OSAHS (Obstructive Sleep Apnea Hypopnea Syndrome) in children is a frequent respiratory disorder, whose prevalence is estimated at between 1.2 and 5.7%, and which, if left untreated, can cause severe medical complications. This prevalence tends to be underestimated. Diagnosis is made following a clinical examination noting the presence of characteristic clinical and polysomnographic criteria. Multidisciplinary management has been widely described in the literature, and various therapeutic options have been indicated. Rapid maxillary expansion has proved highly effective in the treatment of this condition. This syndrome is a real public health problem and must be diagnosed as early as possible. Through our research, we would like to study whether there is a causal link between an orthodontic problem of the transverse direction and the presence of SAHOS in children. In other words, we would like to assess whether children who clinically present an orthodontic deficiency of their transverse dimension are more likely to develop SAHOS than children without this deficit. If this proves to be true, then a new clinical sign could enable certain healthcare professionals to detect this syndrome early, and be able to refer patients to physicians as soon as possible.

Inclusion Criteria:

• Patient aged between 6 and 16 years
• Patients with a transverse orthodontic deficiency (group "CAS")
• Patients with another type of orthodontic deficiency (group "CONTROL") such as tooth rotation, crowding, mild Angle Class II or Class III dental occlusion
• Patient who has given free, informed oral consent
• Patient whose legal representatives have given their free written consent
• Patient affiliated with a health insurance scheme

Exclusion Criteria:

• Patients refusing to participate in the study
• Patients whose legal representatives refuse to participate in the study