These figures are then analysed in

These figures are then analysed in a procedure to determine the location of the minor diameter (constriction) (Welk et al. 2003). The principle behind this device, however, is similar to the impedance ratio-based ERCLMDs. It detects the canal terminus by determining a sudden change in the dominant characteristic (capacitive or resistive) of the impedance. Welk et al. (2003) compared the accuracy of an impedance ratio-based ERCLMD (Root ZX
) and the Endo Analyzer and found that the mean distance between the electronically located canal terminus and minor diameter was 1.03 mm for the Endo Analyzer and 0.19 mm for the Root ZX
; the ability of the devices to locate the apical constriction was 34.4 and 90.7% of cases respectively. Pommer et al. (2002) evaluated the effect of pulp vitality on the accuracy of the AFA Apex Finder
7005 and reported that the difference between measurements in canals with vital or necrotic pulps was significantly different and concluded that the AFA Apex Finder
was more accurate in vital cases.