Treatment of Obstructive Sleep Apnea: Current Strategies to Maximize Oral Appliance Therapy

OAs appear to work by anatomically increasing the size of the upper airway (UA). Advancing the mandible is required for effectiveness² and predominantly increases the airway in a lateral direction behind the palate, and less so behind the tongue.

The US Food and Drug Administration (FDA) now has a list of more than 100 different OAs, all of which work on similar principles of mandibular advancement and they also increase the interincisal distance (simply called “vertical”). While published data on various appliances show total control of OSA in 34% to 55% of patients, there is ongoing research on how far the mandible must be moved forward. Older studies often determined that reduction in the number of breathing events improved the further forward the mandible was moved,³ however these studies had an initial advancement of 75% to 80% of the patient's overall range. Because the average patient has a 10-mm range of protrusive movement, authors believed that a protrusive range of less than 6 mm was a contraindication for OAT. Updated research, in which the initial setting of the OA is minimal, shows that many patients need mandibular advancement of only 2 mm to 5 mm for a drop in apnea-hypopnea index (AHI) of 60%.⁴ Older studies frequently used appliances that had a significant vertical opening (>10 mm), which may relate to the need to advance the mandible to 100% of protrusive range. Opening the interincisal distance to 10 mm was shown to negatively impact the improvement in UA size⁵ but not necessarily the number of breathing events.⁶ Due to high inter-individual variability in response to mandibular advancement, the severity of OSA may actually increase with continued mandibular advancement.⁷

In light of these findings, dentists are starting to assess the overall design of devices with an eye toward limiting vertical opening as well as initial mandibular advancement, while titrating the device based on the individual patient's dental anatomy and response to treatment.

Dentists and physicians are increasingly making observational and clinical efforts to determine predictors of patient treatment success before fabricating an OA. For example, use of anatomical correlates such as retrognathia, a long soft palate, or a steep mandibular plane angle has not been found to predict success or failure. Mechanized advancement of the mandible during overnight sleep recording (ie, polysomnography) has shown good correlation with treatment success, but it is not very accurate at determining which patients will not be successful with OAT or identifying the appropriate effective mandibular position.⁸

The most common medical approach to chronic disease, and one that has seen an increase in use, is combination therapy in patients who have a subtherapeutic response to monotherapy. Cancer is often treated with a combination of chemotherapy, radiation, and surgery; diabetic control may require insulin as well as oral hyperglycemic medications; hypertension may require multiple medications. It is becoming more apparent to sleep medicine practitioners that for many patients the overall control of OSA may require combination therapy.

Weight loss can lessen the severity of OSA, but it does not “cure” it.⁹ Positive airway pressure (PAP) can control OSA in more than 90% of patients, but adherence to therapy has remained consistently poor for decades.¹⁰ OA monotherapy is ineffective in patients with epiglottic collapse. These factors have led to the use of OAs in combination with other standard therapies to improve adherence and medical outcomes.

Patients who are adherent to PAP but unable to tolerate the high pressures necessary to fully correct their sleep-disordered breathing events can combine OAT with their PAP¹¹; this allows for a significant decrease in therapeutic pressures. Patients with positional OSA often have epiglottic collapse, which is incompletely controlled with an OA. Providing positional therapy, which helps the patient avoid the supine position, in combination with OAT may be needed to control the OSA.^12,13Alerting agents may be required in patients who remain clinically sleepy regardless of control of their OSA,^14,15 and nasal steroids may be necessary for those with high nasal resistance.¹⁶

Providers who treat patients with OSA must be cognizant of the multiple options of therapy available, verify the level of effectiveness of any monotherapy, and be willing to guide the patient toward combination therapy as necessary. Because combination therapy requires effective communication and collaboration between dentists and medical providers, being part of a medical team is critical.

For decades, OAT has been discussed in terms of a “lifetime” therapy. Data has shown that up to 50% of patients abandon therapy (both OAT and PAP) within the first year. This is predominantly because they do not feel the treatment is effective in addressing their symptoms of excessive daytime sleepiness or continued snoring,^17,18 while others discontinue therapy because they find the OAs “bothersome to use,” which may underscore patients' lack of understanding as to how serious OSA can be. Attali noted that OAs became less effective with time, which may be related to the natural progression of OSA or wear and loosening of the OA.¹⁸

Of utmost concern is data from 2015 that showed patients who continued to use an OA for more than 10 years, while pleased with the continued control of symptoms, actually had exacerbation of their OSA when wearing their OA.¹⁹ Thus, it seems as if OAT requires ongoing patient follow-up to evaluate efficacy and determine if changes, such as device adjustments, combination therapy, or a different therapy, are needed.

All of these developments in the field of dental sleep medicine reinforce the need for dentists who provide OAT for treatment of OSA to remain aware of new and emerging data that will help improve patient adherence to therapy, understand that OA design changes may improve outcomes, and know that continued follow-up is needed for all patients who receive an OA.