Snoring mouthpiece not working? Start here

We reviewed 63,184 requests submitted to our returns and exchange portal between 2018 and 2026. The clearest pattern in nine years of customer writing: most mouthpiece problems come down to fit and adjustment, and most of them are fixable without buying anything else.

If you own an adjustable anti-snoring mouthpiece and it is not doing much, the instinct is to conclude the device does not work. Sometimes that is right. More often, reading through nine years of customer explanations, one of four specific things has happened, and three of them are correctable in an evening.

1. The molding was rushed

Boil-and-bite devices take an impression of your teeth. Water slightly too cool leaves a shallow impression that will not grip. Water too hot distorts the tray. Either way the device works loose and comes out overnight.

Here is the number that surprised us most:

Almost everyone treats the first molding as final. It is not. Remolding is repeatable, it costs nothing, and it resolves a large share of the "it will not stay in" complaints we see.

2. The advancement setting was never changed

An adjustable mouthpiece works by holding your lower jaw slightly forward, which opens the airway at the back of your throat. Gradual, stepwise advancement is standard practice in dental sleep medicine, and a 2023 review in European Respiratory Review describes the effect as dose-dependent, meaning the amount of advancement changes the result. The amount of forward movement is the active ingredient. Left at the factory setting, an adjustable device is functionally a fixed one.

The written requests split neatly into two failure modes, and they are opposites:

• Not enough advancement. The device is comfortable, stays in all night, and nothing changes. This is the more common of the two and the easier fix.
• Too much advancement, too fast. The jaw is pushed further forward than it is ready for, and morning jaw stiffness follows. The fix is to back off and rebuild gradually, not to abandon the device.

3. The size is wrong for your mouth

Molding shapes the surface of a tray. It does not change the tray's underlying width or length. A tray that is fundamentally too wide for your dental arch is still too wide after molding, and people discover this on the first night.

Of 4,476 size exchanges in our records, 1,799 stated which direction they were moving:

Among people who pursue an exchange rather than give up, wanting more room outnumbers wanting less by roughly two to one. Both directions are common enough to matter.

Quick self-check. Gagging, lips that will not close, or pressure against the inside of your cheeks usually means the tray is too large. Uncovered back molars, or a device that squeezes the outer edges of your teeth and works loose, usually means it is too small. Our full sizing guide covers how to check before you buy.

4. The cause of your snoring is somewhere else

This is the honest one, and the most common theme in the writing overall: people whose snoring did not reduce as much as they hoped.

Mandibular advancement addresses one specific cause, a lower jaw and tongue that fall back and narrow the airway during sleep. It is a common cause. It is not the only one. An oral appliance cannot reach nasal obstruction, allergies or congestion, alcohol close to bedtime, or airway narrowing related to weight. Our guide to why people snore covers how to work out which cause applies to you. If your snoring originates above the soft palate rather than behind the tongue, a device working on your jaw was never going to be the answer.

Two things worth doing before deciding the device failed:

• Check whether you can breathe through your nose lying down. If you cannot, an oral appliance is working against a blockage further up and will underperform regardless of setting.
• Take loud snoring with daytime exhaustion seriously. Morning headaches, waking unrefreshed, or a partner who has noticed pauses in your breathing warrant a medical evaluation. That is a conversation with a doctor, not a product decision. The American Academy of Dental Sleep Medicine maintains a directory of dentists who assess and fit appliances clinically.

Still stuck?

If you have remolded, worked through the advancement range, and confirmed the size is right, the next step is not another device. Take our snoring solution quiz to check whether a jaw-based approach fits your situation, look through the full range of causes and solutions, or contact our support team and we will work through the fit with you directly.

What this data can and cannot tell you

• These are not rates across all buyers. Every percentage describes people who contacted our support team. Customers who had no trouble had no reason to write, so they are absent by design.
• It reflects one product line. A differently shaped appliance, a tongue-retaining device, or a dentist-made appliance would produce a different picture.
• Self-reported causes are imprecise. We counted the words people used, not a clinical assessment.
• Classification is approximate. Free text resists tidy categories, so unusual phrasing will be missed.