For the Root ZX mini apex locator, the file was introduced into the canal until the “apex” on the unit’s display was flashing with an accompanying solid audible sound, the file was then retracted to the level of the flashing bar between the “apex” and the“1.0” mark at the level of the small triangle on the right side of the display and a “00” reading was visible on the numeric display to the see more left. The file was then removed and the distance between the file tip and the silicon stop was measured and recorded as the EL. For the Mini Apex Locator, the file was advanced into the canal until orange LED light at the “Past Apex” mark is turned on, the file was then withdrawn until the green LED light at the “Apex” mark is turned on combined with the distinctive audible signal. The file was then removed and the distance between the file tip and the silicon stop was measured and recorded as the EL. For the Root ZX, the file was introduced into the canal until the “apex” on the unit’s display was flashing combined with a solid audible sound, the file was then retracted to the level of the flashing bar between the “apex” and the“1.0” mark with a flashing tooth on the side. The file was then removed and the distance between the file tip and the silicon stop was measured and recorded as the EL. All readings were considered correct when the distinctive features for each device indicating that the desired working length reference point has been reached were stable for at least 5 s. A single operator performed all the measurements. Each measurement was performed twice and the average was recorded. The recorded EL was compared with AL by subtracting the AL from EL. A positive value indicates that the EL exceeds AL (long) and a negative value indicates that EL measurement is short of the AL. In addition, EL measurements were classified into three categories based on the EL file tip position relative to the AL reference point: “correct” (AL ± 0.5 mm), “long” (>0.5 mm from AL), and “short” (<−0.5 mm from AL). The data were analyzed using ANOVA followed by Schafee post hoc (p < 0.05) for difference in means; and using Chi-square for differences between categories of EL file tip position relative to the AL reference point. The results for the mean difference between EL and AL as well as the number and percentage of readings in each of the categories that are based on the EL file tip position relative to the AL reference point in the presence of the six irrigation solutions are presented in Table 1 for the Root ZX mini, Table 2 for the Mini Apex Locator, and Table 3 for the Root ZX. There were no statistically significant differences for the mean difference between EL and AL in the presence of different irrigation solutions for the Root ZX mini (p = 0.75), the Mini Apex Locator (p = 0.