## 4 Discussion
The established correlations between the studied parameters and their changes prove that the action of the RME appliance with dental support affects both the palatal suture, achieves dental-alveolar changes, and remodels the shape and perimeter of the dental arch. With the derived correlations and the following of a strict treatment protocol, it is possible to predict the changes, which will help in the planning of the orthodontic treatment. The expectations for digital planning in orthodontics are to reduce the number of extraction treatments. They have been justified by the expanded possibilities for prognosis and prediction of treatment results. In this regard, any derived linear dependence between the individual characteristics of the dental arch allows for predicting the changes in the applied treatment plan. In borderline orthodontic cases, if the limit of possible changes in the perimeter of the dental arch is known and the clinician is sure that they will achieve the desired results by applying different treatment approaches, he or she will choose non-extraction therapy. Therefore, compared to extraction treatment, conservative treatment with expansion and/or distalization can be planned. This corresponds with the contemporary tendency for more non-extraction treatments. The rapid maxillary expander is a contemporary treatment appliance. Digitally assisted RME techniques are more precise and accurate than traditional. The advantages come from the opportunity that digital appliance planning gives for better visualization and zooming of the working area. The borders of the appliance can be outlined more precisely [14]. The precise positioning of the RME screw in three dimensions--sagittal, transversal, and vertical--allows for the prediction of outcomes and makes the approach more individual for each clinical case. All this makes the appliance more comfortable for the patient and easier for adaptation. The new technologies incorporated into daily practice are well received by the patients. The intraoral scanning is interesting and beneficial for patients with gag reflexes and children. The patients became more motivated and involved in the treatment through good visualization and presentation of treatment objectives. The period of adaptation with the appliance is shortened [45]. The limitation of this study is the small sample size, despite the fact that the observed group is large enough for reliable statistical inferences. Another limitation is imposed by the type of used appliance. The printed RME is for tooth anchorage only and can treat patients with a non-maturated midpalatal suture. This includes criteria that restricted the patient to a matured midpalatal suture [96]. For these patients, an appliance with bone anchorage, such as a miniscrew, is needed. The RME appliance has an undeniable effect on the midpalatal suture and the surrounding structures. The enlarged transversal dimension is achieved through changes in the anatomical structures--maximillary palatine process and palatine bone. These are the structures that form the roof of the oral cavity and the floor of the nasal cavity. Therefore, the expansion achieved with RME influences the nasal cavity and the entire upper jaw by widening the airways. There is a requirement for future investigation on how the transverse expansion influenced the volume of airways. For this purpose, the careful analysis of CBCT images of the airways before and after the treatment with RME, or in particular the digitally assisted RME, would be useful. Such an analysis was made by [PERSON] and co., but with a small sample size [23]. More precise investigations are needed to deepen our knowledge of this connection. Further investigations of how the parameters of the dental arch, such as perimeter, width, and length, are influenced and changed by the action of different types of orthodontic appliances and the derivation of equations and linear or other correlations will deepen and expand the findings of this research.