ABSTRACT
<p><b>OBJECTIVE</b>To investigate the difference between digital periapical film and conventional film in the evaluation of tooth length and root resorption.</p><p><b>METHODS</b>A standard for root resorption in vitro was developed based on 20 extracted upper central incisors. Digital periapical films and conventional periapical films were taken before and after the process of simulating root resorption at six different projection angles respectively. The tooth length and root resorption were measured on these films. The results were analyzed by paired-samples rank sum test.</p><p><b>RESULTS</b>Significant difference on tooth length measurement was found between two types of films on the same projection angle. No significant difference on the length of root resorption calculated on digital and conventional films was found.</p><p><b>CONCLUSIONS</b>The accuracy of the digital periapical film was greater than that of conventional periapical films. The conventional periapical film can still be used in the evaluation of root resorption.</p>