Apnoea is a breathing disorder marked by the absence of airflow at the nose or mouth. In children, risk factors include adenotonsillar hypertrophy, obesity, neuromuscular disorders and craniofacial anomalies. The most common treatment for obstructive sleep apnoea syndrome (OSAS) in childhood is adenotonsillectomy. This approach is limited by its surgical risks, mostly in children with comorbidities and, in some patients, by recurrence that can be associated with craniofacial problems. Oral appliances and functional orthopaedic appliances have been used for patients who have OSAS and craniofacial anomalies because they change the mandible posture forwards and potentially enlarge the upper airway and increase the upper airspace, improving the respiratory function.