Objective: Image distortion is an inherent component of rotational radiography. Prediction of the amount of distortion in the horizontal dimension has proven to be most difficult for clinical application. Various regions of the dental arches are distorted differently and this study has attempted to quantify regional distortion. Methods: Multiple images of skulls were made on a Planmecca 2002 orthopantomograph after placing wire fragments 10 mm in length in three areas of the buccal and facial surface of the maxillary arch: 1)across the central incisors, 2) across the canine and first premolar, 3) across the first and second molars. Each skull was aligned as per the manufacturer's recommendation. Thirteen pantographs were taken one at correct alignment (0),6 in front, and 6 behind point 0 at 2 mm increments. Measurements were made of the image wire using a digital micrometer rounded to the nearest 0.1 mm. Results: The regression results predicted that the anterior teeth will have the greatest distortion with an overall average of 0.52 mm distortion for every 2 mm change. Evaluating the forward and backward positions alone showed that skull placement towards the film produced an average decrease in image wire of 0.29 mm/ 2mm. However, distortion was much greater (0.73 mm/2mm increase in image wire)when the skull was moved closer to the tube head. Canine-premolar measurements were more consistent with an overall change of 0.33 mm/2mm, with little variation towards the film or tube head. Molar measurements showed the least distortion with an overall change of 0.16 mm/2mm and again little variation in both directions. Conclusion: Wire distortion with both magnification and minification was greatest in the central incisors followed by the canine/premolar region. Molars were only magnified. Each region of the dental arch will have a specific degree of distortion that may be quantified with further study.

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Back to the 81st General Session of the International Association for Dental Research (June 25-28, 2003)

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