The use of panoramic radiographs to localize displaced maxillary canines.

OBJECTIVE: The purpose of this investigation was to develop a reliable method of diagnosing the position of a displaced maxillary canine on the basis of a single panoramic radiograph. STUDY DESIGN: A total of 115 panoramic radiographs depicting 164 displaced maxillary canines were evaluated. The ratio of the width of the displaced canine to the width of the homolateral central incisor (the canine-incisor index) and the ratio of the width of the displaced canine to the width of the contralateral canine (the canine-canine index) were calculated. The height of the crown of each displaced canine was classified in the vertical plane, relative to the adjacent incisor, as apical, middle, or coronal. RESULTS: There was an overlap in the canine-incisor index ranges of the buccal (0.94-1. 45) and palatal (1.15-1.29) canines in the apical zone. In the middle and coronal zones, a clear difference could be seen between the canine-incisor indices of labially (0.78-1.11) and palatally (1.15-1.7) located canines. A cut-off point of 1.15 was determined. CONCLUSIONS: Provided that vertical restriction and the canine-incisor index are used, the panoramic radiograph can serve as a useful indicator for determining the position of an unerupted maxillary canine.