Maxillary impacted canines (MIC), which have a significant place in orthodontics and can be easily noticed clinically, have frequently been a topic of research in the literature along with the dentoalveolar and maxillofacial structures that are related to . There are studies stating that there is a relationship between transverse width and impaction, as well as others reporting no such relationship [5, 8].
In our study, patients with palatal impacted canines had lower nasal cavity widths. Also, there was no significant difference between the nostril widths of the groups. Kim et al.  reported similar nasal cavity and nostril widths to those in groups with labial and palatal impaction, and they found no significant difference between their groups. In another study  as opposed to our result, there was no significant difference between nasal cavity widths of the individuals with palatal MIC and those with erupted canines. Some studies reported a close relationship between nasal cavity width and maxillary alveolar width . Likewise, in a study using a unilateral MIC split-mouth design  the nasal cavity was wider on erupted side than the impacted side, but the difference was not statistically significant. Considering that the canine tooth germ development location, a narrow nasal cavity may lead to canine teeth developing in a more mesial position, or maybe palatal position affects the width of the nasal cavity.
In the control group in our study, molar palatal depth was significantly higher than impacted groups and the premolar palatal depth was significantly lower in palatal group than other groups. In another CBCT study , there were significant differences in these measurements between erupted and impacted groups, and these values were found to be distributed as control > unilateral > bilateral in descending order. In addition to this, other studies have reported that the palatal depth of individuals with impacted canines, whether buccal or palatal, is similar to that in individuals with erupted teeth [13, 14]. Kim et al.  determined significantly lower molar palatal depth values in their palatal impaction group, where the palate was narrower and deeper. Differently from the germ of other teeth, the maxillary canine germ develops on a much higher level .
In our study, the individuals in the control group who had erupted canines had higher MAPD, BMW(6), AMW(6), APMW(4) values than the individuals with labially and palatally impacted canines. As an important finding, all measurements associated with the molars showed significant differences between the control group and the groups with impaction. Verma and Dinesh  determined 1st molar basal alveolar and arch widths of adults with bilateral or unilateral MIC to be significantly higher than erupted group. While the 1st premolar basal alveolar width was significantly higher in control group, bilateral group had the lowest mean values in terms of 1st premolar arch width and 1st molar basal alveolar width values. While another study included CBCT images of young adults  did not show a significant difference among the control, unilateral and bilateral impaction groups in terms of their 1st premolar, 2nd premolar and 1st molar arch widths, the unilateral group had the lowest values in all these measurements. In a similar study , BMW, MAW and PMAW values were significantly higher in control group than in other groups like in our study, but there was no significant difference between the groups in terms of their PMBW values. In the groups for which they compared different combinations of unilateral/bilateral and palatal/buccal impactions, they found no significant difference in terms of molar or premolar basal or alveolar widths. According to Schindel et al.  while maxillary transverse deficiency is associated with unilateral impaction in patients in mixed dentition period, it is not associated with bilateral impaction.
As there are various etiological reasons related to impaction, the position of the impacted tooth is the most important variable that needs to be considered. In a study conducted with CBCT images of individuals over the age of 12 , BMW, AMW and APMW values were found significantly lower in both buccal and palatal impaction groups than erupted group, whereas impaction groups did not significantly differ. Similarly, some studies have reported no significant relationship between palatal impaction and premolar or molar dental or alveolar width values in CBCT examinations [17–19]. Buccal impaction, on the other hand, is frequently associated with a narrow maxilla . According to Richardson , palatal impaction is a consequence of the failure of maxillary canine that is continuing to erupt to move from the palatal side to the buccal side. However, it was also reported that approximately 80% of individuals with palatally impacted teeth have a sufficient arch perimeter .
There are studies with similar methodologies to the one in our study, but these studies have used dental casts. One of these studies revealed higher levels of maxillary transverse discrepancies in individuals with MIC in a sample of patients at the ages of 10 to 25. In addition to this, interpremolar and intermolar dental arch widths of the labial MIC group were significantly lower than those in palatal MIC and erupted control groups . Ghaffar et al.  could not find a statistically significant relationship between maxillary transverse dimensions and potential impaction in individuals in the mixed dentition period. Langberg and Peck  could not identify a difference in dental arch widths between palatal impaction and erupted canine groups. As a result, they emphasized that genetic factors may be more effective on palatal impaction than maxillary transverse deficiency.
In our study, all measurements were higher in male patients in comparison to the females, and this difference was significant only in molar alveolar widths and premolar basal maxillary widths. According to the assessments of the positions of impaction, the anatomical structures of female patients were affected by the position of impaction to a higher extent in comparison to the males. In both sexes, while there was no significant difference between three groups in terms of their nostril widths, the molar and premolar alveolar widths were higher in the control group, and the molar basal width in the palatal group was significantly lower than that in the control group. A difference was observed in the premolar palatal depths among the female patients between the labial and palatal groups, while the male patients in these two groups had different nasal cavity widths. For both sexes, regardless of the position of the impacted teeth, the only parameter differing from the control group was the alveolar width.
Refaat and El-Desouky  reported that female patients with palatal MIC had a deeper palatal structure than those with buccal MIC. According to the researchers, the strength of the relationship between impacted canine position and palatal depth was much higher in the female patients than the male patients. Moreover, they reported that in the male patients, the intermolar width and arch length values were higher than those in the female patients in the palatal impaction and erupted groups, and the palatal depth, maxillary width and nasal cavity width values were higher than those in the female patients in the buccal impaction group. Verma and Dinesh  reported that female molar and premolar basal alveolar widths were lower than male ones, and this may be an etiological factor of impaction. Ruiz-Mora et al.  examined post-traction buccal and palatal impacted canines and revealed that the degree of changes in the palatal, buccal and distal maxillary alveolar bone measurements was higher in female patients in comparison to male patients. In another study conducted for investigating CBCT images in adult MIC cases , sex was identified as the only variable that affected all transverse measurements, and the transverse measurement values of female patients were lower than those of male patients. Many studies carried out about dental casts [22, 26] have shown higher measurements in male patients than female patients in MIC cases, especially for measurements made in the anterior region. It may be considered that this situation indicates a higher basal alveolar width value in males, and therefore, a lower probability of impaction . In their split-mouth study involving CBCT analyses, Tadinada et al.  did not find a difference between sexes in terms of the arch perimeter, buccopalatal width or alveolar height measurements in unilateral palatal impaction cases.