A study in vitro on accuracy of two kinds of electronic apex locators in canals with destroyed apical constrictions

Objective:To compare with the accuracy of Propex and Raypex5 electronic apex locators in canals with destroyed apical constrictions.Methods :Apices of 20 extracted human teeth with single root canal were cut off and the apical constrictions were destroyed to different diameters by a cone shaped diamond bur.Apical foramen were located with Propex and Raypex5 electronic apex locators in models and the results and the accuracy of the two in different diameter ranges of apical foramens were compared.Results:On condition of the apical constrictions destroyed,the differences between actual root canal length and measured root canal length of two electronic apex locators in the same root canals were no statistically significant(P0.05),and the differences between actual root canal length and measured root canal length of the same electronic apex locators in root canals with different diameter ranges of apical foramens were statistically significant(P0.05),and the accuracy of two electronic apex locators decreased with the increase of diameters of apical foramens.Conclusion:On condition of the apical constrictions destroyed,the accuracy of Propex and Raypex5 was influenced by diameters of apical foramens.Clinically the measurement error should be considered when Propex or Raypex5 was used to locating apical foramens in roots with destroyed apical constrictions or not well developed apices,and apical foramens locating should be done by electronic apex locators combined with other methods.