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

BACKGROUND AND AIM: 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. METHODS: 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. RESULTS: 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. CONCLUSION: Under the conditions of this ex vivo study, needle-insertion depths influenced the electronic measurements.