Obstructive sleep apnea is a disorder characterised by repetitive, complete or partial closure of the upper airway during sleep. Many factors, including craniofacial abnormalities, influence upper airway obstruction during sleep. Sleep apnea syndrome (SAS) is related to different combinations of anatomical and functional aspects that produce the airway collapse in individual patients. To compensate for the craniofacial abnormalities and treat sleep apnea, there are some dental and maxillofacial surgical modalities. In this book, treatment and research of SAS are described mainly from clinical and neurophysiological aspects in the stomatognathic system.