Why Does My Mouthguard Fall Out? Loose Mouthguard Fixes

A mouthguard that falls out, slips down or needs clenching to stay in isn't protecting you. Here is why a mouthguard falls out, what you can fix yourself, and when it's time for a remake or a new guard.

The short answer

Most loose mouthguards come down to one of four things: the guard was never shaped to your teeth, the impression or molding wasn't accurate, heat has warped it, or your teeth have changed since it was made. A properly fitted custom guard should stay on your upper teeth without you biting down to hold it.

Why your mouthguard keeps falling out

1. It was never made for your teeth

Stock mouthguards come pre-formed and ready to wear. The ADA notes they often need your mouth closed to hold them in place. Boil-and-bite guards are softened in hot water and bitten into, so they fit more closely, but how well they hold depends on how they were molded at home. A custom guard is formed on a model of your own teeth, which is why it can grip without clenching. For the full comparison, see custom vs. boil-and-bite mouthguards.

2. The impression didn't capture your teeth

A custom guard can only fit as well as the impression it's made from. A shallow bite, a tray that moved while the putty was setting, or putty that wasn't mixed evenly can all leave a model that doesn't match your teeth, and the guard made on it won't grip properly.

3. Heat warped it

Hot water, the dishwasher, a hot car and direct sun can all change a guard's shape. Once the shape changes, so does the fit. Never boil a custom guard to clean it or try to reshape it.

4. Your teeth have changed

Growth, braces, new dental work or a lost tooth can all change how a guard sits. Kids' and teens' teeth are still changing. A guard that fit last season may not fit now.

5. It's worn out

Chewing on a guard, cracks, tears and thin spots all loosen the fit over time. Normal wear is expected, which is why we recommend replacing your mouthguard every year, or sooner if it becomes damaged or worn.

In competition, a guard that falls out costs more than comfort. Under USA Boxing rules, losing it to a punch is a caution, and the third time brings a mandatory warning. More in boxing mouthguard rules.

How to fix a loose mouthguard

• Stop chewing on it. Chewing stretches and thins the edges that hold onto your teeth.
• Check it for warping. If it looks twisted or the edges no longer line up with your teeth, heat may be the cause, and a new guard is the fix.
• Don't re-boil a custom guard. Re-heating it to "re-mold" it can make the fit worse. If you wear a boil-and-bite, follow the instructions in its packaging rather than guessing.
• Don't cut it yourself. Trimming at home can leave rough edges and remove the material that keeps it in place.
• Store it properly. Keep it in a ventilated case, out of hot cars and direct sun. The full routine is in how to clean and care for a custom mouthguard.

Get the impression right the first time

If you're ordering a custom AlienGuard, the impression is where a secure fit starts. These tips come straight from our step-by-step impression guide:

• Read every step first and set a timer for 2 minutes 30 seconds.
• Test the trays. The right tray fits comfortably over all your teeth with a little wiggle room on the sides, and your lips can still close over the front.
• Mix fast. Combine the blue and white putty until the color is even with no streaks, within 15 seconds. S and M trays use one set; L trays use both.
• Bite deep. Center your teeth on the tray and bite down fully until you reach a natural stop. A deep bite is essential.
• Hold still. Don't move your jaw or the tray until the timer ends, then rock the tray gently to remove it.
• Send us a photo. Email a clear photo to support@alienguards.com with your name and order number. We confirm when it's approved before you mail it back.

Messed up the putty or lost a tray? Order a replacement impression kit. Your guard is crafted within 10–14 business days after we receive a good impression.

Wear braces? Don't use the at-home kit. Your dentist takes an impression or 3D scan, then ships it to us or emails it to impressions@alienguards.com, so the braces don't get damaged.

When it's time to replace it

If your guard is cracked, warped, chewed through or no longer stays in without clenching, it's time for a new one. See how often to replace your mouthguard for the signs. If you chose Impression Storage when you built your AlienGuard, we keep your model on file, so you can reorder without a new impression as long as your teeth haven't changed.

If your AlienGuard doesn't fit when it arrives

Email support@alienguards.com with your order number and a short description of the problem. A photo of the guard on your teeth helps. Under our refund and remake policy, we'll review it and make it right, usually with a remake from your impression, or from a new impression if one is needed, at no extra charge. If the remake still doesn't fit or you're still not satisfied, we'll give you your money back for the mouthguard. Normal wear over time isn't a fit problem.

A loose guard can also make you gag, because it keeps moving toward the back of your mouth. If that sounds familiar, read why a mouthguard makes you gag and what helps.

Fitting a whole roster? Team orders get 20% off every model, including NanoBite and PowerBite, with a minimum of 5, and we keep athletes' models on file for quick replacements. See team mouthguard orders.

Loose mouthguard FAQ

Why does my mouthguard keep falling out?

Usually because it wasn't shaped to your teeth, the impression or molding wasn't accurate, heat warped it, or your teeth have changed since it was made.

Should a mouthguard stay in without biting down?

A properly fitted custom guard should. If you have to clench to keep it in, the fit isn't right.

Can I re-boil a custom mouthguard to tighten it?

No. Hot water can warp a custom guard and make the fit worse. Contact us instead, or replace it if it's worn or damaged.

What if my new AlienGuard is loose?

Email support@alienguards.com with your order number and a photo of the guard on your teeth. Our refund and remake policy starts with a free remake.