Ex vivo performance of five methods for root canal length determination in primary anterior teeth

Aim To evaluate in a laboratory setting the performance of five methods for the determination of root canal length in primary anterior teeth. Methodology Twenty extracted primary incisors, with at least two-thirds of the root, were used. After access cavity preparation, the teeth were embedded in alginate mixed with 0.9% sodium chloride solution. One operator determined root canal length using tactile sense (T), conventional radiography (RAD), tactile sense and conventional radiography (T + RAD), digital radiography (RDIG) and Root ZX electronic apex locator (EAL) methods. Next, the actual length (AL) was visually determined using a K-file from the coronal reference to the apical foramen or apical resorption level. The measurements obtained through each method were compared to the AL using the intraclass correlation coefficient (ICC) with the limits of agreement calculated with Bland and Altman analysis. The measurements were classified as acceptable (±1 mm from the AL) or not (>1 mm shorter or longer), and the McNemar test was employed for method comparison. Results Differences, limits of agreement and ICCs for each method were respectively EAL = -0.29; -1.02 to 0.44; 0.990; T + RAD = 0.17; -2.18 to 2.51; 0.929; RAD = 0.50; -3.41 to 4.41; 0.818; RDIG = 0.95; -3.76 to 5.65; 0.700; and T = -0.48; -5.59 to 4.64; 0.499. The most accurate and acceptable method was the EAL, followed by the T + RAD. Conclusion The EAL method performed best for root canal length determination in primary teeth.