## 2 Materials and Methods  
This study is a retrospective and cross-sectional study in which the CBCT scans of 169 patients who visited Najran Dental Center for orthodontic treatment were randomly selected. The patients had approached the dental department for orthodontic treatment and were subsequently referred for radiographic imaging of their impacted maxillary canine between 2015-2019. Patients of Saudi Arabian origin and 15-35 years of age were included in the study. Patients with a craniofacial syndromic condition or other systemic bony diseases, supernumerary teeth, odontomas, or odontogenic tumors or cysts associated with an impacted maxillary canine were excluded. Patients in mixed dentition or with an ongoing or previous history of orthodontic treatment were also excluded. The study protocols were approved by the ethical committee at the Faculty of Dentistry, Najran University.  
All the CBCT scans were obtained from the same machine. The exposure parameters were a tube voltage of 120 kVp, a tube current of 15 mA, and a scanning time of 27 s. All patients were scanned in a standing position using a 12-inch diameter field of view (FOV), a 0.376 mm slice thickness, and a total of 512 slices in Digital Imaging in Communications in Medicine (DICOM) format. The scan images were reconstructed in all three sagittal, axial, and coronal planes. The 3D CBCT images were analyzed on a flat-screen monitor by a single orthodontist (A.M.A). The images were adjusted by the investigator for brightness and contrast to optimize the image quality for the best display of root resorption.  
The following observations were made and recorded by a single examiner for each CBCT scan image:  
1. Type of impaction: unilateral or bilateral
2. Side of impaction: left or right
3. Number of teeth resorbed
4. Type of tooth/teeth resorbed
5. Location of resorption in relation to the root level: apical third, apical and middle thirds, middle third, middle and cervical thirds, cervical third, or apical, middle, and cervical thirdsLocation of resorption in relation to the affected surface: mesial, distal, buccal, palatal, mesiopalatal, distopalatal, mesiboucl, distobuccal
* Severity/degree of resorption in the axial plane using [PERSON]'s classification from 2000 [23]: Grade 1: Intact root surfaces except for the loss of cementum
* Grade 2: Slight resorption, up to half of the dentine thickness to the pulp
* Grade 3: Moderate resorption, halfway to the pulp or more; the pulp is covered with dentine
* Grade 4: Severe resorption; the pulp is exposed  
The complete data was entered in Excel software (Microsoft Corp., Redmond, WA, USA) and statistically analyzed using SPSS, Version 20 (IBM Corp., Armonk, NY, USA). An intra-examiner test was performed to assess the reliability of the measurements. Around 20 CBCT scans were randomly selected and re-analyzed after a two-week interval by the same examiner. Intraclass correlation coefficient (ICC) was used to calculate the correlation between two sets of readings. Descriptive analysis was used to obtain the mean and standard deviation of age in the sample. [PERSON]'s chi-square test was used to determine the relationship between gender and the type of impaction (unilateral or bilateral) and side of impaction (left or right). ANOVA statistics were used to identify the relationship between age, location, and severity of resorption. The Kruskal-Wallis test was used to identify the relationship between gender, location, and severity of resorption. The Poisson regression model was used to determine any relationship between age, gender, number of impacted teeth, and number of resorbed teeth. A \(p\)-value of \(<\)0.05 was considered to be statistically significant.