Determination of the root canal length using impedance ratio method.

Accurate root canal length determination is crucial for successful endodontic procedure where the root canal of the tooth is opened, cleaned and sealed. Impedance method is becoming a standard method for determination of the position of apical foramen. Current devices rely on determination of apical foramen from the ratio of impedances measured at two or more frequencies. The investigation is aimed in determination of optimal parameters for determination of apical foramen with best possible accuracy. The investigation has revealed an optimal ratio of 0.79 determined at frequencies 1 kHz and 500 Hz with a standard deviation of about 1 mm. [ABSTRACT FROM AUTHOR]