## 2 Materials and Methods  
This case-controlled clinical study included 75 participants (43 girls, 32 boys). The participants were divided into two groups: the experimental group (with impacted canines) and the control group. The experimental group included 32 patients who were referred to the Orthos Institute for orthodontic treatment and had at least one impacted canine in their maxilla. Before inclusion into the study, and after receiving oral and written information about the clinical trial, the patients and their parents or guardians signed the informed consent form (Institutional Review Board Statement). Thirty-two patients with at least one impacted canine without hereditary syndromes or orofacial clefts were included in the study. Forty-three patients were included in the control group. The participants in the control group were selected according to the experimental group based on the participant's gender, age, and skeletal maturity. The patients in the control group had no major orthodontic malocclusion, and their index of malocclusion was categorized as none or mild (EF values < 16 points) according to the EF index [21]. The patients underwent a detailed clinical examination, and intraoral and extraoral photographs were taken. The upper and lower dental arches were scanned with an intraoral scanner, and the bites were registered. Three-dimensional models were created with a 3 Shape Trios 3 intraoral scanner (3 Shape, Copenhagen, Denmark). Lateral cephalograms of the head and neck were used to assess skeletal maturity using the CVS method. Skeletal maturity was assessed based on the morphology of the second-to-fourth cervical vertebrae [22; 23; 24]. Intraoral photographs and models were used to determine the presence of a deep bite, hypoplastic lateral incisors, rotation of neighbouring teeth, or infraocclusion of the deciduous molars. A deep bite was defined as an overbite of more than 4.1 mm, measured either during the examination with calipers or on an intraoral 3D model [25,26]. The presence of hypoplastic lateral incisors, rotation of neighbouring teeth, and deciduous teeth in the infraocclusion due to ankylosis was determined by analyzing the intraoral 3D model. In the group of impacted canines, each impacted canine had its position (palatal or buccal), the presence of a deciduous tooth, and the angle of the impacted canine noted. The position and presence of impacted canines were assessed on digital panoramic radiographs. The angle of the impacted canine axis (\(\alpha\)) was measured digitally between the vertical median line and the canine axis line (Figure 1). The measurements were performed by the same person twice, 1 week apart. The mean values of the two measurements were considered as the final measured values. Based on the analysis of 3D study models of the maxilla, the surface area, the projection area, and the volume of the maxilla were determined. To determine the surface area and volume of the maxilla, we imported the 3D study models in digital form into a customized program for analyzing the morphological features of the jaws based on Rapid Form(tm) 2006 software (Inus Technology Inc., Seoul, Republic of Korea). The software, which uses a high-quality polygonal mesh, enables precise visualization and calculation of the selected surface and volume of the jaw. The program was developed in collaboration between the University of Ljubljana and Cardiff University and adapted for the analysis of morphological features, and described in an article by [PERSON] et al. [27]. The method has been used in several studies so far and is considered an established method for the assessment of morphological features. It has already been described in detail [28, 29, 30, 31]. Three-dimensional models of the maxilla made it possible to measure morphological features by measuring the projection of the surface of the palatal vault and the volume of the palate.