# Oral Appliances for Severe Positional Obstructive Sleep Apnea Syndrome: A Case Report
###### Abstract  
Severe positional obstructive sleep apnea syndrome (POSAS) is a common clinical respiratory disorder with an incidence of 26.7% to 74.5%. Continuous positive airway pressure (CPAP) combined with positional therapy is the gold standard of treatment. However, a mandibular advancement device (MAD) is an effective alternative to CPAP when compliance with CPAP is low or if CPAP is rejected by the patient. A 63-year-old Caucasian male (BMI 26.1 kg/m\({}^{2}\)) complaining of repeated episodes of daytime sleepiness and heavy snoring was diagnosed with POSAS and treated with a MAD. After two years, polysomnographic (PSG) control analysis showed a significant reduction in the number of obstructive sleep apnea/hypopnea episodes per hour (AHI) by 58.9% in the lateral position and 75.5% in the supine position, complete remission of symptoms, a significant reduction in the severity of POSAS, and an overall improvement in quality of life. No adverse events or reduction in compliance were observed during the follow-up period. For severe POSAS, MADs may be an alternative method that is well tolerated by patients and has a good safety profile.  
obstructive sleep apnea syndrome; oral appliances; mandibular advancement device; continuous positive airway pressure; severe OSAS; snoring +
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therapies consist of sleep position trainers worn during sleep that are designed to detect the patient's position using an accelerometer; if a supine position is detected, the system vibrates to prompt the patient to turn to a non-supine position [7]. While positioning therapy alone may not have a positive impact on outcomes, CPAP has several disadvantages. Approximately 5-15% of patients cannot tolerate CPAP due to discomfort, claustrophobia, perception of low benefit, and dryness of the nose or mouth [12]. Additionally, CPAP compliance (defined as CPAP use of more than 4 h per night and more than 70% of nights) varies from 40% to 85% due to excessive daytime symptoms such as sleepiness and neurocognitive changes [11, 13, 14], psychosocial factors, and comorbidities such as insomnia, restless leg syndrome, periodic limb sleep, and complex sleep apnea [15].  
The mandibular advancement device (MAD) is an alternative treatment option to CPAP, with good long-term compliance [11, 16]. It provides a 50% reduction in AHI while reducing snoring, daytime sleepiness, neuropsychological disturbances, and cardiovascular risks similar to CPAP [11]. The main side effects, many of which are transient and associated with mild discomfort [17], when using MADs include temporomandibular joint-related side effects--such as transient morning jaw pain, persistent temporomandibular joint pain, tenderness of masticatory muscles, and joint noises--side effects related to intraoral tissues, occlusal changes, damage to teeth or restorations (tooth mobility and fractures or damage to dental restorations), and appliance problems (appliance breakage, allergies to appliance material, gagging, and anxiety) [18].  
Several meta-analyses and randomized controlled trials have shown that CPAP and MADs demonstrate similar improvements in subjective symptoms such as anxiety and depression [19, 20], quality of life, simulated driving performance [21], common sleep disturbances, and self-reported symptoms [22], with irrelevant differences in cardiovascular changes [23, 24]. The updated 2015 American Academy of Dental Sleep Medicine guidelines suggest that oral appliances may be considered an appropriate adjunct for the treatment of severe OSA [16], but the role of MADs in reducing the severity of positional OSAS remains unclear. The efficacy of MADs is lower than CPAP, but oral appliances have a similar efficacy, with a self-reported compliance rate of about 80%, and are usually preferred over CPAP [25]. Therefore, the aim of this case report was to describe the beneficial effects of a mandibular advancement device in a patient with severe positional OSAS (POSAS).