and endodontic file tip position. The results of in vivo studies of the impedance Z E and a coefficient that can be used to locate the AF are presented.
Methods
An electronic device was specially built to study Z E . Ten root canals were used in the experiment. The spectral attenuation of Z E was in vivo measured with the endodontic file tip placed at −3.0, −2.5, −2.0, −1.5, −1.0, −0.5 and zero millimeters from the root canal AF. At each file position the spectrum attenuation was modeled. Based on the attenuation models an endodontic spectral attenuation coefficient (ESAC) was defined.
Results
The in vivo results demonstrate that the spectral attenuation of the electrical impedance Z E has an exponential decay in the frequency range of the study. It was verified that ESAC can be correlated to the distance between the endodontic file tip and the apical foramen. The ESAC accuracy was assessed and the results showed that it can locate the AF with accuracy better than 0.5mm.
Conclusions
The spectral attenuation of Z E has an exponential decay for all file tip distances from the AF. It supports the feasibility of ESAC to accurately locate the root canal AF. Moreover, using frequencies steps of one octave makes the implementation of ESAC in an embedded system easier.
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Gamba, H.R., Rambo, M.V.H., Borba, G.B. et al. In vivo characterization of the electrical impedance between the electrodes of the electronic foramen locators. Biomed. Eng. Lett. 3, 170–178 (2013). https://doi.org/10.1007/s13534-013-0100-4
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DOI: https://doi.org/10.1007/s13534-013-0100-4