Influence of root canal taper on the measurement of two different electronic apex locators.

Background: This research aimed to analyze the influence of root canal taper on the accuracy of two Electronic Apex Locators (EALs).

Material and methods: Twenty-five disto-vestibular roots from extracted human upper molars belonging to the tooth bank were used in this study. To determine the File Position (FP), access was made using a spherical diamond tip #1014, and the crowns were sectioned using a diamond tip #3080. The initial anatomic file used was a size K #10, which was introduced into the root canal until its tip was visualized (foraminal patency) with the aid of a clinical microscope (16X magnification). Teeth without foraminal patency and calcifications were excluded from the study. Odontometric readings were performed using two different EALs (Root ZX II and Romiapex A-15), considering the electronic reference point 0.0 (apex) for each device. All measurements were taken in triplicate, and the arithmetic mean of the three values was used. Digital calipers were used to record the measurements, which were then entered into an Excel spreadsheet. After visual verification using file K #10, the canals were instrumented with a #25.01 file to standardize the apical region, then successively instrumented with files #25.02, #25.04, #25.06, #25.08, #25.10, and #25.12, with electronic odontometry checked after each instrumentation using #25.02. Measurement 0.0 was adopted, with error margins of ±0.5 and ±1.0. Discrepancies between visual and electronic readings were statistically analyzed using ANOVA and Bonferroni tests, with significance considered when P<0.05.

Results: Using the 0.0 mark and a ±1.0 error margin, it was observed that readings from the devices were similar in canals with different tapers (P>0.05), showing a tendency towards underestimation. However, when using the measurement variation margin of ±0.50, a statistically significant difference was found in the Romiapex A-15 group (P=0.0248) when comparing the results of the two EALs.

Conclusions: Therefore, it was concluded that the canal taper did not significantly influence the accuracy of the evaluated EALs, using the reference point 0.0. When using the ±0.5 variation margin, the Romiapex A-15 device showed greater accuracy, and finally, at the ±1.0 error margin, both EALs exhibited excellent precision. Key words:Endodontics, Odontometry, Eletronic Apex Locator, Root Canal Preparation.