This prospective, controlled study will compare the 3D cephalometric analysis of bone and craniofacial soft tissues in young (18-35 years) non-overweight apneic adults phenotype between a test group (with AHI 15) and a control group (healthy subjects with AHI < 15).

Objectives The goal of this study is to determine an accurate bone and soft tissue phenotype for the non-overweight apneic young adult.

Materials and Methods This study was approved by the ethics medical committee of the University hospital of Liege.

This prospective, controlled study will compare cephalometric 3D analysis of bone and craniofacial soft tissue phenotype of young, non-overweight apneic adults using cephalometric 3D analysis between a test group (with AHI 15) and a control group (healthy subjects with AHI < 15).

The inclusion criteria were : (1) patients aged between 18 and 35 years ; (2) Body Mass Index (BMI) lower than 30kg/m² ; (3) alcohol consumption less than 4 unit per day ; (4) tabacco use less than 6 cigarettes per day ; (5) no illicit drug use ; and (6) absence of chronic pathology or medication.

The exclusion criteria were : (1) presence of an acute illness on the day of admission ; (2) patients treated with orthognathic surgery after apnea screening ; (3) patients with polysomnography with a sleep treatment device (PPCN or Mandibular advancement device).

The test group consisted of 23 patients (9 girls and 14 boys) recruited in polysomnography in sleep center of CHU Liege for suspected sleep disorders between 1 january 2022 and 1 april 2023.

Concerning the control group, the participants, healthy adults volunteers are recruited among friends and families of students who collaborate with sleep center for scientific projects. These subjects have no complaints related to OSA and will have to undergo a sleep examination (ventilatory polygraphy) to certify the absence of OSA. This group consisted of 23 patients (14 girls and 9 boys).

This study takes place in two stages. First, all patient are invited to an initial consultation where question about demographics (age, weight, height, gender) and medical history will be asked. At the end of this consultation, only patient of the control group leave with a sleep monitor to record their sleep for one night.

Afterwards, all patients (test and control group) will be invited to undergo a super low dose CBCT in the supine position at CHU Sart Tilman University Hospital.

Demographics and orthodontics data A general history will be taken, including gender, age, height, weight, medical and surgical history (e.g. presence/absence of tonsils and vegetations), current or past regular medication use, presence of allergies associated with allergic rhinitis, presence of asthma and presence of parafunctions.

Cephalometric data An ultra low dose CBCT ( 300μm resolution) will be performed in each patient with a field of 16x18 cm. A computerized 3D analysis will be performed with Dolphin Imaging 11.95 software. All these tools will allow the collection of the following data: parameters concerning the morphological typology and growth potential, the base of the skull, the maxilla, the mandible, the inter-maxillary relationship, the pharynx, the airways as well as the volumes of the different structures.

Sleep data The data will be collected by means of the epworth sleepiness scale (ESS) and a sleep recording of the polysomnography at the hospital type (AASM type 1 sleep recording) for the test group and of the ventilatory polygraph type (AASM type 3 sleep recording) for the control group.

Inclusion Criteria:

• (1) patients aged between 18 and 35 years ;
• (2) Body Mass Index (BMI) lower than 30kg/m² ;
• (3) alcohol consumption less than 4 unit per day ;
• (4) tabacco use less than 6 cigarettes per day ;
• (5) no illicit drug use ; and
• (6) absence of chronic pathology or medication.

Exclusion Criteria:

• (1) presence of an acute illness on the day of admission ;
• (2) patients treated with orthognathic surgery after apnea screening ;
• (3) patients with polysomnography with a sleep treatment device (PPCN or Mandibular advancement device).

Young people (18-35 years) non-overweight apneic divided into 2 groups: a test group (with AHI 15) and a control group (healthy subjects with AHI < 15).