Obstructive Sleep Apnea (OSA) is a disorder characterized by repetitive episodes of partial or complete upper airway obstruction during sleep, which reduces or stops airflow despite continued breathing effort. This blockage causes drops in blood oxygen levels and fragmented sleep, leading to daytime fatigue and other health risks. Oral Appliances (OAs) are custom-made mouthguards offered by sleep specialists and dentists as a non-surgical treatment option. They are an alternative to the continuous positive airway pressure (CPAP) machine, providing a simpler, more portable way to address the physical cause of the obstruction.
The Mechanics of Airway Stabilization
Oral appliances work by altering jaw and tongue position to prevent the soft tissues of the throat from collapsing during sleep. The most common type is the Mandibular Advancement Device (MAD), which fits over the upper and lower teeth. This device gently repositions the lower jaw (mandible) forward and slightly downward. Moving the mandible forward pulls the attached soft palate and the base of the tongue away from the back of the throat. This action increases the size and rigidity of the upper airway, reducing the likelihood of collapse and stabilizing the airway.
A less common type is the Tongue Retaining Device (TRD), which uses suction to hold the tongue forward. The TRD prevents the tongue from falling back into the airway, achieving a similar mechanical result to the MAD.
Determining Treatment Suitability
Oral appliances are a first-line treatment for patients diagnosed with mild to moderate OSA. They are also a standard option for individuals with OSA of any severity who cannot tolerate or refuse CPAP therapy. The decision to use an OA is based on a patient’s anatomy, severity, and preferences.
A custom fit is important for effectiveness and comfort, requiring fabrication by a qualified dentist or orthodontist. Certain conditions contraindicate OA use. These include significant dental problems (like severe periodontal disease or insufficient healthy teeth to anchor the device) or severe temporomandibular joint (TMJ) dysfunction, as the device alters jaw position.
Patients with severe OSA are directed toward CPAP therapy first due to its superior efficacy. OAs are not effective for Central Sleep Apnea, which involves a signaling problem in the brain, not a physical obstruction. Clinicians use sleep study data to determine the initial jaw position, which is later fine-tuned through titration.
Measuring Clinical Outcomes
The effectiveness of an oral appliance is measured by its ability to reduce the Apnea-Hypopnea Index (AHI), the number of breathing cessation or reduction events per hour of sleep. OAs can significantly lower the AHI, but efficacy varies widely. Success is defined as reducing the AHI to below five events per hour, which is considered OSA resolution.
In patients with mild to moderate OSA, oral appliances achieve treatment success in approximately 50% to 70% of cases. On average, OAs reduce the AHI by about 50% across different severities. Some patients experience only a partial response, meaning their AHI is lowered but remains above the acceptable range.
Factors such as a high body mass index (BMI) or more severe sleep apnea limit the success of OA therapy. Mandibular advancement is dose-dependent; greater forward movement of the jaw results in better outcomes, balanced against potential side effects. OAs rarely achieve the same AHI reduction as CPAP, but they lead to similar improvements in daytime sleepiness and quality of life.
Oral Appliances vs. CPAP Therapy
Continuous Positive Airway Pressure (CPAP) remains the gold standard treatment, particularly for severe OSA, as it provides consistent airway support and achieves a greater reduction in AHI. However, effectiveness depends entirely on patient usage. Many people find CPAP challenging to use consistently due to the mask, noise, and bulkiness of the equipment.
Oral appliances have a distinct advantage in patient adherence, meaning people are more likely to use them every night. OAs are smaller, more portable, silent, comfortable, and convenient. Studies show that patients using OAs have higher rates of nightly usage compared to those prescribed CPAP.
Clinical guidelines reflect the trade-off between efficacy and adherence. CPAP is the standard for severe OSA, while OAs are a primary option for mild to moderate cases. The American Academy of Sleep Medicine recommends OAs for patients intolerant of CPAP or who prefer an alternative treatment, recognizing that the best therapy is the one the patient will use.