The effect of different needle-insertion depths on the accuracy of the Root ZX II and Root ZX mini apex locators in the presence of various irrigants

The aim of the present study was to evaluate the effect of different needle-insertion depths on the accuracy of the Root ZX II and Root ZX mini apex locators in the presence of various irrigants. Ninety extracted single-canal human teeth were used in nine experimental groups. The coronal one-third of the canals was preflared, and the length to the major foramen was determined visually under a microscope. The teeth were embedded in an alginate model. NaOCl concentrations of 5.25%, 2.60%, and 2.00% chlorhexidine with three endodontic needles (21, 25, and 30 gauges) were delivered into the root canals of teeth in each group. Electronic length was determined with both devices using K-files of size 10. The results obtained with electronic apex locators were compared with the corresponding actual length. A multivariate linear regression model was used to determine the variables influencing the accuracy of the Root ZX II and Root ZX mini apex locators. Irrigant solution concentrations had no effect on the accuracy of the measurements with these locators (P = 0.83). The statistical analysis of the results showed EAL accuracy to be 100% for both Root ZX and Root ZX mini, within a tolerance of ± 0.5 mm. Data were analyzed by ANOVA. Multivariate linear regression model demonstrated that needle-insertion depths influenced the electronic measurements (P = 0.05), while the concentrations of irrigants did not influence the results. Under the conditions of this ex vivo study, needle-insertion depths influenced the electronic measurements.