# Effect of the Mandibular Repositioning Appliance (MARA) on Posterior Airway Space (PAS)
###### Abstract  
Aim of the study was to show the effect of skeletal Class II treatment with the mandibular anterior repositioning appliance (MARA) on the sagittal posterior airway space (PAS) diameter. A total of 53 patients were selected retrospectively: 26 male patients (median 13 years, age span 10-19 years) and 27 female patients (median 14 years, age span 11-47 years). All patients had lateral cephalograms taken at T1 (before MARA treatment) and at T2 (after MARA treatment). Average treatment took 13.1 \(\pm\) 7.5 months (Group 1) and 10.5 \(\pm\) 4.5 months (Group 2), respectively. The following PAS parameters were obtained at T1 and T2: TI (Tangent Point 1), Me/Gn (menton/gnathion), DW (dorsal wall). Additionally, Bjork's sum angle, SNA, SNB and ANB were determined. The male patients showed a higher increase in the anteroposterior diameter of the PAS (+27.5%) compared to female patients (+11.6%). Male participants had a significantly higher PAS (\(p\) = 0.006) than female participants (\(p\) = 0.09). Although not significantly, Bjork's sum angle decreased in both groups. In general, compared to female patients, male patients showed a greater decrease between T1 and T2. SNA and SNB exhibited varied behavior between T1 and T2, with some individuals reporting a decrease and others reporting an increase. SNA tended to decrease in general. In terms of ANB, the male participants displayed a decrease from T1 to T2. Treatment of a skeletal Class II malocclusion with the mandibular anterior repositioning appliance (MARA) caused an increase in the sagittal posterior airway space (PAS) diameter and, thereby, might be effective against obstructive sleep apnea. m +
Footnote †: journal: Medical  
an obstructive sleep apnea syndrome (OSAS) [4]. OSAS is a risk factor for cardio-circulatory diseases, stress-related diseases and diabetes mellitus [5; 6]. Newer research also suggests an increased risk for chronic inflammatory diseases (immuno-suppressive effects) and dementia, the latter of which seems to be related to a loss of function of the so-called glymphatic system [7; 8; 9; 10; 11]. A possible common denominator for all of these damaging effects is repeated nocturnal catecholamine- and cortisol-mediated emergency responses triggered by a drop in O\({}_{2}\) saturation [12; 13]. In view of the potentially fatal outcome, especially in adults, OSAS is a condition in urgent need of adequate treatment [12]. Treatment with mandibular advancement devices (MADs), together with CPAP ventilation and orthognathic surgery, is the standard so far in OSAS cases [14]. Orthognathic surgery remains the only permanently curative option; however, it is highly invasive. ventilation via CPAP (continuous positive airway pressure) or variants thereof are often poorly tolerated by some OSAS patients [15]. The search for a viable middle ground between those two has so far yielded MADs therapy. It has been established that the lateral cephalogram is a useful technique for confirming the possible significance of OSA in patients experiencing suspected symptoms [16]. They are part of the standard orthodontic diagnostic regime. The mandibular anterior repositioning appliance (MARA) is a fixed functional appliance for Class II correction [17]. In this context, the MARA can be viewed as being analogous to MADs therapy. The MARA, however, produces permanent dentoalveolar and skeletal effects, as opposed to MAD treatment. It could be hypothesized that--considering its effect--the MARA be situated somewhere between MADs and maxillofacial surgery. The MARA is significantly more invasive than MADs, which is only worn at night, whilst simultaneously avoiding the potential risks and complications associated with maxillofacial surgery. There are multiple studies on changes in the PAS lumen after orthognathic surgery, but there is also a growing number of studies focusing on fixed functional appliances. However, such studies are still outnumbered by the former [18; 19].