## 1 Introduction  
Maxillary transverse deficiency is characterized by an upper arch with reduced transverse dimensions, which can be clinically identified by an oval or deep palate, V-shaped arch, and wide buccal corridor. Its etiology is mainly related to environmental factors, predominantly mouth breathing and persistent oral habits [1]. Rapid maxillary expansion (RME) is the conventional method for transverse maxillary deficiency treatment; it can effectively enlarge the maxilla by applying a rapid transverse force of high magnitude to the upper teeth resulting in the opening of the midpalatal suture [2]. The midpalatal suture (MPS) is a single suture that matures and structurally changes under the influence of mastication, hormones, genetics, and mechanical factors. The closure of the suture does not necessarily imply the end of skeletal body maturation. In addition, there is a high amount of individual and morphological variation [3, 4]. However, in late adolescence and in adults, there is limited skeletal expansion due to the interdigitation of the MPS that occurs with increasing age [3]. Skeletal maturation during adolescence and young adulthood leads to the gradual closure of the palatine suture, starting from the back and moving forward. As a result, the skeletal response to RME decreases. In these cases, conventional RME can produce side effects, such as the failure to separate the maxilla, labial tipping of the crown, root resorption, and marginal bone resorption [5]. The most common treatment for these cases is surgically assisted rapid maxillary expansion (SARPE) [6]. It is an invasive procedure with high financial costs and requires hospitalization and general anesthesia. In this context, MARPE emerges as a less invasive and efficient option in patients without growing potential. Thus, a personalized assessment of the patient's skeletal maturation stage in the area of interest could be an important predictor of RME success [7]. To assist in the clinical decision to treat a patient using conventional RME or SARPE, indicators of MPS maturation have been proposed, which include the following: suture morphology on occlusal radiography [8], skeletal maturation indicator on hand and wrist radiography [9], indicators of cervical vertebrae maturation (CVM) in teleradiography [10], and a classification of five stages of maturation of the median palatine suture proposed by [PERSON] et al. [11]. [PERSON] et al. proposed a new method for evaluating the maturation of the palatine suture by determining the bone density of this region, using cone-beam computed tomography, which demonstrated a significant correlation with the amount of skeletal response to RME treatment assessed in their study [7]. An important clinical decision is the retention period after RME; the literature reports a variation from 2 to 12 months. In general, a period of 3 months is used [12]. Although it is a plausible period for RME, this time may not be enough for SARPE. Studies state that a retention period of 6 months after RME allows for suture reorganization with a similar density to that before expansion [13; 14]. However, 7 months after SARPE, the density values showed that the remineralization was still incomplete, and it was questionable if the ossification present up to that time would be able to resist the forces exerted by adjacent bone structures and if recurrence could be avoided [15; 16]. In recent years, clinical practice has benefited from computed tomography (CT) as it has diagnostic advantages over traditional two-dimensional images [17]. CT allows for more accurate assessments and diagnoses, is an efficient, non-invasive, and fast method, and allows for reliable linear and angular measurements [18]. Using CT, it is possible to visualize the palatine suture without any overlapping of anatomical structures [19].