In Vitro Precision of the E-PEX Electronic Apex Locator Compared to the Root ZX II in Various Embedding Media

Abstract

Introduction: One of the challenges of non-surgical root canal treatment (NSRCT) is determining the working length of the canal which indicates the end point of root canal preparation and obturation. The development of the Electronic Apex Locator (EAL) has helped the clinician to determine the location of the apical foramen, and hence the working length, when performing NSRCT. Objectives: The goal of this study is to determine the accuracy of a new EAL, the E-PEX, and compare it to a commonly accepted EAL, the Root ZX II in the presence of different embedding media. Materials and Methods: Forty-two extracted single rooted teeth were used in the study. The distance from a coronal reference point to the apical foramen measured after sectioning the crown. First, the crown length was determined by direct visualization of a #15 k-file as it exited the major foramen via dental operating microscope (DOM). Fourteen teeth were then mounted in each embedding media, alginate, 2% agar-agar and bovine skin 6% gelatin and measurements for the apical foramen were made using the Root ZX II and E-PEX. The accuracy of measurements from the different EAL’s were compared. Results: The difference between E-PEX and Root ZX II regarding deviation from the direct measurement was not statistically significant in agar (p=0.857) or alginate (p=0.923), but for bovine, the difference was significantly larger for E-PEX than for Root ZX II (p=0.042). The type of embedding medium affected the difference from the direct measurement, with smaller deviations observed in bovine compared to agar (p=0.004) and alginate (p=0.008). 100% of the teeth had measurements within 0.5 mm of the direct measurement when using alginate and bovine embedding media. In agar, two teeth had measurements exceeding 0.5 mm from the direct measurement for E-PEX, while Root ZX II had three teeth exceeding 0.5 mm. No significant difference was found between E-PEX and Root ZX II in the percentage of teeth measured within 0.5 mm of the direct measurement (p=1.00 for alginate and bovine, p=0.317 for agar). Conclusion: There was no statistically significant difference between the E-PEX and Root ZX II in the percentage of teeth with measurements within ±0.5 mm of the direct measurement, with p-values of 1.00 for both alginate and bovine models, and 0.317 for the agar model.