If you’ve been diagnosed with obstructive sleep apnea, there’s a good chance CPAP was the first treatment you were offered. And for good reason — continuous positive airway pressure remains the most effective therapy for moderate to severe OSA. But effectiveness in a clinical trial doesn’t always translate to effectiveness in real life. CPAP adherence rates hover around 50%, and for every patient who adapts to it beautifully, there’s another who can’t tolerate the mask, the noise, or the sensation of pressurized air.

That’s where oral appliance therapy (OAT) comes in.

How Mandibular Advancement Devices Work

The most common type of oral appliance used for sleep apnea is the mandibular advancement device (MAD). It looks like a custom-fitted mouthguard — one piece for the upper teeth, one for the lower — connected by a mechanism that holds the lower jaw forward during sleep.

By advancing the mandible a few millimeters, the device increases the space behind the tongue and soft palate, reducing the likelihood of airway collapse. It’s a mechanical solution to a mechanical problem, and the concept is elegantly simple.

Custom devices are fabricated by dentists trained in dental sleep medicine, typically using digital impressions or traditional molds. The process usually involves two to three appointments: one for impressions, one for fitting, and one for a follow-up titration where the degree of advancement is fine-tuned.

Who’s a Good Candidate?

The American Academy of Sleep Medicine’s clinical guidelines recommend oral appliances as a first-line treatment for mild to moderate OSA, and as a second-line option for severe OSA in patients who can’t tolerate CPAP.

In practice, the best candidates tend to be:

• Patients with mild to moderate OSA (AHI between 5 and 30)
• Patients who’ve tried CPAP and genuinely can’t stick with it
• Patients with positional OSA (worse when sleeping on their back)
• Patients without severe obesity
• Patients with good dental health and sufficient teeth to anchor the device

There are some relative contraindications too. Severe temporomandibular joint (TMJ) dysfunction, significant dental disease, or very few remaining teeth can make oral appliance therapy impractical. Central sleep apnea doesn’t respond to mandibular advancement, so the diagnosis needs to be purely obstructive.

What the Research Says

Let’s be direct: CPAP reduces the apnea-hypopnea index (AHI) more than oral appliances do. On paper, CPAP wins. But here’s the nuance that matters — treatment effectiveness depends on how many hours you actually use the therapy, not just how well it works when you’re wearing it.

Several studies have found that health outcomes (blood pressure reduction, daytime sleepiness scores, quality of life) are comparable between CPAP and oral appliances, precisely because patients wear the oral appliance for more hours per night. A device that works moderately well for seven hours beats one that works perfectly for three hours.

A meta-analysis in the journal CHEST confirmed this pattern: while CPAP was superior in AHI reduction, oral appliances achieved similar improvements in subjective sleepiness, quality of life, and blood pressure.

Potential Downsides

Oral appliances aren’t perfect. Common side effects include:

• Jaw soreness. This is most noticeable in the first few weeks and usually improves with time and morning jaw exercises.
• Excessive salivation or dry mouth. Some patients drool more; others notice mouth dryness. Both tend to diminish.
• Tooth movement. Long-term use can cause small changes in dental occlusion (how the teeth fit together). Regular dental monitoring is important.
• TMJ discomfort. Some patients develop jaw joint symptoms, though this is less common with modern titratable devices.

The biggest concern for clinicians is that oral appliances don’t work for everyone. Roughly 60-70% of patients achieve a meaningful reduction in AHI, but 30-40% don’t respond adequately. There’s no reliable way to predict who’ll respond before trying the device, though some research suggests that drug-induced sleep endoscopy (DISE) can help identify good candidates.

Over-the-Counter vs. Custom Devices

You might have seen boil-and-bite anti-snoring mouthpieces sold online for $30. These are not the same as custom mandibular advancement devices prescribed by a trained dentist. The over-the-counter products lack precision, can’t be titrated properly, may cause more dental side effects, and haven’t been validated for treating diagnosed sleep apnea.

If you’re going to try oral appliance therapy, do it right. Work with a dentist who has specific training in dental sleep medicine, and make sure you get a follow-up sleep study to confirm the device is working.

Making the Decision

There’s no single “best” treatment for sleep apnea — there’s the treatment that a patient will actually use consistently. For many people, that’s CPAP. For others, it’s an oral appliance. And for some, it’s a combination approach or even surgery.

The important thing is that you’re treating the condition at all. Untreated moderate-to-severe OSA carries real cardiovascular and cognitive risks. If CPAP didn’t work out for you, oral appliance therapy is a well-supported, evidence-based alternative worth discussing with your sleep specialist.