Distance From File Tip to Apical Constriction/Apical Foramen in Relation To Numeric Scale Reading on Display of Two Electronic Root Canal Length Determining Devices

Abstract

Modern Electronic root canal length determining devices (ERCLD) or Electronic apex locators (EALs), claim to determine accurately the tooth length based on the principle of measuring the impedance between the canal fluid and tip of the file with various frequencies. Many manufacturers claim the electronic apex locators (EALs) to exactly display the reading corresponding to the canal parameters. This invitro evaluation compared if the marks ‘‘0.5’’ and ‘‘0.0/APEX’’ on the of display of two EALs Sybron endo Apex ID (SID) and Mini apex locator (MINI) were accurately representing the apical constriction or the apical foramen respectively. Materials and Methods: Sixty extracted, single rooted human teeth were used with alginate model. The electronic length was determined using 2 EALs, at the numeric scale/target ‘‘0.5’’ and ‘‘0.0/APEX’’ mark using K-file (electrode). After cementing the file coronally with type II glass ionomer cement, the apical 3–4 mm was trimmed until the file tip was visible under an operating microscope (X16). Images were captured under Dental operating microscope and the error between electronic length (EL) and actual length (AL) at target interval 0.5 (apical constriction) and 0.0 (major foramen) were analyzed by used Image J software. RESULTS: t-test revealed statistically significant differences between EL determination and AL for both EALs, at “0.0”/Apex, p=0.001, and at 0.5 (apical constriction) p=0.007. CONCLUSION: The numeric meter display of newer generation EALs like Apex ID, represent better correlation with the histologic landmarks and could become a useful guide for inexperienced clinicians, however they do not always indicate the position of the file in the canal.