In the January 2013 issue, Dr Davide Mirabella et al reported the successful treatment of impacted canines by extracting them, substituting first premolars, and then achieving a good occlusion and facial profile (Mirabella D, Giunta G, Lombardo L. Substitution of impacted canines by maxillary first premolars: a valid alternative to traditional orthodontic treatment. Am J Orthod Dentofacial Orthop 2013;143:125-33).

This approach simplified the conventional orthodontic-surgical therapy and avoided many unpredictable risks during orthodontic extrusion of impacted maxillary canines, including inadequate alveolar bone and gingiva of the impacted teeth, and root resorption of adjacent teeth.

This replacement approach seems to be especially suitable for horizontally impacted canines, since those are the most difficult to treat. So far, a conventional 2-dimensional panoramic radiograph is still considered the primary diagnostic basis for the location of impacted canines. However, with the emergence and development of 3-dimensional cone-beam computed tomography, the diagnostic inaccuracy for the localization of impacted canines from a panoramic radiograph is evident and could result from distortions or projection errors of complex 3-dimensional structures projected to a 2-dimensional plane, thus increasing the risk of misinterpretation.

Alqerban et al reported a highly significant difference between the panoramic radiograph and the cone-beam computed tomography image in impacted canine angulation. Recently, I found that our 3 patients showed high horizontal impaction on the panoramic radiographs, whereas, in fact, they were all obliquely impacted. Two of the 3 patients had mesial to distal oblique impactions, and the other had buccal to lingual oblique. Such a big diagnostic difference might result in a completely different treatment method. Inaccurate 3-dimensional diagnosis of the location and orientation of impacted teeth might be an important reason for failure in the treatment of impacted canines.

We have 2 questions. First, in Figure 3 of the case report, the right canine was high and horizontally impacted, but in Figure 4, it appeared to be labial and oblique. Could the tooth have been obliquely impacted?

Our second question deals with occlusion. How did you adjust the occlusion for the first premolars to function as canines? Did you use a canine bracket on the first premolar? Did you change the torque of first premolar?