Abstract: PURPOSE: To evaluate the influence of pretreatment radiographic features (angle, distance, and location) on the duration of active orthodontic traction. METHODS: Sixty maxillary unilateral impacted canines were selected to analyze the panoramic features(angle, line spacing, and location) in pre-treatment patients， the results were evaluated using SPSS19.0 software package for multivariate regression analysis. RESULTS: Pretreatment radiographic variables (angle, line spacing, and location) were significantly associated with the duration of orthodontic traction. The sex and site of impaction did not significantly affect the duration of traction. CONCLUSIONS: Impacted canine angle, distance and position can predict the orthodontic traction time.

Key words: Impacted canine, Panoramic radiographs, Orthodontic traction