The CPAP vs oral appliance debate has been running for years, and it hasn’t been resolved — nor is it likely to be. The two treatments work differently, suit different patients, and produce different patterns of benefit. What’s changed recently is that we have better data to inform the conversation.

Here’s where the evidence stands heading into mid-2026.

CPAP Remains the Gold Standard for Severe OSA

This hasn’t changed, and I don’t expect it to. For patients with severe obstructive sleep apnoea — an AHI above 30 — CPAP consistently delivers greater reductions in respiratory events than oral appliances. The physics are straightforward: positive airway pressure splints the entire upper airway open, while a mandibular advancement device repositions the jaw to enlarge the retrolingual and retropalatal spaces.

For severe obstruction involving multiple airway levels, mechanical splinting simply achieves more than jaw repositioning in most patients. The latest AASM guidelines (updated late 2025) maintain CPAP as first-line therapy for severe OSA, and the evidence supports that position.

The Story Is More Nuanced for Mild to Moderate OSA

This is where it gets interesting. Several recent randomised controlled trials comparing oral appliances with CPAP in mild to moderate OSA have found that health outcomes — blood pressure reduction, cardiovascular risk markers, daytime sleepiness scores, and quality of life measures — are similar between the two groups.

How? CPAP is more efficacious (it reduces AHI more on the nights it’s used), but oral appliances tend to have higher adherence. Patients wear them more consistently because they’re less intrusive. When you multiply efficacy by adherence to get real-world effectiveness, the numbers converge.

A 2025 meta-analysis published in Thorax analysing seven trials with a combined 1,400 participants found no statistically significant difference in mean arterial blood pressure reduction between CPAP and oral appliance therapy in mild to moderate OSA. That’s a finding with genuine clinical weight.

Adherence Is the Variable That Matters Most

Both treatments only work when patients actually use them. And here, the data is uncomfortable for CPAP advocates. Long-term CPAP adherence — defined as four or more hours per night on at least 70% of nights — hovers around 50-60% in most real-world datasets. Some studies report lower figures.

Oral appliance adherence is harder to measure precisely because the devices haven’t historically had usage monitors. Newer devices with embedded micro-sensors show nightly usage rates of 75-85% in most studies. Patients tell researchers they wear their appliance every night, and the objective data largely confirms it.

This adherence difference matters enormously. A treatment that works 90% of the time but is used half the time delivers less cumulative benefit than a treatment that works 70% of the time and is used every night.

Combination and Sequential Therapy

A growing body of literature supports combination approaches. Some patients use CPAP most nights but switch to an oral appliance for travel or camping — situations where CPAP is impractical. Others start with CPAP, find they can’t tolerate it, and transition to an oral appliance as second-line therapy.

The latest Australian consensus statement recognises this flexibility explicitly, recommending that treatment plans account for patient preference and lifestyle factors alongside disease severity. That’s a practical acknowledgement that the “best” treatment is the one the patient will actually use consistently.

Who Benefits Most From Oral Appliances

Beyond severity grading, certain patient characteristics predict better response to oral appliance therapy:

• Supine-predominant OSA: Patients whose obstruction occurs mainly when sleeping on their back tend to respond well because mandibular advancement is particularly effective for positional airway collapse.
• Lower BMI: Patients who aren’t significantly overweight generally respond better. Excess soft tissue loading in the airway reduces the mechanical advantage of jaw repositioning.
• Younger patients: Jaw joint flexibility and muscle tone contribute to device effectiveness, both of which decline with age.
• Smaller tonsils: Patients with significant tonsillar hypertrophy may not respond as well because the obstruction isn’t primarily at the tongue base.

Phenotyping — determining the specific anatomical and physiological characteristics driving each patient’s obstruction — is increasingly recognised as important for treatment selection. One size doesn’t fit all, and choosing between CPAP and an oral appliance based solely on AHI misses important information.

The Cost Equation

In Australia, CPAP machines cost $1,500-$3,000 upfront, plus ongoing mask and filter replacements of several hundred dollars per year. Some private health insurers partially cover these costs; Medicare rebates are limited.

Custom-fitted mandibular advancement devices cost $1,500-$2,500 through a qualified dental sleep medicine practitioner. They typically last 3-5 years before needing replacement. Over-the-counter “boil and bite” devices are cheaper but generally less effective and less comfortable.

When you calculate total cost of ownership over five years, the two treatments are roughly comparable. Neither has a clear cost advantage.

The Practical Takeaway

Patients asking “which is better?” deserve an honest answer: it depends on your specific situation. Severe sleep apnoea usually needs CPAP. Mild to moderate cases have a genuine choice, and the evidence increasingly supports oral appliances as a legitimate primary treatment for the right patient profile.

The most important thing is that whatever treatment is chosen, adherence is monitored and managed actively. An unused CPAP collecting dust on a bedside table isn’t treating anyone, no matter what the clinical trial data says about its efficacy.