Assessment of the root apex position of impacted maxillary canines on panoramic films.

Introduction: In this study, we aimed to analyze the root apex positions of impacted maxillary canines on panoramic radiographs according to their labiopalatal positions and to propose a new panoramic radiographic predictor of impacted maxillary canines.

Methods: Paired panoramic films and cone-beam computed tomography images of 104 patients with unilateral impacted maxillary canines were selected. The sector locations of the impacted canine root apices on the panoramic radiographs were compared with the labiopalatal positions of impacted maxillary canines on cone-beam computed tomography. Statistical correlations between panoramic and cone-beam computed tomography findings were examined with the chi-square test.

Results: A statistically significant association was observed between the sector locations of impacted canine root apices and the labiopalatal positions of the canines (P <0.001). The root apices of labially impacted canines were more frequently located in sector 2 (corresponding to the lateral incisor position), those of palatally impacted canines were more frequently located in sector 4 (corresponding to the first premolar), and those of midalveolus impacted canines were more frequently located in sector 3 (corresponding to the canine).

Conclusions: On panoramic films, the root apices of palatally impacted canines tended toward the root apices of the maxillary first premolars, whereas those of labially impacted canines tended toward the root apices of the maxillary lateral incisors. Therefore, the sector locations of impacted canine root apices on panoramic radiographs could be used for the early prediction of maxillary canine impactions and determination of the labiopalatal positions of impacted canines.