In-vitro comparison of the different apex locator at different sizes of apical opening

The purpose of this study was to compare the effectiveness of different electronic apex locators in determining the working length in both closed and different sizes of apical openings. For this study 80 extracted human maxillary central and lateral incisors with mature apices were used. Actual working length measurement was performed by using a x6 loupe. The working length was considered as 1mm short of the point where a size 10 K-file tip was visible at the apex. The teeth were divided into four groups (n=20). First group (G 0) included teeth with mature apices. Root canals of the other groups (G 34, G 59, and G 84) were enlarged to apical sizes of 0.34, 0.59 and 0.84 mm. All teeth were embedded in alginate filled molds for electronic measurements. Electronic measurements were performed with Raypex 6, Apex ID and Root ZX mini according to the manufacturers' instructions. Measurements were performed 3 times and their averages were recorded. The actual lengths and electronic measurements were statistically analyzed. No statistically significant difference was found between the actual length and electronic measurements in teeth with closed (untouched) and enlarged apices regardless of the apex locator used. All 3 devices are suitable for clinical use in both open and closed apices. Keywords: Electronic Apex Locator, Apical Foramen, Actual Working Length