Facial and dentoalveolar structure and the prediction of apical root shortening.

The purpose of the present study was to determine whether pretreatment measures of facial and dentoalveolar structure can be used to predict apical root shortening liability. Four hundred patients were randomly selected from the files of the Orthodontic Clinic at the Saint Louis University Health Sciences Center. Pretreatment and posttreatment periapical radiographs of maxillary central incisors and pretreatment lateral cephalometric radiographs were traced and measured. A large amount of apical root shortening was found in 2% of the sample. A relationship that was weak but highly significant statistically (r = 0.335; p < 0.01) was found between the amount of apical root shortening and the duration of active treatment. Several measures of dentoalveolar structure were also statistically significant. However, these measures did not account for enough of the observed variability to be clinically useful as a predictor. In the absence of a history of trauma or pretreatment signs of root resorption, pretreatment facial and dentoalveolar structure cannot be used to accurately identify persons who will experience a large amount of apical root shortening during the course of comprehensive orthodontic treatment with a fixed appliance.