## 4 Discussion  
The present work aimed to investigate the effectiveness of AMCOP(r) elastodontic appliances for the early treatment of patients with a hyperdivergent pattern of growth and a class II malocclusion [24; 34]. Numerous studies have previously evaluated the efficacy of elastodontic appliances in class II malocclusions, reporting improvements in the overjet, overbite, skeletal and dental class II [35; 36; 37; 38; 39]. However, no studies are reported in literature about the use of elastodontic appliances for the correction of hyperdivergent pattern of growth. Although many studies have underlined the dentoalveolar effects of elastodontic devices, significant skeletal changes were also reported [40; 41]. In particular, the elastodontic treatment induces class II correction by improving the mandibular growth and position [39; 42]. A study on the effects of the eruption guidance appliance in the treatment of class II division 1 malocclusions also evaluated the impact of the device on the vertical plane. The study reported that the lower anterior face height increased faster in the experimental than in the control group. This was due to the specific design of the appliance, which had more material anteriorly than posteriorly to promote the eruption of posterior teeth and the depression of incisors. However, the measurements, S-N'Go-Gn and N-S-Gn, did not present statistically significant changes in the study group compared to the control group [43; 44]. Recent work by [PERSON] et al. on the cephalometric effects of AMCOP(r) SC in skeletal class II division 1 cases reported that the elastodontic device does not affect the craniomalibular vertical relationship [35]. In the present study, the cephalometric analysis showed a statistically significant reduction in the ANB angle and overjet, suggesting the efficacy of AMCOP(r) devices on the correction of class II skeletal malocclusions. Furthermore, changes to the vertical plane were also obtained. Significant reductions in the SnaSnp'Go-Gn, S-N'Go-Gn, and Ar-Go-Me were also observed. The occlusal plane, both flat in mild hyperdivergent patients or posteriorly raised in severe hyperdivergent cases, prevents posterior dental eruption and controls vertical development. Skeletal growth is directed more anteriorly and less vertically [20; 45; 46]. The upward and forward mandibular rotation associated with the sagittal mandibular repositioning improves the sagittal discrepancy and, at the same time, reduces lower facial height [47; 48]. Furthermore, these devices can correct functional problems of the soft tissues, such as a lingual malposition, a centripetal thrust of the lips and cheeks, and oral breathing [49; 50]. They improve skeletal and dentoalveolar malocclusions and restore normal muscular activities, rebalancing the period, oral, and lingual musculature [27; 51; 52; 53; 54; 55; 56]. A study that found a link between muscle strength and occlusal barycenter confirmed the idea that inadequate musculature contributes to hyperdivergent growth. As a result, strengthening the muscle may change the occlusal barycenter. The AMCOP(r) devices perform this function  
Figure 7: **(A,B)–**Patient (D.L.) hetero-lateral teleradiography X-ray: before treatment T0 (A) and after treatment T1 (B). by causing constant stimulation of the masticatory muscles [57]. The devices can improve neurovegetative oropharyngeal functions, sucking and swallowing, chewing, phonation and breathing, and restoring the correct nose-mouth laryngopharyngeal function [58]. The subjects with a class II malocclusion and a hyperdivergent growth pattern have a narrower anteroposterior dimension of the upper pharyngeal airway due to mandibular retrusion and vertical maxillary excess. Other factors may also be favorable, such as the obtuse soft palate and the lower position of the hyoid bone. A narrow pharyngeal airway space could predispose to mouth breathing and obstructive sleep apnea; thus, early treatment is essential [12; 59; 60; 61; 62].