Predicting and preventing root resorption: Part I. Diagnostic factors.

The purpose of this study was to determine whether it would be possible to identify pretreatment factors that will allow the clinician to predict the incidence, location, and severity of root resorption before the commencement of orthodontic treatment. The records of 868 patients who were treated with full, fixed edgewise appliances were obtained from 6 private offices; full-mouth periapical radiographs were used to accurately assess apical root resorption from first molar to first molar in both arches. The results showed that resorption occurs primarily in the maxillary anterior teeth, averaging over 1.4 mm. The worst resorption was seen in maxillary lateral incisors and in teeth with abnormal root shape (pipette, pointed, or dilacerated). Adult patients experienced more resorption than children did in the mandibular anterior segment only. Asian patients were found to experience significantly less root resorption than white or Hispanic patients. Increased overjet, but not overbite, was significantly associated with greater root resorption. There was no difference in either the incidence or severity of root resorption between male and female patients.