Introduction: Attention-deficit/hyperactivity disorder (ADHD) is the most common neurodevelopmental disorder in children and can persist until adulthood. This disorder negatively affects almost all personal, academic, and work fields and often strains parent-child relationships. On the other hand, obstructive sleep apnea (OSA) is characterized by episodes of partial or complete obstruction of the upper airway during sleep. Some studies have suggested an association between OSA and ADHD in children and adults. The Hypothesis: It has been suggested that therapeutic intervention in OSA has a significant improvement in abnormal behaviors such as hyperactivity, inattention, and aggression, and in cognitive and school performance. OSA can lead to ADHD-like symptoms that disappear when OSA is sufficiently treated. The use of oral appliance therapy (OAT) is being studied as a method to control OSA. We hypothesize that the management of OSA with OAT could reduce ADHD symptoms. Evaluation of the Hypothesis: In patients who present with OSA and ADHD simultaneously, it should be evaluated whether the treatment of OSA with the use of OAT as rapid maxillary expansion devices or oral mandibular advancement devices reduces the symptoms of both OSA and ADHD, which would allow the establishment of an alternative method of treatment for both pathologies that is less invasive and less expensive.