However, according to our knowledge there is no wrıtten data comparing the in vivo WL measurements of different EALs under different circumstances using micro-CT. ( 5) investigated the accuracy of two apex locators in different anatomic variations using micro-CT. ( 4) determined the location and dimension of the AC in molar teeth. The AC can be determined by evaluating the canal cross-sectional area and not by locating the minor diameter in one longitudinal section ( 22). With the aid of micro-CT, the AC can be determined accurately without destruction of the tooth structure ( 4). The use of micro-computed tomography (micro-CT) gives opportunity to view detailed 3-dimensional (3D) analyses of extracted teeth’s internal anatomy with the high-resolution radiographic scannings of the specimen ( 18- 21). However, the accuracy of EALs may be affected by some conditions such as periapical lesions, immature apex formation, apical foramen size, electrical conductivity of the intracanal fluid (such as, irrigants, pulp) ( 12, 14- 17). There are several investigations about the accuracy of EALs in different environments ( 9, 11- 14). Raypex 5 (VDW, Munich, Germany) is a frequency-based EAL, and it measures the impedance at two different frequencies (0.4 kHz and 8 kHz), but uses only one frequency at each time interval and the measurements are based on mean square values of signals ( 10). Propex Pixi (Dentsply Maillefer, Ballaigues, Switzerland) is a recently introduced multi-frequency EAL, Mini Root ZX (J Morita Corp., Tokyo, Japan) is another contemporary EAL that uses the ‘ratio method’. There are several methods for determination of the WL such as assessment of preoperative radiographs, tactile sensation and electronic apex locators (EALs) ( 7, 8).Įlectronic apex locators (EAL) provide reliable and accurate results in working length determinations ( 9). However, the location of AC is difficult due to the anatomical variations that could vary depending on various factors ( 4- 6). Several studies consider the AC of the root canal system as the end point of instrumentation or obturation processes ( 2, 3). In the root canal anatomy, apical constriction (AC) is the narrowest diameter of the root canal system ( 2, 3). However the end point of instrumentation is still debated ( 1).
In endodontology, the working length (WL) is defined as the distance from a coronal reference point to the point at which canal preparation and root canal filling should terminate.
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