Three-dimensional reconstructions of CT scans and cone beam CT of impacted maxillary canines in order to locate areas of ankylosis before orthodontic traction

Purpose: The aim of this study was to model impacted maxillary canines and determine whether areas of ankylosis were present before undertaking orthodontic traction.

Material and methods: Amira/ResolveRT™ software, version 5.0, by FEI Company is a meshing and surface-rendering program that was used to produce three-dimensional reconstructions from CT scans and cone beam images of the impacted canines of 30 patients (10 cone beam files and 20 CT scan files).

Results and discussion: The presence of zones of ankylosis on the roots of certain impacted canines is revealed by the inversion of the direction of meshing on the tooth surface and on a larger scale by invagination of bone tissue into the tooth tissue at various densities measured in Hounsfield units by the AMIRA™ software program. This observation can guide treatment towards extraction of the impacted tooth, its autotransplantation, or deep alveolar corticotomy, followed by mobilization when the canine is in a vestibular position.

Conclusion: AMIRA™ software made it possible to detect zones of ankylosis on the roots of certain impacted canines and to adopt a treatment program different from conventional surgico-orthodontic traction. The final aim is to reposition the impacted canine without endangering the adjacent teeth.