In vitro comparison of three different image receptors for determining the length of endodontic files

Abstract Background/purpose The aim of this study was to evaluate the accuracy of endodontic file length measurements of E-speed radiographs, Digora storage phosphor plates, and Schick charge-coupled device sensors, with a secondary aim of assessing the influence of image enhancement on the measurement accuracy. Materials and methods Forty-seven extracted mandibular first premolar teeth were selected. ISO size 8, 10, and 15 files were inserted into each canal, and the files were fixed when the tip was seen at the apical foramen. The teeth were mounted in acrylic blocks and exposed using E-speed films, Digora storage phosphor plates, and Schick charge-coupled device sensors. Two radiologists and two endodontists measured the length of each file between the file stopper and tip on each image. Measurements were carried out on original and magnified images as well as on revealer images for Schick CDR. The actual lengths of the files were measured using a calipers to the nearest 0.01 mm and served as the “true length”. Repeated measures analysis of difference and Tukey honestly significant difference tests were used to analyze the data (P  Results E-speed films were superior to digital systems for the measurement accuracy of the size 08 file (P   0.05). The most accurate results were obtained with the size 15 file regardless of the image receptor (P > 0.05). Conclusion Size 15 or larger files should be used for endodontic working length determinations. Revealer images gave equivalent results with E-speed films and may be utilized for determining the file length of size 10 files.