How to Clean a Night Guard or Mouthguard (Without Ruining It)
Nobody warns you about this bit.
You get a night guard to stop grinding your teeth to bits, you wear it religiously, and somewhere around week three you notice it has developed a smell. Or a film. Or a chalky ridge along the bite surface that was definitely not there when you got it.
A night guard is in your mouth for eight hours a night, every night, often for years. That is more contact time than a retainer, more than a filling, more than almost anything else you own. And most people are cleaning it with a rinse under the tap and a hopeful expression.
Here is what it actually needs, and the handful of things that will wreck it.
The 60-second version
- Rinse it the moment it comes out — cool water, never hot.
- Brush it gently with a soft brush and water. No toothpaste.
- Soak it 15–30 minutes in a cleaning tablet rated for night guards, then rinse.
- Dry it before it goes in the case, and leave the case open during the day.
Why night guards get grubby faster than you'd expect
If you have also worn a retainer, you may have noticed the night guard goes downhill quicker. There are a few reasons for that, and they are all to do with what a night guard is and how it is used.
It is thicker, with far more surface area. A retainer is a thin shell. A night guard has to absorb clenching force, so it is chunky, with a broad biting surface and deep walls. More surface means more places for buildup to settle.
You are grinding on it. That is the entire point of the thing — it takes the wear so your teeth do not. But grinding roughens the biting surface over time, and rougher surfaces hold onto deposit in a way smooth ones do not. This is why the chalky ridge always shows up along the bite line first.
Softer guards are more absorbent. Soft and dual-laminate guards are more comfortable for heavy grinders, but the material is more porous than hard acrylic. It picks up odour more readily and holds onto it.
Your mouth is drier at night. Saliva is your mouth's rinse cycle and it slows right down while you sleep. Eight hours of a covered plastic surface with very little saliva moving across it is when most buildup happens.
People keep them for years. Retainers get replaced. Night guards tend to be kept until they physically fail, which means small cleaning habits compound over a very long time.
The daily routine
This takes under a minute and it is the whole job. Everything else on this page is either a variation on it or a warning about what happens when you skip it.
- Rinse it as soon as you take it out. Cool water. This is the highest-value habit on the list and the one everyone skips — wet deposit rinses away, dried deposit does not.
- Brush gently with a soft brush. Water only, or a drop of clear unscented soap. Pay attention to the biting surface and the inside walls, because that is where buildup gathers.
- Soak it. One tablet, warm water, 15 to 30 minutes. Make sure the guard is fully submerged — anything poking above the waterline does not get cleaned.
- Rinse properly. A good 15 seconds under the tap. You do not want cleaning solution going back in your mouth.
- Dry it, and dry the case. A damp guard in a closed box is a humid little room, and that is where the musty smell comes from.
The bit most people get wrong
Rinsing is not cleaning. A rinse takes off the loose top layer and leaves the film underneath, and it is that film which hardens into the chalky ridge. Rinsing is a genuinely useful habit — it just is not a substitute for the soak.
One tablet a night. 120 tablets — a four-month supply.
Shop tabletsThe weekly deep clean
Once a week, give it longer. A 30-minute soak rather than 15, and take the case with it.
The case is the part nobody thinks about. You can clean a night guard perfectly and undo all of it by putting it straight into a box that has not been washed since you got it. Warm soapy water, a brush, then leave it open to air-dry properly.
If a chalky ridge has already built up, do not attack it. Hardened deposit does not respond to force — it responds to being dissolved, and scrubbing hard just scratches the guard, which makes the next lot build up faster. Soak it a few nights running instead and it will lift in layers.
What never to do to a night guard
Most ruined night guards were ruined by someone trying to clean them properly. These are the ones that do real damage.
| Don't | What happens |
|---|---|
| Hot or boiling water | The guard softens and distorts. A night guard that no longer fits properly does not protect your teeth, and can change how your jaw sits |
| Toothpaste | It is abrasive by design — it has to lift stain off enamel. On guard material it leaves fine scratches that trap more buildup |
| Neat bleach | Degrades the material, leaves a taste that lingers for days, and can turn it a permanent dull white |
| Coloured mouthwash | Stains it, and the alcohol in some brands can craze softer guard materials into fine cracks |
| The dishwasher | Heat again. It will come out a different shape than it went in |
| Leaving it in direct sun to dry | People do this on a windowsill to air it out. Same problem — heat warps it |
| Putting it away wet with buildup on it | Deposit dries hard and bonds to the surface, and the damp closed case does the rest |
Sports mouthguards have their own problem
If yours is for rugby, boxing, hockey or martial arts rather than grinding, most of the above still applies — but the failure mode is different.
