## 2 Materials and Methods
### Radiographic Outcomes  
All radiographic evaluations, including CBCT and orthopantomography (OPG) analyses, as well as measurements, were conducted by the same investigator.  
All images were acquired with patients in a standing position using a consistent machine (Planmeca ProMax 3D CBCT; Planmeca OY, AsentaJankatu 6, Helsinki, Finland). Subsequently, DICOM (\"Digital Imaging and Communication in Medicine\") records were transferred into the HorosTM platform (Horos Project, Annapolis, MD, USA) to orient the images.  
Within the CBCT, the subsequent factors associated with the morphology of the impacted canines and ipsilateral lateral incisors were recorded:  
* Mesiodistal diameter on the coronal section of the canine crown (MD3) (Figure 1).  
* Mesiodistal crown diameter of the lateral incisor (MD2) (Figure 4).
* The width across the maxillary arch was measured as follows:
* Transverse distance between the palatal cusps of upper first premolars (1.4 and 2.4 teeth) (Transv4).
* Transverse distance between mesiopalatine cusps of upper first molars (1.6 and 2.6 teeth) (Transv6) (Figure 4).  
External root resorption of the upper lateral incisor was evaluated on sagittal and axial CBCT slices, defined as clear substance loss on the root surface. It was recorded as a dichotomous outcome, noted as 'Yes' (1) or 'No' (0).  
The primary dependent variables included angular and linear measures of the canine position, which were as follows:  
* The angle formed between the canine's longitudinal axis and the occlusal plane passing through the cusps of the first molar and premolars (Ang3 Poe).
* Angle connecting the canine's longitudinal axis and the midline, observed in the frontal plane (Ang3 LMf).
* Angle among the longitudinal alignment of the canine and the palatal suture, noted in the transverse plane (Ang3 LMt).
* Linear measurement of the distance between the canine cusp and the occlusal plane (in millimeters) along the sagittal plane (DCPo) (Figure 5).  
Figure 4: Transverse diameter: (**a**) MD2: meso-distal coronal diameter of the lateral incisor. (**b**) Transv4: maxillary width of the palatal cusp of the right first premolar to the left first premolar. (**c**) Transv6: maxillary width of mesiopalatine cusp from right first molar to left first molar.  
Figure 3: Lateral incisor measurements: (**a**) Orientation of the longitudinal axis. (**b**) LongRad2: root length of lateral incisor. (**c**) OG2: occluso-gingival length of lateral incisor and BL2: lateral incisor coronal bucco-lingual diameter.  
On the OPGs obtained from CBCTs, the following measures were taken:
* Mesiodistal position of the cusp tip of the canine according to [PERSON] and [PERSON] [34; 35]. The described five sectors are defined by the longitudinal axes of the permanent central and lateral incisors and parallel lines passing through the contact points between the central incisors, the lateral and central incisors, and the mesial and distal surfaces of the deciduous canines. Sector 1 represents the most distal position, while Sector 5 corresponds to the most mesial location [36].
* Angulation of the long axis of the upper canine relative to the central line (Ang3 LMfP).