Abstract: PURPOSE: To compare the accuracy of measuring root canal working length with two different electronic apex locators and digital X-ray. METHODS: Ninety patients treated from January 2015 to June 2016 were selected, 232 root canals in total were randomly divided into 3 groups: X-ray group, Raypex5 group and i-root group. The accuracy of working length measured was assessed according to the filling quality of related main tips. The data were analyzed with SPSS19.0 software package for Chi-square test. RESULTS: The success rates for root canal filling of X-ray group, Raypex5 group and i-root group were 88.5%, 92.9% and 96.1% respectively with no significant difference between 3 groups (P>0.05). The success rates for root canal filling of molar teeth, premolar teeth and front teeth were 92.5%, 96.6% and 95.2% respectively with no significant difference between the 3 groups (P>0.05). CONCLUSIONS: The clinical effect of Raypex 5 and i-root electronic apex locators for working length measuring is similar to that of conventional X-ray, but the use of electronic apex locators can avoid unnecessary ionizing radiation and improve clinical efficiency.

Key words: Root canal treatment, Working length, Electronic apex locators