A sports guard is worn while you are breathing hard through your mouth, sweating, and probably not thinking about oral hygiene. Then it goes back into a kit bag, damp, in the dark, often still in the bag on Tuesday.
Three things make a disproportionate difference:
- Rinse it before it goes in the bag, not when you get home. The gap between the final whistle and your kitchen tap is where most of the damage happens.
- Never leave it in the car. A car in summer gets hot enough to distort a mouthguard, and a warped guard is worse than no guard because it gives you false confidence.
- Soak it after every session, not weekly. A sports guard picks up more in ninety minutes than a night guard does overnight.
Boil-and-bite guards deserve a specific warning: the material is softer and more porous than a dentist-made one, so it takes on smell faster and holds it longer. If yours has gone permanently funky, that is usually the material rather than your cleaning.
Clean guard, every morning
Dentasheen tablets are rated for night guards, mouth guards, retainers and dentures, and registered as a UK medical device. 120 tablets — four months.
Shop Dentasheen tabletsWhen to replace it
Night guards are consumable. You are deliberately grinding on a piece of plastic so your teeth survive, and eventually the plastic loses.
Signs yours is done:
- Thin patches or holes where you grind hardest — usually over the molars. Once you can see light through it, it has stopped doing its job there
- Cracks or splits, however small
- It has gone permanently cloudy and rough even after a proper soak
- The smell comes straight back within a day of cleaning it
- It has stopped fitting — loose, rocking, or suddenly tight
- Any green or black spotting. Do not try to rescue this one
How long that takes varies enormously with how hard you grind. Heavy grinders can go through one in under a year; light grinders get several. Your dentist will usually spot wear at a check-up before you do, so it is worth mentioning that you wear one.
Anything to do with fit, or any jaw pain, soreness or gum irritation where it sits, is a conversation with your dentist rather than a cleaning problem.
Questions people ask
Why does my night guard smell even though I rinse it?
Because rinsing only removes the loose surface layer. The film underneath is what produces the smell, and it needs either brushing or dissolving to shift. A rinse plus a daily soak sorts it; a rinse alone will not.
Can I use denture tablets on a night guard?
Check the pack actually lists night guards or mouth guards, not just dentures. Guard material and denture acrylic behave differently, and a product only tested on one is a gamble on the other.
Should I keep it in water during the day?
No — dry and ventilated is better. Store it clean and dry in a case with airflow, and leave the case open while the guard is out. Sitting in stagnant water all day is the opposite of what you want.
My night guard has gone yellow. Is it ruined?
Usually not. Yellowing is normally staining from food, drink and time sitting on the surface, and a few nights of soaking makes a real difference. If it stays yellow and feels rough after that, the material itself has changed and it is replacement territory.
How often should I soak it?
Daily. Buildup hardens within days, so a weekly clean is always playing catch-up. Daily soaking is also much less effort overall, because you never have to tackle anything that has set hard.
Is it the same routine for a retainer?
Almost identical, and the same tablets cover both. Retainers are thinner and a bit more forgiving. If you wear both, we have a full guide to why retainers smell and how to fix it, and one on what to do about a cloudy retainer.
In short
A night guard works hard. It takes eight hours of clenching a night so your teeth do not have to, and it deserves better than a rinse under the tap.
Rinse it the second it comes out, brush it gently, soak it daily, dry it before it goes away, and keep the case as clean as the guard. Keep hot water, toothpaste and bleach away from it entirely. That is genuinely the whole routine, and it is the difference between a guard that lasts years and one that goes cloudy and smelly in a month.
One tablet a night
Rated for night guards, mouth guards, retainers and dentures. 120 tablets — a four-month supply.
Shop Dentasheen tabletsKeep reading
- Why your retainer smells — and how to fix it
- Why is my retainer cloudy, yellow or crusty?
- How to choose cleaning tablets
- How Dentasheen works
General information only, not dental advice. If your night guard no longer fits, or you have jaw pain, gum soreness or irritation where it sits, speak to your dentist.