## 4 Discussion
In our experimental group, hypoplastic lateral incisors were present in 48.3% of participants, which is a slightly higher prevalence compared to other studies in which hypoplastic lateral incisors were found in 17-18% of participants with impacted maxillary canines [34,38]. We found that the odds of impaction were 3.5 times higher when the tooth adjacent to the impacted canine was rotated. The lateral incisor and the first premolar erupt close to the canine. On average, the lateral incisor erupts 3 years and the first premolar 1 year before the canine. If neighbouring teeth erupt in an improper position of the root, their root tips may tip into the eruption path of the canine and block its normal eruption [8,39]. Conversely, an impacted canine can exert pressure on the roots of neighbouring teeth and cause spontaneous orthodontic tooth movement, which manifests as tipping and/or rotation. Some authors investigated whether the ankylosis of the deciduous tooth that leads to infraocclusion is related to the impaction of the maxillary canine [15,38]. In the present study, the comparison between the groups did not confirm this hypothesis. It is important to mention that the number of participants with ankylotic deciduous teeth was very low (1 or 2), which is reflected in the very low power of the statistical test. When comparing the maxillae based on the 3D morphological features, we found that the palate of the group with impacted canines was significantly smaller. The volume of the palate, the surface area of the palate, and the projection area of the anterior palate (4-4) were significantly smaller in the experimental group. The projection area of the entire palate (6-6) showed a similar pattern but did not reach the level of statistical significance (\(p=0.136\)). The different results between the palatal surface and projection surface parameters indicate a possible role of the vertical dimension of the maxilla in the impaction of the upper canines, as the projection surface (in contrast to the palatal surface) is only influenced by the transversal width and sagittal height. Several authors have emphasized the possible role of the vertical dimension in the impaction of maxillary canines [40,41]. In contrast to our study, previous studies have used linear measurements instead of using 3D measures such as surface area and volume. The advantage of this 3D measurement technique is that it reduces the likelihood of measurement errors due to local model peculiarities or defects on a 3D model. We tested a possible interaction between the morphological characteristics of the maxilla and the intraoral conditions. The tests revealed no significant interaction between a deep bite, hypoplastic lateral incisor, or rotation of the neighbouring teeth with the 3D morphology of the maxilla. We can conclude that the 3D morphological features of the maxilla are an independent sign associated with the maxillary maxillary canines. [PERSON] et al. analyzed 3D models and found that the maxillae of participants with impacted canines were significantly narrower in the transverse dimension and shorter in the sagittal direction, while the vertical height of the palate was not significantly different [40]. However, [PERSON] et al. measured the vertical height of the palate on CBCT images and concluded that both the anterior and posterior heights of the palate were smaller in the groups with impacted canines [41]. A recent systematic review measuring CBCT images confirmed that the width of the impacted side was narrower, and palatal volume was smaller when impacted canines were present [42]. These findings are consistent with the results of our study. According to [PERSON], a narrow apical base of the maxilla and a lack of space in the maxilla may be the cause of canine displacement, which may lead to impaction [43]. The results of our study show that in the presence of a persistent primary canine, the odds of impacted permanent canines are higher. This is consistent with a study by [PERSON] et al.