RESUMO
Successful root canal therapy is related to cleaning, shaping and obturation of the root canal system with a proper limited working length. Therefore, these are achieved by knowledge of root canal anatomy and radiograph images. Current radiographic techniques are elementory methods. With the advancement of computer technology, and due to limitations that exist, in this recent decade significant attention has been given to digital radiography. Software programs for digital radiographic systems, such as magnification of different images is a tool assistant for digital systems in increasing precision. The purpose of this study was to compare different magnifications of digital radiography to determining canal length. In this experimental in vitro study, 30 human anterior teeth were selected and cleaned in detergent. The actual working length was measured with a N.15 file. Then the teeth were casted and the files were inserted in canals in 3 different positions, proper, under and over. Ninety images of the teeth in three magnifications were made and working length was evaluated by three endodontists randomly. Then the Friedman test was used for statistical analysis. After statistical analysis, the results showed that there was no significant differences between the groups. But there is significant difference in 2X magnificantion of under working length to real working length. In conclusion, it can be stated that magnification of digital radiography can not be helpful in determination of working length especially in under position