Comparing the Accuracy of Conventional (E-Speed) and Digital (CMOS) Radiographies in Estimation of the Working Length of Root Canals of Mandibular Molar Teeth

Working length determination is one of the most important factors in successful root canal treatment; therefore, this study was carried out to compare conventional (E-speed) and digital (CMOS) radiographies in determining the working length of the root canals of mandibular molar teeth.
In this ex-vivo study, 25 permanent mandibular double-root first molar teeth were selected and then access cavities were prepared. In order to determine the real working length of the roots, the number 15K-files were transferred into the canals. After placing each sample in the socket of the teeth, conventional and digital radiographies were performed and the distance between the leveled cusp tip and the file tip were measured in conventional radiography and CMOS images by a caliper with an accuracy of 0.01mm and software, respectively. The data was analyzed using Greenhouse-Geisser, paired t-test and simple linear regression.
According to the findings of this study, there was no significant difference between the accuracy of conventional radiography and digital radiography (CMOS) in determining the working length of the root canals of mandibular first molar teeth with less than 25˚ curve (p>0.05). However, in roots with more than 25˚ curve, the working length of root canal was higher in the digital radiography (CMOS) compared to the conventional radiography (E-speed) (p=0.001and p=0.004, respectively).
Based on the results of this study, it can be concluded that digital CMOS radiography can be used to measure working length of root canals with mild curvature. However, in teeth with high curvature, it would be better to use conventional radiography to estimate the working length.