## 4 Discussion
's study [12] were selected by matching the stage of skeletal maturity without considering the chronologic age of the patients, the airway volume augmentation observed in the treated group could be associated mainly with adenoids and Waldeyer lymphatic ring regression occurring from the age of 11 years, rather than an airway development. On the contrary, in our study, the modification of airway dimensions following MARA treatment was not registered in the results, as the mean ages of the patients in the treated and control groups are higher than in the study by [PERSON] et al. [12]. [PERSON] et al. 's conclusions [20] were additionally confirmed by the study of [PERSON] et al. [21], which emphasized the fact that the nasopharyngeal dimension increases simultaneously and linearly with the adenoids until the age of 10 years, reaching a peak between 10 and 11 years. From that point, the adenoids and palatine tonsils regress rapidly, reaching a growth plateau at 11 years. After this age, their size shows a slight reduction, and then it stabilizes. In addition to these considerations, as reported by [PERSON] et al. [22], airway changes in relation to skeletal modifications. In relation to this, [PERSON] et al. [23] by MRI analysis concluded that the middle and lower thirds of the face continue to grow linearly along the sagittal and axial planes during infancy and, simultaneously, the soft tissues that delineate the upper airways, including adenoids and tonsils, evolve in constant proportion to bone structures in order to maintain airway patency. In addition, the literature has demonstrated that fixed functional appliances can stimulate mandibular growth in Class II patients with mandibular retrusion if the device is applied at the ideal timing [24]. In relation to this, [PERSON] et al. [25] showed that pubertal growth spurt represents the most favorable timing for treatment with MARA in order to achieve a greater amount of mandibular skeletal effects, such as a statistically significant augmentation of total mandibular length (2.6 mm), and a minimal amount of dental compensation at the lower arch level. In our study, as reported in Table 3, not all patients were treated with MARA at the pubertal growth spurt (12.5%), whereas, based on the individual skeletal maturity, most subjects were pre-pubertalal (25%) or post-pubertalal (66.7%) at T1. In the present study, MARA did not induce statistically significant skeletal changes in mandibular growth or in mandibular sagittal position. Based on these findings, the lack of changes in upper airway dimensions may be related to the absence of skeletal changes at the mandibular level since both develop consistently and simultaneously. In disagreement with what was observed in [PERSON] et al. 's study [12], [PERSON] et al. [26] evaluated changes in airway dimensions on lateral cephalospor in 10 patients treated with mandibular activators, such as the Andresen monoblock and the Twin Block, according to [PERSON], compared to a control group of 10 untreated subjects. In line with the results of our study, [PERSON] et al. [26] found no significant differences in upper, middle, and lower airway changes between the two groups during the observation period (superior-posterior airway space (SPAS) 1.3 mm vs. \(-\)0.5 mm, \(p\) = 0.1157; middle airway space (MAS) 1 mm vs. 0.2 mm, \(p\) = 0.2954; inferior airway space (IAS) 1.1 mm vs. \(-\)0.3 mm, \(p\) = 0.4682). Our study not only focused on the analysis of airway dimensions but also evaluated the skeletal and dentoalveolar effects induced by MARA. On skeletal level, the results of the present study showed that Wits and ANB angle were significantly reduced in the treated group, demonstrating the achievement of a better relationship between the mandible and the maxilla (Wits \(-\)1.0 mm and ANB \(-\)0.7\({}^{\circ}\), \(p\) = 0.009 and \(p\) = 0.038). These results are in line with the study of [PERSON] et al. [18], and they are also supported by the study by [PERSON] et al.