Do panoramic radiographs provide a true assessment of the mesiodistal root relationship of adjacent teeth during orthodontic treatment?
Noting that correct tooth position in three planes is a key objective of orthodontic treatment, four private practice dentists from Switzerland compared panoramic images with cone-beam CT images of 235 interdental sites in 22 patients to find out (American Journal of Orthodontics and Dentofacial Orthopedics, March 2010, Vol. 137:3, pp. 389-392).
They took panoramic images of the patients -- who all had fixed appliances in both arches and were near the end of treatment -- before debonding. When the pano images indicated that the roots of adjacent teeth were touching, the researchers then used cone-beam CT to verify the root relationships.
Of the 235 interdental sites imaged using both panoramic x-rays and cone-beam CT, 47 areas showed contact between adjacent roots in the pano images, while the cone-beam CT images showed true contact in only five of these areas. Thus only 11% of the diagnoses based on panoramic images were true-positive, while the rest were false-positive, the researchers noted.
In all, 188 sites showed no contact in the panoramic images; these findings were confirmed by cone-beam CT.
While panoramic imaging has high sensitivity and relatively high specificity to detect adjacent roots touching each other, root contacts are often overestimated when evaluated using this method, the researchers concluded.
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