Impacted upper canines: examination and treatment proposal based on 3D versus 2D diagnosis.

Aim: The purpose of this diagnostic cross-over study was to evaluate whether three-dimensional (3D) diagnostics (cone-beam computed tomography, CBCT) was superior to two-dimensional (2D) diagnostics (panoramic X-ray, OPG) in patients with impacted upper canines for assessing their position and the probability of their alignment.

Materials And Methods: Panoramic X-rays, CBCTs, and study casts of 21 patients with a total of 29 impacted maxillary canines were analyzed. Patients with syndromes or tooth aplasias were excluded. A total of 26 dentists of various specialist disciplines rated different parameters, such as canine position and their probability of alignment as well as their relation to and resorption of adjacent teeth. 2D X-rays and study casts were rated first; then 3D images and casts were evaluated at least 2 weeks later. The actual level of displacement was defined by two trained examiners and labeled as the master finding, according to modified criteria established by Ericson and Kurol (1988).

Results: In 64% of all patients, canine position was assessed concordantly in 2D and 3D images. 2D assessments were in slight agreement (κ = 0.374), while 3D ratings were in good agreement with the master findings (κ = 0.714). Two-thirds of the canines' apical regions were judged identifiable in 2D and 3D images; more than 1/4 of the canines' apices were not identifiable in 2D images, but were identifiable in 3D images. The diagnosis of lateral incisor root resorption in the CBCT agreed well with the master finding (κ = 0.634), but examiners overlooked slight resorption in 20% of the patients. In 82% of the patients teeth, treatment suggestions (orthodontic alignment or surgical removal) were the same for 2D and 3D images. Canine inclination visible in the panoramic X-rays was the most important factor influencing the treatment proposal.

Conclusion: Small volume CBCT may be justified as a supplement to a routine panoramic X-ray in the following cases: when canine inclination in the panoramic X-ray exceeds 30°, when root resorption of adjacent teeth is suspected, and/or when the canine apex is not clearly discernible in the panoramic X-ray, implying dilaceration of the canine root. We intend to validate the results of this study in a clinical trial.