Accuracy of the orthopantomogram in assessment of tooth length in orthodontic patients.

The orthopantomogram (OPG) provides as assessment of root length and characteristics before orthodontic tooth movement. This study determined the accuracy of the OPG in assessing tooth length. Investigators compared the radiographic and actual tooth lengths in permanent first premolars indicated for orthodontic extractions. Results showed that the mean lengths measured from OPG were consistently higher than the actual lengths by 22% (p < 0.001) for maxillary teeth and by 1% for mandibular teeth. This study found that there is elongation of root images in OPG.