RootZX or TriautoZX are examples of which type of apex locator:
Multiple-frequency apex locator: A newer apex locator was introduced (Root ZX by J. Morita, Japan) that uses two wavelengths: one high (8 kHz) and one low (400 Hz) frequency. They assess the apical terminus by the simultaneous measurements of the impedance of two different frequencies that are used to calculate the quotient of the impedances. The other apex locators which follow the similar principle include Propex II (Dentsply Maillefer;), Elements Diagnostic EAL (Sybron Endo), Formatron D 10 (Parkell Co.) and the Apit 7 (Osada).
Resistance based apex locator.
Multiple frequency apex locator.
High-frequency apex locator.
Dual frequency apex locator.