# Cephalometrics in Obstructive Sleep Apnea Patients with Mixed Dentition
## 2 Materials and Methods  
The study was conducted in the period from 2017 to 2022 at \"Somnus\" Neurology Clinic and University Dental Polyclinic N1 of Yerevan State Medical University after Mkhitar Heratsi (YSMU). The cohort study included 39 children (71.8% boys and 28.2% girls, mean age 9.45 years, standard deviation 1.86, range 7-13 years) with sleep-related breathing disorder symptoms. The research was conducted by the Helsinki Declaration and ethical clearance has been guaranteed from the Ethical committee of the YSMU (N. 10-15; 19 June 2014). Participation in this study was voluntary and participants signed an informed consent. The STROBE guides were followed during preparation of this article. _Inclusion criteria_  
* Nasal breathing disturbance
* Denofacial anomalies (malocclusion)  
_Exclusion criteria_
* Bad habits (tongue, lip, finger sucking, subject sucking)
* Refusal of the examination (conducting a cephalometric or polysommographic/polygraphic study),
* Patients undergoing orthodontic treatment at the time of recruitment  
_Orthodontic examination_ consisted of a preliminary assessment of the maxillofacial features onsite and referral for cephalometric X-ray examination using a Planmeca ProMax Type 3D+ (Planmeca OY, Helsinki, Finland) adjusted to 12 mA, 90 kV and a time exposure of 0.30 ms and analysis of the results using Romeras Viewer 5.4.1. software (Planmeca OY, Helsinki, Finland). All children were oriented in a natural head position (NHP). Cephalometric analysis was performed manually twice by different others to exclude the factors of human mistakes, and included linear and angular parameters. For the sagittal analysis, SNA\({}^{\circ}\), SNB\({}^{\circ}\), and ANB\({}^{\circ}\) angles were used to determine the maxilla and mandible positions relative to the anterior part of the cranial base and the corresponding skeletal class. For the vertical analysis, we determined the ArGoGn\({}^{\circ}\) and Ba-S-PNS\({}^{\circ}\) angles. The position of the hyoid bone was assessed using AH-C3 (mm). It shows the horizontal distance from AH to C3, where AH is the most anterior and superior point on the body of the hyoid bone and represents the underside of the tongue, and C3 is the third cervical vertebra. EbTt is the distance from the tip of the epiglottis to the tip of the tongue. SNP-Eb is the distance between the posterior nasal spine and the tip of the epiglottis. The MnPI value is the lower jaw length in mm. The MxPI value is the upper jaw length in mm. The size of the soft tissues and oropharynx was measured by PAS1, PAS2 (pharyngeal width measured between the posterior pharyngeal wall at its narrowest point and the most anterior airway point on the soft palate), PAS3, and PAS min (lower airway space between the posterior inferior pharyngeal wall and the most anterior airway point on the tongue) [31; 32; 33]. Patients were then referred to the sleep disorders center for a diagnostic study of sleep using portable respiratory polygraphy (Embletta X10) or night polysomnography (Embla N7000). Sleep parameters were calculated using Sommologica 5.1.1. software. Immediately before the PSG examination, a comprehensive physical examination was performed, which included anthropometric measurements such as height and weight to calculate body mass index. SB was assessed by bilateral masseter electromyography (EMG), and the audio and video evaluation bruxism episodes were scored according to the standards of the AASM in three forms: phasic, tonic, and mixed. For the consideration of SB, EMG bursts should not be separated by >3 s to be considered part of the same episode, and EMG activity has to be at least twice the amplitude of the background EMG [15]. The apnea-hypopnea index (AHI), oxygen desaturation index (ODI), average saturation, obstructive sleep apnea index (OSAI), AHI in the supine and non-supine positions, central sleep apnea index (CSAI), nonrapid eye movement sleep (NREM) AHI, rapid eye movement sleep (REM) AHI were all measured and recorded.