removing distortion of periapical radiographs in dental digital radiography using embedded markers in an external frame

objectives : to carry out in vivo and in vitro comparative pilot study to evaluate the preciseness of a newly proposed digital dental radiography setup. this setup was based on markers placed on an external frame to eliminate the measurement errors due to incorrect geometry in relative positioning of cone, teeth and the sensor. methods : five patients with previous panoramic images were selected to undergo the proposed periapical digital imaging for in vivo phase. for in vitro phase, 40 extracted teeth were replanted in dry mandibular sockets and periapical digital images were prepared. the standard reference for real scales of the teeth were obtained through extracted teeth measurements for in vitro application and were calculated through panoramic imaging for in vivo phases. the proposed image processing technique was applied on periapical digital images to distinguish the incorrect geometry. the recognized error was inversely applied on the image and the modified images were compared to the correct values. results : the measurement findings after the distortion removal were compared to our gold standards (results of panoramic imaging or measurements from extracted teeth) and showed the accuracy of 96.45% through in vivo examinations and 96.0% through in vitro tests. conclusions : the proposed distortion removal method is perfectly able to identify the possible inaccurate geometry during image acquisition and is capable of applying the inverse transform to the distorted radiograph to obtain the correctly modified image. this can be really helpful in applications like root canal therapy, implant surgical procedures and digital subtraction radiography, which are essentially dependent on precise measurements.