Canine retraction with elastomeric chains connected from the miniscrews to the power arms. 
incisive foramen
A pre-retraction cone beam computed tomography (CBCT; Aceton X-mind Trium. La Cietat. France) was acquired within two weeks of the premolar extraction. A second CBCT was acquired after 6 months of canine retraction. Patients who missed the follow-up CBCT were rescheduled within 7 days. The DICOM images were imported into InVivo 5 software (version 5.3.1; Santa Clara, CA, USA).Using a force gauge (50-500 g, Dental Morelli Ltda, Sorocaba, São Paulo, Brazil), the elastomeric chains (Short, Silver, American Orthodontics, Sheboygan, Wis.) were stretched between the TADs and the power arms, to deliver 150g. According to the allocated intervention, the elastomeric chains were replaced every two, four, six or eight weeks. It was possible for a single patient to have a different reactivation schedule for each quadrant. The TADs stability was checked at each visit.Using the Invivo 5 software, CBCT landmarks were identified on the 3D volume and adjusted on the multiplanar slice locator, in the axial, sagittal and coronal views, using the Invivo 5 software. The stable bony landmarks; incisive foramen, the anterior and posterior nasal spines and the right and left mental foramina were identified (
