Introduction: Obstructive sleep apnea syndrome is a significant illness affecting a large number of people. It is distinguished by disrupting normal sleep architecture by total or partial restriction of respiratory airflow. Airflow restriction causes a drop in blood oxygen saturation known as hypoxemia, which causes daytime somnolence. Individuals with excessive daytime somnolence have significantly lower productivity, decreased cognition, higher accident rates, and a variety of medical-dental diseases that affect all aspects of their lives. It is well recognized that OSA is related with and can exacerbate a variety of medical conditions, including systemic hypertension, pulmonary hypertension, cardiac arrhythmia, ischemic heart disease, and stroke. This condition can be treated using a variety of conservative and surgical approaches. Weight loss, sleep posture adjustments, intraoral device insertion, nasal continuous positive airway pressure (CPAP), and pharmacological therapy are all examples of conservative treatments. Surgical procedures include tracheostomy, uvulopalatopharyngoplasty, nasal septoplasty, and surgical mandibular advancement. Oral appliances for the treatment of snoring and OSA are divided into two types: those that hold the tongue forward and those that shift the jaw (and attached tongue) forward during sleep. Since the beginning of this century, oral appliances have been regarded as therapy alternatives for upper airway congestion caused by mandibular insufficiency. As it became clear that many devices were somewhat helpful in treating OSA, the producers of these devices sought FDA approval to commercialize these appliances for both OSA and snoring. This chapter discusses obstructive sleep apnea, its pathogenesis, pathophysiology, clinical features, etiology, symptoms, and numerous treatment options, including prosthetic management, as well as the efficacy and complications of oral appliances.