The Accuracy of Panoramic Radiography in Assessing the Mesiodistal Angulations of Teeth

Nowadays, the use of panoramic radiographs for evaluation of uprighting and root parallelism, after the closure of spaces and before the debanding of fixed appliances, often been accepted, and the use of radiography to evaluate the results at the end of orthodontic treatment is discussed.It is not clear whether panoramic radiography reflects the exact mesiodistal position of the maxilla and mandible tooth roots. We had 10 patients with class I molar relationships, and took an alginate impression from both jaws then poured that with moldano plaster.To determine the long axis of the teeth, orthodontic wires (0.7) Parallel to the long axis of the teeth, (on diagnostic casts) was used. To take a panoramic radiography from casts, Panoramic imaging device “Planmeca 2002 CC” with 4mA and 60kvp was used.Photo was taken from Casts and Panoramic radiographs, then the angles between the wires and the reference line, were measured by the Autocad 2005 software, and the values related to casts and panoramic radiographs, were compared. Significant percentage of achieved angles of the panoramic images (71.2%), statistically,were not in the acceptable range(±2 degree). Generally, the lowest accuracy of panoramic radiography in assessment of mesiodistal angulation of the teeth was in the lower lateral incisor region. (ICC=-0.237). Also, the differences between the actual angles and radiographic angles in maxilla, was considerably less than in mandible. This study aimed to determine the accuracy of panoramic radiography in the assessment of mesiodistal angulations of the teeth. Dentists should act cautiously in making clinical decisions for requirements of angle adjustments, according to panoramic radiograph findings, with the knowledge of permanent distortion panaoramic image.